Transcript 05-Power_and_Control..

04 - Power and Control Devices
04 - Power and Control Devices
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The intent of this presentation is to present enough information to provide the reader with a
fundamental knowledge of electrical power and control devices used within Michelin and to
better understand basic system and equipment operations.
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04 - Power and Control Devices
Module 1 – Relays and Contactors
Module 2 – Overload Relays
Module 3 – IEC and NEMA Components
Module 4 – Control Relay Applications
Module 5 – Timers and Contact Blocks
Module 6 – Solenoids
Module 7 – Troubleshooting Power and Control Devices
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Module 1: Relays and Contactors
Module 1
Relays and Contactors
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Module 1: Relays and Contactors
Theory of Operation
Damper
Case
Magnetic
Circuit
Shading
Ring
Coil
Return
Spring
Contacts
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Moving
Support
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Module 1: Relays and Contactors
Theory of Operation
Purpose
Both relays and contactors provide a means of automatic operation of a machine from a remote location.
A contactor belongs to both the control circuit and the power circuit. The contactor coil and
auxiliary contacts such as those required to seal-in or provide electrical interlock are found in the control
circuit. The remaining main contacts are used to switch loads in the power circuit.
A relay is always used in the control circuit. It is used to remember machine events such as the
momentary closure of a limit switch contact. It is also used to overcome contact constraints, such as,
incorrect type or not enough normally open or normally closed contacts available on a particular device.
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Module 1: Relays and Contactors
Theory of Operation
Damper
Operation and Construction
Case or Housing
Contains all the parts and provides the insulation
necessary to isolate individual contacts.
Case
Contacts
Main contacts, usually three and each of them having
Fixed contact
Magnetic
Circuit
Coil
Movable contact
Sometimes an arc blow-out device
Return
Shading
Spring
Ring
Auxiliary contacts, usually on the device or added
Moving
Support
Contacts
and having Fixed contact; Movable contact
Different types: Normally open contact; Normally closed contact
Note: Auxiliary contacts should open and close at the same time as the main contacts and can be used
to control various other circuits.
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Module 1: Relays and Contactors
Theory of Operation
Damper
Return Spring
This spring insures that the moveable core rapidly moves
away for the stationary core when the coil is de-energized.
This rapid opening insures that the contacts, both main
and auxiliary open as quickly as possible.
Electromagnet
The main feature of a contactor that distinguishes it from
a manual starter is the use of an electromagnet.
The electromagnet is ultimately responsible for
switching the state of the contacts. The electromagnet
consists of the following:
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Case
Magnetic
Circuit
Shading
Ring
Coil
Return
Spring
Contacts
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Moving
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Module 1: Relays and Contactors
Theory of Operation
Damper
Coil
The coil produces magnetic flux as the result of current
flow. The impedance of the coil limits the current in
an AC circuit. The coil's impedance is mainly inductive
reactance since the coil usually has a very low internal
resistance.
Note: Only the DC resistance of the coil limits
the current in a DC circuit.
Case
Magnetic
Circuit
Shading
Stationary Core
Ring
The stationary core concentrates magnetic flux. In doing
so, this core's surface, which mates with the moveable
core, is polarized and attracts the moveable core.
This core is constructed of laminated steel to reduce Eddy currents.
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Coil
Return
Spring
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Contacts
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Moving
Support
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Module 1: Relays and Contactors
Theory of Operation
Damper
Movable Core
The moveable core also concentrates magnetic flux.
The moveable core concentrates magnetic flux radiating
from the mating surfaces of the stationary core. As a
result, the mating surfaces of the moveable core are
attracted to the stationary core resulting in the movement
of the moveable core against the stationary core. The
moveable core is attached through a plastic or insulated
assembly to the contacts.
Case
Magnetic
Circuit
Shading
Coil
As the moveable core is pulled against the stationary core,
Ring
the contacts change state. Since the moveable core is
made to move, it is often referred to as the armature.
This core is also constructed of laminated steel to reduce Eddy currents.
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Return
Spring
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Contacts
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Moving
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Module 1: Relays and Contactors
Theory of Operation
There are two inherent problems when an AC voltage is applied to a relay or contactor coil.
The change in magnetic flux with respect to time induces a voltage in the core resulting in undesirable
induced currents called eddy currents.
The core is constructed of laminated steel to reduce these eddy currents. Laminations serve to
increase the electrical resistance of the core. If the resistance of the core is doubled, the current is
halved. Then from Watt's Law, we see that a reduction in current results in a significant reduction in
power since P = I2R. Eddy currents are undesirable because they result in power dissipated by the core
in the form of heat.
Small Eddy Currents
Large Eddy Currents
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Module 1: Relays and Contactors
Theory of Operation
The magnetic flux produced by the coil also goes to zero twice per cycle due to the alternations of the
sine wave. Since there is no magnetic attraction, the two cores try to pull apart during these two instants
in time. Since this pulling apart would cause the relay or contactor to chatter, something must retain the
magnetic attraction during these times. Shading rings are embedded in the surface of the stationary
core. These rings retain magnetic flux as the coil current passes through zero. The amount of magnetic
flux produced by the coil is proportional to the current through the coil. As coil current passes through
zero, it is making its greatest change with respect to time. Since the flux and current are in phase, flux is
also making its greatest change with respect to time. This rapid change in flux causes an induced
voltage and thus current to flow in the shading ring. As the result of current flow in the shading ring, a
small magnetic field is created. The strength of this magnetic field is sufficient to retain the attraction of
the two cores during the instant the main magnetic field passes through zero.
+
Coil Current
Shading Ring Flux
Main Flux
0
0
270
0
0
90
180
360
0
0
-
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Module 1: Relays and Contactors
Theory of Operation
The contactor and relay functions mechanically exactly the same.
The cross-section drawing below shows how the moveable contacts are mechanically connected to the
moveable part of the magnetic circuit. When the moveable part of the magnetic circuit is pulled against
the return spring, the moveable part of the contacts either closes or opens relative to the stationary set of
corresponding contacts.
The illustration shown is a mechanical representation of
the contactor. The moveable and stationary contacts
must be electrically insulated and isolated from each other,
the magnetic circuit and the coil.
There are many different variations of contact
configurations.
Case
Moveable
Contacts
Coil
Return
Spring
Moving
Support
Stationary
Contacts
Magnetic
Circuit
Mechanical Drawing Cross-Section
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Module 1: Relays and Contactors
Theory of Operation
There are more than one symbols for a contactor or a relay. These devices are a combination of many
symbols, such as contacts and coils. Below is an electrical representation for a contactor and a relay.
Both contain a coil that has terminal numbers A1 and A2. The contactor has three main contacts
numbered L1 –T1, L2 – T2, L3 – T3, which are designed to carry heavy loads to motors, heaters, etc.
The darker lines show these main contacts. The contactors auxiliary contacts are shown with smaller
lines and numbered 13 – 14. The relay has all smaller auxiliary type contacts with different numbers.
The numbers will be different for different configurations of contacts. The one shown is two normally
open and two normally closed.
A1
L1
A2
T1
L2
L3
A1
13
14
T2
T3
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21
31
43
14
22
32
44
A2
Electrical Representation for a Contactor
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Electrical Representation for a Relay
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Module 1: Relays and Contactors
Theory of Operation
Coil Specifications and Definitions
Pick-up voltage - The minimum voltage that causes the armature to move
Seal-in voltage - The minimum voltage that will keep the armature against the stationary core.
Drop-out voltage - The voltage at which the armature starts to move away from the stationary core.
Nominal coil voltage - The ideal voltage for which the coil is designed. A relay or contactor will
typically operate properly when the actual voltage applied is 85 to 110% of the nominal voltage.
Example: If the nominal voltage is 120v, then the typical operating range is 102-132 volts.
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Module 1: Relays and Contactors
Theory of Operation
Coil VA rating
The apparent power rating of the coil depends upon armature position and is specified as inrush and
sealed. Inrush condition occurs when the voltage is applied to the coil but the armature has not moved
completely against the stationary core.
The sealed condition occurs when the armature is completely seated against the stationary core. Typical
VA ratings for a standard relay or contactor coil could be 80VA inrush and 7VA sealed. For a coil with a
nominal voltage of 120 volts, this translates to 667 mA inrush current and 58.333 mA seal-in current.
