Transcript here - Eaton Corporation

Often Overlooked Problems
When Applying Automatic
Transfer Switches in
Institutions
David G. Loucks, P.E.
[email protected]
Eaton Corporation
© 2005 Eaton Corporation. All rights reserved.
We Will Cover:
1. Changes Forcing Us To Rethink Our Designs
1. Utility
2. Our Facilities
2. Need To Improve System Reliability
1. Selectivity / Coordination
2. Withstand / Short-Time
3. X/R ratings
3. “Optional Systems”
1. Unique Add-On Solutions
2
Changes:
Background Survey



1. How to Insure
You Have It
2. How to Improve
What You Have
Electrical Utility Grid reliability or lack thereof
Increased dependency in hospital on computer
based devices
Aging infrastructure – capacity, reliability,
maintenance cost, parts availability, safety

Arc flash

Saving money; Reducing energy consumptions
3
Changes:
Background Survey



Utility Grid reliability or lack thereof
Increased dependency in hospital on computer
based devices
Aging infrastructure – capacity, reliability,
maintenance cost, parts availability, safety

Arc flash

Saving money; Reducing energy consumptions
Important Topics, but won’t be covered today
4
Okay, So What Affects Electrical
Grid Reliability?





Surge Protection and Grounding
Harmonics, Power Factor Correction &
Electromagnetic interference
Back-up Power and Voltage Stabilization (Power
Conditioning)
Monitoring and Diagnostic Systems (Early
Warning)
Human Issues
5
During Today’s Webinar We Will
Focus on This Issue





Surge Protection and Grounding
Harmonics, Power Factor Correction &
Electromagnetic interference
Back-up Power and Voltage Stabilization (Power
Conditioning)
Monitoring and Diagnostic Systems (Early
Warning)
Human Issues
6
How To Recognize You Have a
Voltage Stability Problem

Problems / Symptoms – what problems can occur

Computer reboots / lock-ups

Lights flickering

Loss of revenue

User inconvenience & rescheduling

Diagnostic equipment recalibration requirements

Lost or destroyed samples / data / research

(Medical) Increased patient suffering

Data integrity

HVAC / comfort

Safety (biohazard, falls)

Increased equipment repair costs
7
What Causes Voltage Instability?







Miscoordination of protective equipment
System overload
(Hospital) Lack of isolation panels – wet areas,
gases
Utility outages / natural disaster (i.e. Northeast
blackout; weather issues; lack of fuel)
Human error
Bad batteries / battery failure
Poor maintenance
8
Since our discussion deals with
generators and ATS, we will cover:







Miscoordination of protective equipment
System overload
(Hospital) Lack of isolation panels – wet areas,
gases
Utility outages / natural disaster (i.e. Northeast
blackout; weather issues; lack of fuel)
Human error
Bad batteries / battery failure
Poor maintenance
9
TESTING STANDARDS

UL1008 ATS Standard

UL489

UL1087 MCS Standard

UL1066 PCB Standard

UL891

UL1558 LV Switchgear Standard

Q.A. CERTIFICATE
MCCB Standard
LV Switchboard Standard

50 Operations Minimum

Internal Production Standard
10
Low Voltage Power Circuit
Breakers



ANSI C37.13 IEEE Standard for Low-Voltage
AC Power Circuit Breakers Used in Enclosures
ANSI C37.16 Low-Voltage Power Circuit
Breakers and AC Power Circuit Protectors Preferred Ratings, Related Requirements, and
Application Recommendations
ANSI C37.17 Trip Devices for AC and General
Purpose DC Low-Voltage Power Circuit Breakers
11
Healthcare: JCAHO EC.2.10.4.1
…testing each generator 12 times a year with testing
intervals not less than 20 days and not more than 40
days. These tests shall be conducted for at least 30
continuous minutes under a dynamic load that is at least
30% of the nameplate rating of the generator.
If diesel-powered generators do not meet the minimum
exhaust gas temperatures as determined during these
tests, they shall be exercised for 30 continuous minutes
at the intervals described above with available EPSS
load, and exercised annually with supplemental loads of
•
•
•
25 percent of nameplate rating for 30 minutes, followed by
50 percent of nameplate rating for 30 minutes, followed by
75 percent of nameplate rating for 60 minutes for a total of two
continuous hours.
12
Other Applicable Standards

NFPA 99


NFPA 110


“Standards for Healthcare Facilities”
“Standards for Emergency and Standard Power
Systems”
IEEE 1547 Utility Interconnect Standard (NEW)