This difference in current from inrush to seal-in is approximately 10-12 times greater.
This large difference in current can be directly related to coil failure. This is due to excessive current in
the coil if the armature does not become sealed properly or in a reasonable amount of time.
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Module 1: Relays and Contactors
Theory of Operation
As the term inrush implies, there is an inrush of current when the coil is initially energized. This inrush of
current is the result of the armature position (unseated). When the armature is not seated, the
impedance of the coil is low resulting in an excessive amount of current (inrush). Since the internal
resistance of the coil is very low, the inductance of the coil is the main determining factor for the
impedance.
The inductance of the coil is directly proportional to the coil core’s permeability. On the next pages we
will discuss how permeability of the core affects the current in the coil.
Permeability is a measure of a material’s ability to concentrate magnetic flux.
Relative Permeability is a measure of a material’s ability to concentrate magnetic flux as
compared to air (air being equal to 1)
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Module 1: Relays and Contactors
Theory of Operation
When the armature is not seated, the relative permeability of the coil's air core is very low (approximately
equal to unity or 1). This results in low inductance, low inductive reactance, and thus low impedance.
The following equation gives the relationship between inductance (L), relative permeability (r) and the
coil size.
2
N A
L = r
l
A coil's inductance depends on how it is wound, the core material on which it is wound, and the number
of turns of wire with which it is wound.
1. Inductance increases greatly as the number of turns of wire around the core increases since it is
squared.
2. Inductance increases as the relative permeability of the core material increases. The relative
permeability of air is approximately 1 and the relative permeability of an iron core is approximately 400500 times greater than that of air.
3. Inductance increases as the area enclosed by each turn increases. Since the area is a function of the
square of the diameter of the coil, inductance increases as the square of the diameter.
4. Inductance decreases as the length of the coil increases (assuming the number of turns remains the
constant).
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Module 1: Relays and Contactors
Theory of Operation
For the relationship below, if the number of turns, area of the core, and the length of the core all remain
constant for a given coil; then the permeability of the coil's core is the determining factor for the
inductance of that coil. For an air core (r = 1), the inductance is very low. For an iron core (r = 500),
the inductance is very high.
L= X L
2 f
where L = inductance, measured in h
f = frequency, measured in Hz
=
X L inductive reactance, measured in 
In this relationship, if the inductance increases, then the inductive reactance increases. If the inductance
decreases, then the inductive reactance decreases. Inductive reactance is the opposition to AC current
due to the inductance in the circuit.
V
I =
XL
In the case of an air core, XL is very low, and the current in the coil is high. In the case of an iron core,
XL is very high, and the current in the coil is low.
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Module 1: Relays and Contactors
Contactor Applications
Direct-On-Line Starting of an AC Motor
This is the simplest method of starting AC motors. The expression "direct-on-line starting" means that
the full electrical supply voltage is connected directly to the motor terminals, usually by means of a
"contactor".
Seal-in Circuit
In order to comply with the requirements of the relevant regulations, a D-O-L starter comprises:
1. Efficient means for starting and stopping the motor.
2. Means to prevent automatic restarting (known as under-voltage protection or “seal-in circuit”) after a
stoppage due to a drop in voltage or complete failure of supply, where unexpected restarting of the motor
might cause injury to an operator.
3. A suitable device providing means of protection against excess current in the motor or in the cables
between the device and the motor. This is known as "over-current protection".
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Module 1: Relays and Contactors
Contactor Applications
DISC
M
L1
L2
L3
1FU
2L1
T1
1L2
2FU
2L2
T2
1L3
3FU
2L3
T3
MTR
4FU
460 V
60 Hz
OL
1L1
5FU
3L2
3L3
H1
H3
H2
H4
T
24 V
X1
X2
NL
6FU
STOP
OL
1
START
1PB
3
2PB
4
5
2
M
M
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Module 1: Relays and Contactors
Contactor Applications
Direct-On-Line Reversing
Motor starters are used when it is desired to reverse the direction of rotation of a three-phase squirrelcage motor. The standard arrangement consists of a set of two, three pole; contactors operated electromagnetically and mechanically linked together. They are usually controlled by three push buttons:
Forward, Reverse, and Emergency Stop. The connections of one contactor reverse the supply voltage
to two of the three motor terminals.
1DISC
L1
1L1
1FU
2L1
L2
1L2
2FU
2L2
L3
1L3
3FU
1MF
1OL
T1
T2
1
MTR
2L3
T3
480 V
60 Hz
TO NEXT PAGE
1MR
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Module 1: Relays and Contactors
Contactor Applications
Electrical and Mechanical Interlocking
Opposing motions shall be electrically interlocked, as well as, mechanically interlocked. The
mechanical interlock will not allow both forward and reverse contactors to be energized at the same time.
If this could happen, 2L1 and 2L3 would be tied to T1 and T3 at the same time causing a short circuit.
The electrical interlock (N.C. 1MF and 1MR) protects the coils for 1MF and 1MR.
STOP
Example: If 3PB were pressed while the
machine is running forward, inrush current
would flow through 1MR coil. Since the
mechanical interlock is stopping the contactor
from closing, the moveable core stays open
which would cause the coil to overheat and
destroy itself.
1OL
1
FORWARD
1PB
3
2PB
4
1MR
5
6
2
1MF
1MF
REVERSE
3PB
1MF
7
8
1MR
1MR
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Module 1: Relays and Contactors
Contactor Applications
Design Techniques for Limit Switches
There are many different techniques for limit switches when applied to a control circuit. The techniques
and physical locations of the limit switches illustrated below are examples of recommendations and not
requirements.
1. One technique is a limit switch used as a control stop device to prevent moving parts of machines
from over-running the normal mechanical limits of the machine. Notice the location of 1LS in the circuit
below. It is located in the right side of the schematic as a control stop device. The machine will stop
when 1LS is actuated and is limited to that amount of travel only. This ensures that moving parts are
brought to rest at the correct position. 1LS is using a normally closed (N.C.) contact for this operation.
Control stop devices stop machines for normal operations.
2PB
1OL
1
1PB
3
1LS
4
5
6
2
1M
1M
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Module 1: Relays and Contactors
Contactor Applications
Design Techniques for Limit Switches
2. The configuration below is an example of the same circuit above except the limit switch is shown in
the held position to represent the home position for the machine. 1LS is using a normally closed
contact but it is held open (N.C.H.O.) to designate the home position.
2PB
1OL
1
1PB
3
1LS
4
5
6
2
1M
1M
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Module 1: Relays and Contactors
Contactor Applications
Design Techniques for Limit Switches
3. Another technique is a limit switch used as
a control start device. To reverse the motion
of the machine at the end of a stroke, 2LS is
ESTOP
FORWARD
1OL
1PB
2PB
2LS
1MR
used as a control start device and is located
1
3
4
5
6
7
2
1MF
in the middle of the schematic. Notice that 3PB is also a control start device 1MF
for the reverse motion and
2PB is for the forward motion. Notice that 1LS
and 2LS are used as control stop devices.
When the forward motion moves the machine
from the 1LS position to the 2LS position, the
REVERSE
3PB
1MF
motor forward contactor will de-energize by 2LS (N.C.) and the forward motion will 8stop.1LSNow
2LS
(N.O.)
9
10
1MR
also closes and will reverse the motion of the
1MR
machine back to the home position (1LS).
2LS
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Module 1: Relays and Contactors
Contactor Applications
Design Techniques for Limit Switches
4. Another technique is a limit switch used as a safety stop device for safety conditions to be met
before the machine can be started.
Example: Limit switches on lift gates or guards protecting operators from moving parts of machinery.
Notice the location of 1LS in this circuit. It is located in the left portion of the schematic as a safety stop
device. Opening the gate or guard will stop the machine. 1LS is using a normally closed (N.O.H.C.)
contact for this operation. 1 LS and 1PB are personnel safety stop devices. 1OL is an equipment
safety stop device.
2PB
1OL
1
1LS
1PB
3
4
5
6
2
1M
1M
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Module 1: Relays and Contactors
Forward-Reverse Contactor with Limit Switches to Control Stopping of the Opposing Motions
FROM LAST PAGE
1L1
1L2
4FU
5FU
3L1
3L2
H1
H3
H2
H4
1T
X1
24 V
X2
6FU
1NL
STOP
1OL
1
FORWARD
1PB
3
2PB
4
1LS
5
1MR
7
6
2
1MF
1MF
REVERSE
3PB
1MF
2LS
8
9
10
1MR
1MR
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Module 1: Relays and Contactors
Automatic Forward-Reverse Contactor with a Limit Switch to Start the Opposing Motion
FROM LAST PAGE
1L1
1L2
4FU
5FU
3L1
3L2
H1
H3
H2
H4
1T
X1
24 V
X2
6FU
1NL
STOP
1OL
1
FORWARD
1PB
3
2PB
4
1LS
5
1MR
7
6
2
1MF
UP
1MR
DOWN
1MF
REVERSE
3PB
1MF
2LS
8
9
10
1MR
1LS
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Module 1: Relays and Contactors
Simple Contactor with 2 Start Pushbuttons
DIS
C
M
1L1
1FU
2L1
L2
1L2
2FU
2L2
L3
1L3
3FU
2L3
L1
OL
T1
T2
MTR
4FU
460 V
60 Hz
T3
5FU
3L
2
3L
3
H1
H3
H2
H4
T
24 V
X1
X2
6FU
NL
OL
1
1PB
3
2PB
4
3PB
5
6
M
2
4PB
M
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Module 1: Relays and Contactors
Simple Contactor with 2 Start Pushbuttons
DIS
C
M
1L1
1FU
2L1
L2
1L2
2FU
2L2
L3
1L3
3FU
2L3
L1
OL
T1
T2
MTR
4FU
460 V
60 Hz
T3
5FU
3L
2
3L
3
H1
H3
H2
H4
T
24 V
X1
X2
6FU
NL
OL
1
1PB
3
2PB
4
3PB
5
6
M
2
4PB
M
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Module 1: Relays and Contactors
This Concludes
Module 1
Relays and Contactors
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Module 2: Overload Relays
Module 2
Overload Relays
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Module 2: Overload Relays
Construction
TELEMECANIQUE
LR1-D
COVER
UPPER DIFFERENTIAL OPERATOR
LOWER DIFFERENTIAL OPERATOR
DIFFERENTIAL LEVER
BI-METAL
CAM
THERMAL COMPENSATION
BI-METAL
ADJUSTING LEVER
TRIPPING SLIDE
MOVING CONTACT
SUPPORT
CASE
RESET BUTTON
RETURN SPRING
CONTACTS
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Module 2: Overload Relays
O/L Specifications
Operating Ranges
LR1-DO9
0.1-0.16A
0.16-0.25A
0.25-0.4A
0.4-0.63A
0.63-1.0A
LR1-D12
LR1-D16
LR1-D25
LR1-D40
LR1-D63
10-13A
13-18A
18-25A
23-32A
30-40A
38-50A
48-57A
57-66A
1-1.6A
1.6-2.5A
2.5-4A
4-6A
5.5-8A
7-10A
Maximum Voltage: 600V AC or DC
Frequency Range: up to 400 Hz
Contacts: 1 Normally Open and 1 Normally Closed
Ambient Temperature Compensation
From
-4
to
-20
to
140 °F
60 °C
Differential: Phase loss and phase unbalance detection
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Module 2: Overload Relays
Adjustment and ResettingFunction
Adjustment - Adjusting dial must be set to read the full load current of the motor (FLC).
Resetting - Resetting is done by pressing the blue reset button after the bi-metal elements have been
allowed to cool down.
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Module 2: Overload Relays
Mechanical Operation.
Thermal Compensation Bi-Metal
Tripping
Slide
Reset Button
Case
Return
Spring
Contacts
Bi-Metals
Differential Operator
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Cam
Moving Contact Support
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Module 2: Overload Relays
Differential Operation
d
Cold Position - The differential operators are hard over to
the right
d
Warm Position - NORMAL BALANCED CURRENT - The 3
bi-metals and the operators move to theleft the same distance d
Warm Position - BALANCED OVER CURRENT - The 3
bi-metals and the operators move over to the left the same
distance which trips the overload relay. Tripping current is 125%
of the actual adjusting dial value
d
Warm Position - UNBALANCED CURRENT - The unbalanced current
causes unequal deflection of the 3 bi-metal strips. The differential lever
amplifies this unequal deflection. The distance d is also amplified and
causes the mechanism to trip. The tripping current for an unbalanced
current is equal to 80% of the current for 3 balanced phases
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Module 2: Overload Relays
Features
LR2D Bimetallic Overload Relays
*
Class 10 Protection - 0.10 to 140 Amps
*
Class 20 Protection - 2.5 to 80 Amps
*
With or Without Phase Loss and Phase
Unbalance Protection
*
Ambient Temperature Compensated
*
High Resistance to Shock and Vibration
*
Proven Reliable Protection
*
Withstand in Excess of 17X Thermal Rating
*
Precise Settings by Graduated Dial
*
Separate Stop and Reset Functions
*
Manual/Auto Reset Selector
*
Setting Dial Cover can be Sealed
*
Trip Indication/Test Button on Front
*
Lockable Cover
*
Remote Reset - Remote Test
*
Direct Mounting to D-Line Contactors or Panel
Mounting with Optional Bracket
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Module 2: Overload Relays
Features
Benefits
B1-Stop function for
instantaneous circuit
isolation
B2-Manual position for local or
automatic position for
B3-Provides visual indication of
trip status
B4-Easily adjustable trip range
B5-Provides visual indication
and protection against
unwanted tampering of
reset and trip settings
B6-Provides flexibility in
installations in control
panels
B7-Overload not affected by
temperature
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Features
F1-Separate Stop and Reset
Function
F2-Reset Button can be
Switched from Manual to
Automatic Position
F3-Trip Test Button with
Indicator
F4-Full Load Current Trip
Setting with Graduated Dial
F5-Clear Cover for Manual/Auto
Reset Selector and Trip
Range Dial can be Sealed
F6-Mounts directly to contactor
or to bracket for panel
mounting
F7-Ambient compensated
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Module 2: Overload Relays
This Concludes
Module 2
Overload Relays
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Module 3: IEC and NEMA Components
Module 3
IEC and NEMA Components
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Module 3: IEC and NEMA Components
IEC and NEMA Components
The Organizations and Goals
IEC - The IEC (International Electro-technical Commission) was conceived as an idea in 1904 during a
meeting of the International Electrical Congress in St. Louis, Missouri. The first meeting of the IEC was
held in London, England, in 1906. Its voting body consists of 42 member nations, each having one vote
on the Commission. The United States is one of the voting members. Presently, the IEC is
headquartered in Geneva, Switzerland. The IEC is international and its activities have traditionally been
associated with equipment used in European common market countries.
The IEC has developed recommendations to which manufacturers may test and publish technical
information that provides potential customers with a basis for product comparison.
"IEC Type" starters, contactors or overload relays refer to devices manufactured and tested per
IEC recommendations.
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Module 3: IEC and NEMA Components
IEC and NEMA Components
NEMA - NEMA (National Electrical Manufacturers' Association) was formed in 1926 and is
headquartered in Washington, D.C. NEMA presently has 550 members, most of who are North
American manufacturers of electrical and electronic products. The activities of NEMA have
predominantly been associated with equipment used in North America.
The primary goal of NEMA is to establish standardization within North American electrical industry.
NEMA has developed product design standards and test specifications for device qualifications, many of
which have been adopted by UL (Underwriters Laboratories). NEMA specifies the ratings a device must
carry in order to be labeled with a NEMA designation. For example, a contactor must show motor
ratings of 10 HP @ 460 volts and 7.5 HP @ 230 volts on its nameplate to be designated "NEMA Size 1."
IEC and NEMA do not perform device testing. The manufacturers of the equipment do testing. IEC
does publish parameters for life testing of contactors -- NEMA does not. The IEC life test does not state
what the overall test results should be. However, they do recommend that the minimum electrical life of
a contactor should be at least 1/20 of its mechanical life.
"NEMA Type" devices refer to those traditionally supplied by the major U.S. manufacturers of
motor controls.
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Module 3: IEC and NEMA Components
IEC and NEMA Components
UL - Underwriters Laboratories was founded in 1896 as a private laboratory. Initially, its work involved
testing equipment for insurance companies. UL directs its attention to verifying that an electrical product
will not cause fire or shock when properly installed. The UL listing mark is significant to market
acceptance of products in the United States.
NEMA, UL or IEC does not dictate levels of electrical or mechanical life. In Europe and North America,
the market dictates the level of device performance.
Confusion can result when two devices showing the same horsepower rating are significantly different in
size. The traditional NEMA type contactor, designed to provide a very high level of performance, is
larger than the equivalently rated IEC type device. Size difference is more evident among contactors
below 50 horsepower (at 460 volts). At 50 horsepower and above, the size difference is less evident
because of the larger arc to be extinguished when the contacts are opened. Emphasis is placed on the
small frame devices because 80% of the contactors and starters used in the world are less than 50 HP.
These devices did not evolve differently because of IEC and NEMA. Market requirements influenced
manufacturer design.
To some degree differing economic conditions in the two parts of the world led to different market
requirements and, as a result, different approaches toward the manufacture of electrical contactors.
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Module 3: IEC and NEMA Components
IEC and NEMA Contactors
IEC Type - In Europe there has historically been relatively short supply and high cost of raw material. In
the interest of conserving materials, designers considered the average application and used no more
material than was required. This resulted in smaller size devices per horsepower rating, and therefore
devices that are more application sensitive. Greater knowledge and care are necessary for proper
application.
NEMA Type - In North America, materials were plentiful and relatively inexpensive. The market
demanded a very high level of performance throughout a wide range of motor applications. As a result,
this eliminated much of the possibility of human error in application because it became extremely simple
to select the appropriate device for a given application. Very rarely did the designer have to know any
more than the horsepower and voltage of the motor to select the proper size device.
Both types of contactors provide advantages. The designer makes the choice based on usage
considerations.
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Module 3: IEC and NEMA Components
IEC and NEMA Contactors
Application
IEC type and NEMA type contactor application information and philosophy differ significantly. IEC type
application information must be understood in order to achieve the desired level of device performance.
IEC Type Contactors
The primary function of the IEC is to recommend contactor test criteria and procedures which
manufacturers may use to test and publish results. Published IEC type technical information is a
statement of IEC recommended test results. A judgement must be made regarding how the laboratory
test results actually relate to specific applications.
One million electrical operations and a mechanical life of 10 million operations are generally
accepted expectations for IEC contactors below 50 horsepower (These expectations are based
on a standard squirrel-cage motor operating under normal conditions). Life expectations are less
for contactors 50 horsepower and above. These levels of performance originated as a European market
requirement for contactors.
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Module 3: IEC and NEMA Components
IEC and NEMA Contactors
NEMA Type Contactors
At the smaller horsepower ratings, electrical life expectations for traditional NEMA type contactors on
tests per the IEC recommendations would be between 2.5 and 4 times greater than equivalently rated
IEC type devices. Expectations vary based on manufacturer. In the middle sizes, the differences in
expectations decrease. In the very large sizes, electrical life expectations of NEMA type and IEC type
devices are about the same.
NEMA type contactors provide a high level of performance for a wide range of applications, including
some jogging duty. Some refer to that as extra or reserve capacity.
Short Circuit With-Stand-Ability
NEMA type contactors and overload relays are designed to withstand the let-through energy of a
short circuit protective device available in the U.S. IEC devices were designed for coordination
with fast acting European style fuses. Care must be taken in their application with slower acting
U.S. fuses to avoid severe damage to circuit components
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Module 3: IEC and NEMA Components
IEC and NEMA Overload Relays
NEMA Type Overload Relay
The most common NEMA type overload relay is a stored energy, eutectic-alloy device (also called solder
pot or melting alloy overload relays) that utilizes a special alloy that melts when damaging overload
currents are present. This allows a ratchet wheel to spin free and release spring-loaded electrical
contacts to de-energize the contactor and disconnect the motor from the line.
The current in each phase of the motor is passed through a separate heater coil to heat an individual
thermal unit containing the eutectic alloy. Because this type of overload relay senses current in each line
independently, it will protect a motor from overload conditions as a result of single phasing or unbalanced
currents. When the current in any one line exceeds the safe operating current for the motor, beyond the
specified time limits, the overload relay will trip.
The typical NEMA type overload relay utilizes interchangeable heater coils. This not only allows the
device to easily and inexpensively be adjusted to protect motors of varying full load current at the same
horsepower rating, but allows the same overload relay to be used with motors of a different horsepower
rating, for different system voltages.
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Module 3: IEC and NEMA Components
IEC and NEMA Overload Relays
IEC Type Overload Relay
IEC type overload relays are bimetallic devices. A bimetal is made up of two strips or more of metal having different
coefficients of expansion, attached together such that when heated, the metals expand at a different rate and cause
the bimetal to bend. Motor current is utilized within the overload relay to heat three separate bi-metals, one per phase.
An overload causes the bi-metals to operate a set of contacts, de-energizing the contactor and disconnecting the
motor from the power lines.
The IEC type overload relay is designed to provide single phase sensitivity. This sensitivity results in overload
protection under single phase conditions. If one of the phases should be lost, one of the bimetal elements is not
heated. The force it contributes toward operating the overload relay is also lost. The IEC type overload relay includes
a mechanical means to compensate for this loss. As two bi-metals push forward, being heated by current, the
differential operators sense this phase loss and cause the relay to trip.
The IEC type overload relay is also designed to provide ambient temperature compensation. The overload relay is
normally located in a different environment than the motor. Because of this, a fourth bi-metal strip is located in the
overload relay to provide for ambient compensation for the temperature of its environment. A properly designed
ambient compensating element reduces the effect on the overload relay caused by ambient change. This allows an
overload relay of this configuration in a varying ambient temperature to properly protect the motor.
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Module 3: IEC and NEMA Components
IEC and NEMA Overload Relays
IEC Type Overload Relay
The IEC type overload relay is also designed to provide mechanical trip adjustment. This adjustment allows a
particular overload relay to be used for a different range of motors. Most new type IEC overload relays are designed
to be adjusted in the field for either manual or automatic reset operation.
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Module 3: IEC and NEMA Components
This Concludes
Module 3
IEC and NEMA Components
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Module 4: Control Relay Applications
Module 4
Control Relay Applications
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Module 4: Control Relay Applications
Control Circuit Grounding Systems
Control Voltages
24 Volt Control Circuit - This voltage is considered as a safe voltage and must be obtained by using
an isolated type transformer (auto transformers are not allowed). It guarantees adequate protection
for personnel and must be used in damp areas.
120 Volt Control Circuit - This voltage is not to be considered as a safe voltage and must be
obtained by using an isolated type transformer (auto transformers are not allowed).
Control System Examples
1. An ungrounded control circuit used with either a 24V or 120V control transformer.
- The secondary side of the transformer is
not grounded
- The control circuit must be protected by
two fuses
H1
H3
H2
X1
6 Fu
H4
T
X2
7Fu
2PB
1OL
1
1PB
3
1LS
4
5
6
2
1M
1M
A
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Module 4: Control Relay Applications
Control Circuit Grounding Systems
Control Voltages
- A ground fault at A, nothing happens.
- A ground fault at A and B, the control devices between wire #1 and 6 are shorted out due to a current
path around them. Therefore, the machine goes out of control. Contactor 1M is energized and neither
the overcurrent relay nor the stop button can de-energize it.
H1
-
A ground fault at A
and C, 6 Fu or 7 Fu,
and possibly both,
will open.
H3
H2
H4
T
X1
X2
6 Fu
1OL
1
7Fu
2PB
1PB
3
1LS
4
5
6
2
1M
A
1M
B
C
This type circuit is not acceptable due to safety hazards.
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Module 4: Control Relay Applications
Control Circuit Grounding Systems
2. A grounded control circuit used with a 120V center tap control transformer.
- The center tap of the transformer is grounded.
- The control circuit must be protected by two fuses.
H1
H3
H2
H4
T
X1
X2
6 Fu
1OL
1
7Fu
2PB
1PB
1LS
3
4
5
6
2
1M
1M
B
A
A ground fault at A, 6 Fu opens because there is a short circuit across the left side of the transformer.
Contactor 1M remains energized if it was energized before the ground fault occurred, since 60 volts is
enough to hold it in.
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Module 4: Control Relay Applications
Control Circuit Grounding Systems
- A ground fault at B, 7 Fu opens because there is a short circuit across the right side of the transformer.
Contactor 1M remains energized if it was energized before the ground fault occurred, since 60 volts is
enough to hold it in. In both cases the ground fault will not be noticed until the machine is stopped and
an attempt to be started again.
H1
H3
H2
H4
T
X1
X2
6 Fu
1OL
1
7Fu
2PB
1PB
1LS
3
4
5
6
2
1M
1M
B
A
This type circuit is not acceptable due to safety hazards.
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Module 4: Control Relay Applications
Control Circuit Grounding Systems
- A ground fault at B, 7 Fu opens because there is a short circuit across the right side of the transformer.
Contactor 1M remains energized if it was energized before the ground fault occurred, since 60 volts is
enough to hold it in. In both cases the ground fault will not be noticed until the machine is stopped and
an attempt to be started again.
H1
H3
H2
H4
T
X1
X2
6 Fu
1OL
1
7Fu
2PB
1PB
1LS
3
4
5
6
2
1M
1M
B
A
This type circuit is not acceptable due to safety hazards.
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Module 4: Control Relay Applications
Control Circuit Grounding Systems
3. A grounded control circuit used with a 120V center tap control transformer and a ground fault relay
(GFR).
- The center tap is grounded through a 60 volt ground fault relay.
- The control circuit must be protected by two fuses.
H1
H3
H2
H4
T
6 Fu
8Fu
7 Fu
2PB
1OL
7
1
X2
GFR
X1
1PB
3
1LS
4
5
6
2
1M
1M
A
B
C
GFR
8
1LT
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Module 4: Control Relay Applications
Control Circuit Grounding Systems
A ground fault at A or B or C, the relay GFR gets energized and indicates the fault (1LT is on). The
machine continues to function. This circuit is to be only used whenever the interruption of the machine
causes product damage. An example would be a production area where the product would be damaged
beyond repair if the cycle was interrupted and the cost would be very large.
H1
H3
H2
H4
T
6 Fu
8Fu
7 Fu
2PB
1OL
7
1
X2
GFR
X1
1PB
3
1LS
4
5
6
2
1M
1M
A
B
C
GFR
8
1LT
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Module 4: Control Relay Applications
Control Circuit Grounding Systems
Note: A ground fault at A or B has to be repaired as soon as possible. If a second ground fault occurs
on the left side of the coil (A or B whichever was first) the machine goes out of control. A ground fault at
C also needs to be repaired as soon as possible because if a second ground fault occurs on the left side
of the coil (A or B) 7 Fu and/or 8 Fu opens, which opens the circuit and interrupts the machine's
operation.
H1
H3
H2
H4
T
8Fu
7 Fu
2PB
1OL
7
1
X2
GFR
X1
6 Fu
1PB
3
1LS
4
5
6
2
1M
1M
A
B
C
GFR
8
1LT
This grounded control circuit is considered to be safe as far as keeping good control of the
machine's operation. But don't overlook that all metallic parts have to be grounded properly in
order to protect personnel against electrical shocks.
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Module 4: Control Relay Applications
Control Circuit Grounding Systems
4. Grounded control circuit used with a 24 volt or 120 volt control transformer.
- X2 terminal of the secondary must be grounded.
- One side of the coil must be connected to this terminal through a neutral link (1NL).
H1
H3
H2
H4
T
X1
X2
6 Fu
1 NL
2PB
1OL
1
1PB
3
1LS
4
5
6
2
1M
1M
B
A
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Module 4: Control Relay Applications
Control Circuit Grounding Systems
- A ground fault at A, 6 Fu opens. No more voltage is applied to the control circuit.
- A ground fault at B, nothing happens. The first ground fault occurring at the left side of the coil 1M will
open the fuse 6 Fu and de-energize the circuit.
H1
General Conclusion
The control system #3 is
adopted for special applications
only. The control system #4 is
the one adopted by most
manufacturers to control
machinery. It has proven to be
the safest for both personnel
and equipment.
H3
H2
H4
T
X1
X2
6 Fu
1 NL
2PB
1OL
1
1PB
3
1LS
4
5
6
2
1M
1M
B
A
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Module 4: Control Relay Applications
Control Circuit Grounding Systems
Control Relay Master Circuit
This circuit is designed to protect the system if any of the safeties in the circuit are activated. When the
safeties are activated the CRM coil is de-energized which disables the rest of the circuit.
The system would then have to be rearmed to
allow the circuit to be restarted.
L1
L2
L3
1DISC
1M
1OL
1L1
1FU
2L1
1L2
2FU
2L2
1T2
1L3
3FU
2L3
1T3
4FU
1T1
MTR
5FU
3L1
3L2
H1
H3
H2
H4
1T
X1
6FU
X2
1NL
7FU
1LT
CRM
3
4
2
G
1OL
1
1PB
5
1PS
6
1LS
7
2LS
8
2PB
9
CRM
10
CRM
M
3PB
CRM
11
12
M
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Module 4: Control Relay Applications
Control Circuit Grounding Systems
Jog Circuits
Using only pushbuttons to create a jog circuit will only work if the contacts change states a certain way.
When the JOG button is pressed, the normally closed contacts have to break before the normally open
ones close. When the JOG button is released the normally open contacts have to break before the
normally closed ones close again. With most pushbuttons this causes a race problem with the contacts
and sometimes the contactor will seal in even when jogging. The only way to insure that the contacts
won’t have a race condition is to use a separate control relay.
4FU
5FU
H1
H3
H2
H4
1T
X1
X2
1NL
6FU
1OL
1
1PB
RUN
1M
3
1M
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JOG
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Module 4: Control Relay Applications
Control Circuit Grounding Systems
Jog Circuits
Using a control relay as below insures that the race condition is eliminated.
4FU
5FU
H1
H3
H2
H4
1T
X1
X2
1NL
6FU
1OL
1
1PB
RUN
1CR
3
1CR
JOG
1M
1CR
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Module 4: Control Relay Applications
This Concludes
Module 4
Control Relay Applications
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Module 5: Timers and Contact Blocks
Module 5
Timers and Contact Blocks
04 - Power and Control Devices
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Module 5: Timers
Timer Types
The concept of using timers in electrical circuits is a very common practice. There are many ways to
utilize timing functions and there are many types of timers. In this section the pneumatic type will be
discussed and illustrated. Below are the two types which are used in common wiring practices. There is
an ON delay type and an OFF delay type. Notice that there are two sets of contacts on each timer. One
set is normally open and the other is normally closed. Above the contacts are shown with dotted lines
between the normally open and normally closed set.
This shows a mechanical connection between each set of
contacts. This dotted line is not indicated on the schematic.
There is a different method of showing that the contacts belong t
o the same device. Once the timer is clipped onto the control relay,
it becomes a timing relay. The designation for that is TR. If it is
the first timer in the circuit, it becomes 1TR. Any contacts used
from this timing relay will be called 1TR. There will be auxiliary
contacts available to be used from this relay part of this timing
relay. These contacts will not have any timing function.
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Module 5: Timers
Timer Types
For an example, if we use a relay that has 2 standard normally open contacts and 2 standard normally
closed contacts as our timing relay, then those contacts will operate just as a control relay. We clip an
ON delay timer on this relay. We have available to use 2 timed contacts, 1 normally open and 1
normally closed.
A timer block can not function without a control relay.
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Module 5: Timers
Pneumatic Timer Operation (Off Delay Type)
Timer Initiation: When the coil is energized, the plunger will be pulled to the left by the movable
magnetic circuit. The movable contact blade will then move from its rest position to the actuated
position. Since the plunger is mechanically linked to the diaphragm, it will move left and compress spring
A. The air contained in Chamber B is transferred into Chamber C through the opening D. This takes
only a short period of time. The contacts change states almost instantaneously from their original
positions. The N.O. contacts will close and the N.C. contacts will open.
Timing Period: When the coil is de-energized, Spring A will push back the diaphragm thus creating a
vacuum in Chamber B. Then the air contained in Chamber C will be forced through a metal filter. The
airflow speed is regulated by a variable length groove fitted between two discs. This timing effect is
obtained by varying the relative position of these two discs. The variation of the discs is made possible
by a setting knob.
Chamber B
Adjustable Disk Channel
Spring A
Plunger Actuated by the
Control Relay
Fixed Disk Channel
Opening D
Daphragm
Filter
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Chamber C
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Module 5: Timers
Pneumatic Timer Operation (Off Delay Type)
End of Timing Period: When the diaphragm returns to its original position, the contact blade snaps to
the off position (rest). The N.C. contacts will close back to the original position and the N.O. contacts
open to the original position.
Chamber B
Adjustable Disk Channel
Spring A
Plunger Actuated by the
Control Relay
Fixed Disk Channel
Opening D
Daphragm
Filter
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Chamber C
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Module 5: Timers
Pneumatic Timer Operation (On Delay Type)
Timer Initiation: This happens when the coil is energized and not de-energized as in the illustration
before. The N.O. contacts remain open and the N.C. contacts remain closed.
Timing Period: When the coil is energized, the timing period begins. During the timing period the
contacts remain in their normal positions.
End of Timing Period: At the end of the timing period the N.O. contacts close and the N.C. contacts
open.
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Module 5: Timers
Pneumatic Timer Symbols and States
Timers
On Delay
At Rest
Contact Configuration
Power On
Power On + Time
Power Off
Power Off + Time
Power Off
Power Off + Time
Coil
Voltage
On
Off
Off Delay
At Rest
Power On
Contact Configuration
Power On + Time
Coil
Voltage
On
Off
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Module 5: Timers
Auxiliary Contact Blocks
Auxiliary blocks are necessary when the control relay or contactor do not have the exact amount of
contacts to do the job. Auxiliary contact blocks can also come in various types and configurations.
Illustrated below is an auxiliary contact block with four sets of contacts and one with two sets of contacts.
The four contact type could be 2 N.O.-2 N.C., or 4 N.O., or 4 N.C. and other variations. The two contact
type could be 1 N.O.-1 N.C. or 2 N.O. or 2 N.C.
As with the timer block, the auxiliary blocks can not function without a control relay or contactor.
53 NO
E
T
61 NC
71 NC
83 NO
53 NO
E
T
Telemechanique
61 NC
Telemechanique
LA1 DN 11
LA1 DN 22
54 NO
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62 NC
72 NC
84 NO
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54 NO
Classification : D3
Classification : D3
62 NC
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Module 5: Timers
This Concludes
Module 5
Timers
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Module 6: Solenoids
Module 6
Solenoids
04 - Power and Control Devices
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Module 6: Solenoids
Understanding Solenoids
Description:
A solenoid is basically just an electrically-controlled valve that uses solenoid action to operate a
mechanical valve. The voltage is applied to the terminals to redirect liquid or air flow. The solenoid
valve usually has two or three ports on it:
The main supply port
The normally open (N.O.) port
The normally closed (N.C.) port
Normal means when power is not applied to the solenoid.
Fundamentally the ports are arranged like this:
A solenoid with only two ports would have either a normally open port or a
normally closed port but not both. There are many other configurations for
ports and piloting. The basic operation is only discussed.
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Module 6: Solenoids
Understanding Solenoids
Description:
So, when the voltage is not applied, liquid or air can flow between the main supply port and the N.O.
port. When voltage is applied, liquid or air can flow between the main supply port and the N.C. port.
How the Solenoid Works
When the voltage is applied to the solenoid coil, an electromagnet is created that moves a valve piston to
direct liquid or air flow through the valve. A spring causes the piston to block the N.C. port until the
voltage is applied to the coil. Then, the force of the electromagnet pulls the piston, closing the N.O. port
and opening the N.C. port.
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Module 6: solenoids
This Concludes
Module 6
Solenoids
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Module 7: Troubleshooting Power and Control Devices
Module 7
Troubleshooting Power and Control Devices
04 - Power and Control Devices
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Module 7: Troubleshooting Power and Control Devices
Troubleshooting Faulty Contactors
In this section we will troubleshoot single direction and forward/reverse contactors with an ohm-meter.
Each person should be allowed to perform these functions on actual devices.
The single direction contactor contains:
A coil, when energized it will change the states of all contacts
Three main contacts (N.O.) used for switching power to the load (motor)
One auxiliary contact (N.O.) used for the seal-in circuit
To troubleshoot this device out of the circuit, the ohm-meter will be used.
Troubleshooting the coil of a single contactor
The ohmic reading for the coil will vary according to the size of the contactor. In this exercise, the
smaller size contactor is demonstrated.
Place the ohm-meter on the A1 and A2 terminals. If the coil is good it should read approximately 100
ohms for a 120v coil, and approximately 6 ohms for a 24v coil.
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Module 7: Troubleshooting Power and Control Devices
Troubleshooting Faulty Contactors
A1
A2
1
3
5
13
L1
L2
L3
NO
A1
L1
L2
L3
A2
T1
T2
T3
13
14
Electrical Representation for a Contactor
2
T1
4
T2
14
6
T3
NO
A2
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Module 7: Troubleshooting Power and Control Devices
Troubleshooting Faulty Contactors
Troubleshooting the main and auxiliary contacts of a single contactor
The ohmic reading for the contacts should be approximately 0 ohms when closed and open loop (OL)
when open.
First, test the contacts for the de-energized operation. Place the ohm-meter on the L1 to T1 terminals. If
the contacts are open, the reading should be OL. Continue to check the other two main contacts, L2 to
T2, then L3 to T3. All should read OL on the ohm-meter. Then check the auxiliary contacts between
terminals 13 and 14. The reading should be OL, also.
To test the contacts for the energized operation, the contactor will need to be manually pressed to
simulate the coil energized. Place the ohm-meter on the L1 to T1 terminals. If the contacts are closed,
the reading should be 0 ohms. Continue to check the other two main contacts, L2 to T2, then L3 to T3.
All should read 0 ohms on the ohm-meter. Then check the auxiliary contacts between terminals 13 and
14. The reading should be 0 ohms, also.
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Module 7: Troubleshooting Power and Control Devices
Troubleshooting Faulty Contactors
A1
A2
1
3
5
13
L1
L2
L3
NO
A1
L1
L2
L3
A2
T1
T2
T3
13
14
Electrical Representation for a Contactor
2
T1
4
T2
14
6
T3
NO
A2
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Module 7: Troubleshooting Power and Control Devices
The Forward/Reverse Contactor
It contains:
One coil for the forward direction and one coil for the reverse direction, when the coils are energized they
will change the states of all contacts
Three main contacts (N.O.) used for switching power to the forward direction
Three main contacts (N.O.) used for switching power to the reverse direction
One auxiliary contact (N.C.) used for the electrical interlock for the forward direction
One auxiliary contact (N.C.) used for the electrical interlock for the reverse direction
To troubleshoot this device out of the circuit, the ohm-meter will be used.
Troubleshooting the coil of the forward/reverse contactor
The ohmic reading for the coil will vary according to the size of the contactor. In this exercise, the
smaller size contactor is demonstrated.
Place the ohm-meter on the A1 and A2 terminals for the forward contactor. If the coil is good it should
read approximately 100 ohms for a 120v coil, and approximately 6 ohms for a 24v coil. Then place the
ohm-meter on the A1 and A2 terminals for the reverse contactor. If the coil is good it should read
approximately 100 ohms for a 120v coil, and approximately 6 ohms for a 24v coil.
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Module 7: Troubleshooting Power and Control Devices
The Forward/Reverse Contactor
A1
A2
A1
A2
1
L1
3
L2
5
L3
21
NC
1
L1
3
L2
5
L3
21
NC
2
T1
4
T2
6
T3
22
NC
2
T1
4
T2
6
T3
22
NC
A2
A1
L1
L2
L3
21
A2
A1
L1
L2
L3
A2
T1
T2
T3
22
A2
T1
T2
T3
Electrical Representation for Fwd Contactor
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21
22
Electrical Representation for Rev Contactor
Classification : D3
Classification : D3
Conservation :
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Module 7: Troubleshooting Power and Control Devices
The Forward/Reverse Contactor
Troubleshooting the main and auxiliary contacts for the forward/reverse contactor
The ohmic reading for the contacts should be approximately 0 ohms when closed and open loop (OL)
when open.
First, test the contacts for the de-energized operation for the
forward contactor. Place the ohm-meter on the L1 to T1 terminals.
If the contacts are open, the reading should be OL.
A1
Continue to check the other two main contacts, L2 to T2.
Then, L3 to T3. All should read OL on the ohm-meter.
Then, check the auxiliary contacts (N.C.) between terminals 21
and 22. The reading should be 0 ohms.
A2
A1
A2
1
L1
3
L2
5
L3
21
NC
1
L1
3
L2
5
L3
2
T1
4
T2
6
T3
22
NC
2
T1
4
T2
6
T3
A2
A1
L1
L2
L3
21
T1
T2
T3
Electrical Representation for Fwd Contactor
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22
NC
A2
A1
L1
L2
L3
A2
T1
T2
T3
22
A2
21
NC
21
22
Electrical Representation for Rev Contactor
Page : ‹#›
Module 7: Troubleshooting Power and Control Devices
The Forward/Reverse Contactor
Next, test the contacts for the de-energized operation for the reverse contactor. Place the ohm-meter on
the L1 to T1 terminals. If the contacts are open, the reading should be OL. Continue to check the other
two main contacts, L2 to T2, then L3 to T3. All should read OL
on the ohm-meter. Then check the auxiliary contacts (N.C.)
between terminals 21 and 22. The reading should be 0 ohms.
To test the contacts for the energized operation, the forward
contactor will need to be manually pressed to simulate the coil
energized. Place the ohm-meter on the L1 to T1 terminals. If the
contacts are closed, the reading should be 0 ohms. Continue to
check the other two main contacts, L2 to T2, then L3 to T3. All
should read 0 ohms on the ohm-meter. Then check the auxiliary
contacts (N.C.) between terminals 21 and 22. The reading should
be OL.
A1
A2
A1
A2
1
L1
3
L2
5
L3
21
NC
1
L1
3
L2
5
L3
2
T1
4
T2
6
T3
22
NC
2
T1
4
T2
6
T3
A2
A1
L1
L2
L3
21
T1
T2
T3
Electrical Representation for Fwd Contactor
04 - Power and Control Devices
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22
NC
A2
A1
L1
L2
L3
A2
T1
T2
T3
22
A2
21
NC
21
22
Electrical Representation for Rev Contactor
Page : ‹#›
Module 7: Troubleshooting Power and Control Devices
The Forward/Reverse Contactor
To test the contacts for the energized operation, the reverse contactor will need to be manually pressed
to simulate the coil energized. Place the ohm-meter on the 1L1 to 1T1 terminals. If the contacts are
closed, the reading should be 0 ohms.
Continue to check the other two main contacts, 1L2 to 1T2.
Then, 1L3 to 1T3. All should read 0 ohms on the ohm-meter.
Then check the auxiliary contacts (N.C.) between terminals 21 and
22. The reading should be OL.
A1
A2
A1
A2
1
L1
3
L2
5
L3
21
NC
1
L1
3
L2
5
L3
2
T1
4
T2
6
T3
22
NC
2
T1
4
T2
6
T3
A2
A1
L1
L2
L3
21
T1
T2
T3
Electrical Representation for Fwd Contactor
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22
NC
A2
A1
L1
L2
L3
A2
T1
T2
T3
22
A2
21
NC
21
22
Electrical Representation for Rev Contactor
Page : ‹#›
Module 7: Troubleshooting Power and Control Devices
Troubleshooting Faulty Control Relays with Auxiliary Contact Blocks
In this section we will troubleshoot control relays with auxiliary contact blocks with an ohm-meter. Each
person should be allowed to perform these functions on actual devices.
The control relay contains:
A coil, when energized it will change the states of all contacts
Four main contacts (2 N.O.) and (2 N.C.) used for switching current and voltage in the control circuit
To troubleshoot this device out of the circuit, the ohm-meter will be used.
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Module 7: Troubleshooting Power and Control Devices
Troubleshooting Faulty Control Relays with Auxiliary Contact Blocks
Troubleshooting the coil
The ohmic reading for the coil will vary according to
the size of the relay. In this exercise, the smaller size
relay is demonstrated.
Place the ohm-meter on the A1 and A2 terminals.
If the coil is good it should read approximately
100 ohms for a 120v coil, and approximately 6 ohms
for a 24v coil.
A1
A2
13
21
NO
NC
31
NC
43
NO
A1
13
21
31
43
14
22
32
44
A2
Electrical Representation for a Relay
14
NO
22
NC
32
NC
44
NO
A2
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Creation date : 02 Nov 2012
Creation date : 08 March 2012
Classification : D3
Classification : D3
Conservation :
Page : ‹#›
Module 7: Troubleshooting Power and Control Devices
Troubleshooting Faulty Control Relays with Auxiliary Contact Blocks
Troubleshooting the main and auxiliary contacts
The ohmic reading for the contacts should be approximately 0 ohms when closed and open loop (OL)
when open.
First, test the contacts for the de-energized operation. Place the ohm-meter on the 13 to 14 (N.O.)
terminals. If the contacts are open, the reading should be OL.
Next, place the ohm-meter on the 21 to 22 (N.C.) terminals. If the contacts are closed the reading
should be 0 ohms. Continue to check the other contacts, 31 to 32 (N.C.), then 43 to 44 (N.O.).
To test the contacts for the energized operation, the relay will need to be manually pressed to simulate
the coil energized. Place the ohm-meter on the 13 to 14 (N.O.) terminals. If the contacts are closed, the
reading should be 0 ohms.
Next, place the ohm-meter on the 21 to 22 (N.C.) terminals. If the contacts are open the reading should
be OL. Continue to check the other contacts, 31 to 32 (N.C.), then 43 to 44 (N.O.).
04 - Power and Control Devices
Presentation : IMS – Tech Managers Conference
Author : IMS Stafff
Author : IMS Staff
Creation date : 02 Nov 2012
Creation date : 08 March 2012
Classification : D3
Classification : D3
Conservation :
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Module 7: Troubleshooting Power and Control Devices
Troubleshooting Faulty Control Relays with Auxiliary Contact Blocks
Next, clip on the auxiliary contact block.
First, test the contacts for the de-energized operation. Place the
ohm-meter on the 53 to 54 (N.O.) terminals. If the contacts are
open, the reading should be OL. Next, place the ohm-meter on
the 61 to 62 (N.C.) terminals. If the contacts are closed the
reading should be 0 ohms. Continue to check the other
contacts, 71 to 72 (N.C.), then 83 to 84 (N.O.).
To test the contacts for the energized operation, the relay will
need to be manually pressed to simulate the coil energized.
Place the ohm-meter on the 53 to 54 (N.O.) terminals. If the
contacts are closed, the reading should be 0 ohms. Next, place
the ohm-meter on the 61 to 62 (N.C.) terminals. If the contacts
are open the reading should be OL. Continue to check the other
contacts, 71 to 72 (N.C.), then 83 to 84 (N.O.).
04 - Power and Control Devices
Presentation : IMS – Tech Managers Conference
Author : IMS Stafff
Author : IMS Staff
Creation date : 02 Nov 2012
Creation date : 08 March 2012
A1
A2
13
21
NO
NC
31
NC
43
NO
A1
13
21
31
43
14
22
32
44
A2
Electrical Representation for a Relay
14
NO
22
NC
32
NC
44
NO
A2
53 NO
E
T
61 NC
71 NC
83 NO
53 NO
E
T
Telemechanique
61 NC
Telemechanique
LA1 DN 11
LA1 DN 22
54 NO
62 NC
72 NC
Classification : D3
Classification : D3
84 NO
54 NO
62 NC
Conservation :
Page : ‹#›
Module 7: Troubleshooting Power and Control Devices
Troubleshooting Faulty Control Relays with Timer Blocks (On and Off Delay)
In this section we will troubleshoot control relays with timer blocks with an ohm-meter. Each person
should be allowed to perform these functions on actual devices. The ON delay timer will be discussed
first.
The control relay contains:
A coil, when energized it will change the states of all contacts
Four main contacts (2 N.O.) and (2 N.C.) used for switching current and voltage in the control circuit
The ON delay timer contains:
One set of timed contacts that are normally open and will time closed after the relay is energized
(N.O.T.C.) and will instantaneously open back up after the relay is de-energized.
One set of timed contacts that are normally closed and will time open after the relay is energized
(N.C.T.O.) and will instantaneously close back after the relay is de-energized.
To troubleshoot this device out of the circuit, the ohm-meter will be used.
04 - Power and Control Devices
Presentation : IMS – Tech Managers Conference
Author : IMS Stafff
Author : IMS Staff
Creation date : 02 Nov 2012
Creation date : 08 March 2012
Classification : D3
Classification : D3
Conservation :
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Module 7: Troubleshooting Power and Control Devices
Troubleshooting Faulty Control Relays with Timer Blocks (On and Off Delay)
Troubleshooting the coil
The coil should be tested using the same procedure as before for
the contactors and relays.
A1
Troubleshooting the ON delay timed contacts:
First, test the timed contacts for the de-energized operation. Place
the ohm-meter on the 67 to 68 (N.O.T.C.) terminals. If the contacts
are open, the reading should be OL.
A2
13
21
NO
NC
31
NC
43
NO
A1
13
21
31
43
14
22
32
44
A2
Electrical Representation for a Relay
14
NO
Next, place the ohm-meter on the 55 to 56 (N.C.T.O.) terminals.
If the contacts are closed the reading should be 0 ohms.
22
NC
32
NC
44
NO
A2
67
55
NC
NO
E
T
NO
LA2 DT 2
04 - Power and Control Devices
Presentation : IMS – Tech Managers Conference
Author : IMS Stafff
Author : IMS Staff
Creation date : 02 Nov 2012
Creation date : 08 March 2012
Classification : D3
Classification : D3
NC
E
T
Telemechanique
LA3 DR 2
ON DELAY
0.1 - 3s
56
65
57
Telemechanique
OFF DELAY
0.1 - 30s
68
58
Conservation :
66
Page : ‹#›
Module 7: Troubleshooting Power and Control Devices
Troubleshooting Faulty Control Relays with Timer Blocks (On and Off Delay)
Next, test the contacts for the energized operation. Place the
ohm-meter on the 67 to 68 (N.O.T.C.) terminals. The reading should
still be OL. Press the timing relay in to simulate the coil energized.
The timed contacts should close after the time dialed on the timer.
When the timed contacts close, the reading should be 0 ohms.
Release the timing relay and the contacts should open immediately.
The reading should go back to OL.
Next, place the ohm-meter on the 55 to 56 (N.C.T.O.) terminals. If
the contacts are closed the reading should be 0 ohms. Press the
timing relay in to simulate the coil energized. The timed contacts
should open after the time dialed on the timer. When the timed
contacts open, the reading should be OL. Release the timing relay
and the contacts should close immediately. The reading should go
back to 0 ohms.
04 - Power and Control Devices
Presentation : IMS – Tech Managers Conference
Author : IMS Stafff
Author : IMS Staff
Creation date : 02 Nov 2012
Creation date : 08 March 2012
A1
A2
13
21
NO
NC
31
NC
43
NO
A1
13
21
31
43
14
22
32
44
A2
Electrical Representation for a Relay
14
NO
22
NC
32
NC
44
NO
A2
67
55
NC
NO
E
T
NO
LA2 DT 2
Classification : D3
Classification : D3
NC
E
T
Telemechanique
LA3 DR 2
ON DELAY
0.1 - 3s
56
65
57
Telemechanique
OFF DELAY
0.1 - 30s
68
58
Conservation :
66
Page : ‹#›
Module 7: Troubleshooting Power and Control Devices
Troubleshooting Faulty Control Relays with Timer Blocks (On and Off Delay)
The OFF delay timer will be discussed next.
The control relay contains:
A coil, when energized it will change the states of all contacts
Four main contacts (2 N.O.) and (2 N.C.) used for switching current and voltage in the control circuit
The OFF delay timer contains:
One set of timed contacts that are normally open, will close instantaneously when the timing relay is
energized and will time back open after the relay is de-energized (N.O.T.O.).
One set of timed contacts that are normally closed, will open instantaneously when the timing relay is
energized and will time back closed after the relay is de-energized (N.C.T.C.).
To troubleshoot this device out of the circuit, the ohm-meter will be used.
Troubleshooting the coil
The coil should be tested using the same procedure as before for the contactors and relays.
04 - Power and Control Devices
Presentation : IMS – Tech Managers Conference
Author : IMS Stafff
Author : IMS Staff
Creation date : 02 Nov 2012
Creation date : 08 March 2012
Classification : D3
Classification : D3
Conservation :
Page : ‹#›
Module 7: Troubleshooting Power and Control Devices
Troubleshooting Faulty Control Relays with Timer Blocks (On and Off Delay)
Troubleshooting the OFF delay timed contacts
First, test the timed contacts for the de-energized operation before
the timing relay has been energized. Place the ohm-meter on the
57 to 58 (N.O.T.O.) terminals. If the contacts are open, the reading
should be OL. Next, place the ohm-meter on the 65 to 66 (N.C.T.C.)
terminals. If the contacts are closed the reading should be 0 ohms.
A1
A2
13
21
NO
NC
31
NC
43
NO
A1
13
21
31
43
14
22
32
44
Next, test the contacts for the energized then de-energized operation. Place the ohm-meter on the 57 to
58 (N.O.T.O.) terminals. The reading should still be OL. Press the
timing relay in to simulate the coil energized. The timed contacts
should close instantaneously. The reading should be 0 ohms.
Release the timing relay and the timed contacts (N.O.T.O.) should
open after the time dialed on the timer. When the timed contacts
open, the reading should be OL.
A2
Electrical Representation for a Relay
14
NO
22
NC
32
NC
44
NO
A2
67
55
NC
NO
E
T
65
57
NO
NC
E
T
Telemechanique
Telemechanique
LA2 DT 2
LA3 DR 2
ON DELAY
0.1 - 3s
56
04 - Power and Control Devices
Presentation : IMS – Tech Managers Conference
Author : IMS Stafff
Author : IMS Staff
Creation date : 02 Nov 2012
Creation date : 08 March 2012
Classification : D3
Classification : D3
OFF DELAY
0.1 - 30s
68
58
Conservation :
66
Page : ‹#›
Module 7: Troubleshooting Power and Control Devices
Troubleshooting Faulty Solenoids
In this section we will troubleshoot solenoids an ohm-meter. Each person should be allowed to perform
these functions on actual devices.
The solenoid contains:
A coil, when energized it will change the position of the mechanical valve
The mechanical valve which could be normally open or normally closed, or both.
A mechanical override is supplied with some valves
To troubleshoot this device out of the circuit, the ohm-meter will be used.
Troubleshooting the coil
The ohmic reading for the coil will vary according to the size of the solenoid. In this exercise, the smaller
size solenoid is demonstrated.
Place the ohm-meter on the terminals of the solenoid. If the coil is good it should read approximately
100 ohms for a 120v coil, and approximately 6 ohms for a 24v coil.
04 - Power and Control Devices
Presentation : IMS – Tech Managers Conference
Author : IMS Stafff
Author : IMS Staff
Creation date : 02 Nov 2012
Creation date : 08 March 2012
Classification : D3
Classification : D3
Conservation :
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Module 7: Troubleshooting Power and Control Devices
Troubleshooting Faulty Solenoids
Troubleshooting the mechanical operation of the valve
If the valve is supplied with a mechanical override, operate the override to check the mechanical
operation. If the valve is not supplied with a mechanical override, the appropriate voltage for the coil
should be applied to the solenoid coil to check the mechanical operation.
04 - Power and Control Devices
Presentation : IMS – Tech Managers Conference
Author : IMS Stafff
Author : IMS Staff
Creation date : 02 Nov 2012
Creation date : 08 March 2012
Classification : D3
Classification : D3
Conservation :
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Module 7: Troubleshooting Power and Control Devices
This Concludes
Module 7
Troubleshooting Power and Control Devices
04 - Power and Control Devices
Presentation : IMS – Tech Managers Conference
Author : IMS Stafff
Author : IMS Staff
Creation date : 02 Nov 2012
Creation date : 08 March 2012
Classification : D3
Classification : D3
Conservation :
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