Only applies if 10 MW or smaller (if larger, custom
utility review required)
Only if “Make-Before-Break” closed transition for more
than 1/10 second with utility
13
Transfer Switches for Emergency
Systems


NEC Article 700
Legally required to automatically provide
alternate power, within 10 seconds of power
interruption, to a number of prescribed functions
essential for the safety of human life
14
Transfer Switches for
Legally Required Standby Systems



NEC Articles 701
Intended to automatically supply power to
selected loads (other than those classed as
emergency systems) in the event of failure of the
normal source
Power available 60 seconds after outage
15
Transfer Switches for
Optional Standby Systems


NEC Articles 702
Intended to supply power, either automatically or
non-automatically to selected loads other than
those classed as emergency or legally required
standby
16
Miscoordination

Selective Coordination



Upstream and downstream breakers
•
Phase
•
Ground
ATS withstand

Magnitude

Duration

Asymmetry (X/R)
ATS short-time rating
17
Healthcare Ground Fault
Protection -- NEC 517.17


… an additional step of ground-fault protection
shall be provided in the next level of feeder
disconnecting means downstream toward the
load.
The additional levels of ground-fault protection
shall not be installed as follows:


(1) On the load side of an essential electrical system
transfer switch
(2) Between the on-site generating unit(s) described in
517.35(B) and the essential electrical system transfer
switch(es)
18
Healthcare Ground Fault
Protection – UL 1008 Article 20
Exception No. 3: Ground-fault protection need
not be provided on that side of a transfer switch
intended for connection to the alternate source,
provided that the transfer switch is marked in
accordance with 41.50.
19
2002 NEC 517.17
Ground-Fault Protection
B) Selectivity. Ground-fault protection for
operation of the service and feeder
disconnecting means shall be fully selective
such that the feeder device and not the
service device shall open on ground faults
on the load side of the feeder device. A sixcycle minimum separation between the
service and feeder ground-fault tripping
bands shall be provided.
20
UL 1008 - ATS Withstand and Fault
Closing Ratings




Transfer switch must withstand the designated
level of short-circuit current until the overcurrent
protective devices open (unless integral to the
design)
Test current specified in terms of the required
symmetrical amperes and the power factor of the
test current
Test current maintained for at least three cycles
(50 ms)
Same sample used for the closing test
21
Definitions
Interrupting capacity
The Maximum Short Circuit Current that the
Device Can Safely Interrupt
Short-time current rating
Defines the Ability of the Device to Remain
Closed for a Time Interval Under High Fault
Current Conditions
22
NEC 517.17 Says Your Upstream
Device Must Remain Closed For…
B) Selectivity. Ground-fault protection for
operation of the service and feeder disconnecting
means shall be fully selective such that the feeder
device and not the service device shall open on
ground faults on the load side of the feeder
device. A six-cycle minimum separation between
the service and feeder ground-fault tripping bands
shall be provided.
23
How Long Does UL1008 Say ATS
Must Withstand Fault?
UL1008
34 Withstand
34.1 When tested under the conditions described in
34.2 – 34.15, a transfer switch shall withstand the
designated levels of current until the overcurrent
protective devices open or for a time as designated
in 34.3. At the conclusion of the test….
34.5 The test current is to be maintained for at least
3 cycles (50 ms). See 41.20.
24
To Achieve Selectivity, You Need
To Delay Upstream Device



A six-cycle separation between service and
feeder means that at any current level, the
downstream device must clear the fault 6-cycles
(0.1 sec) faster than the upstream device.
If the fault current is high, the downstream device
might be clearing it in 0.02 seconds (~1 cycle)
That means the upstream must delay tripping for
6+1 = 7 cycles = 0.12 seconds
25
Can an ATS Withstand a Fault for
0.12 seconds?


Not if the switch is only UL1008 rated for 3cycles.
“Houston, we have a problem…”
26
Fast Forward to 2002:
New UL1008 41.20.1 Short-Time
3 Cycle ATS
41.20 A transfer switch tested for three cycles shall be marked, When
protected by a circuit breaker without an adjustable short-time response
only or by fuses this transfer switch is rated for use on a circuit capable
of delivering not more than ____ rms symmetrical amperes, ____ volts
maximum.The value of amperes shall correspond to the symmetrical
values given in 41.23. See 34.5 and 34.6. Revised 41.20 effective September 18, 1997
Short-Time Rated ATS
41.20.1 A transfer switch determined to comply with the Short-Time
Current Rating Test, Section 36A, shall be marked, This transfer switch
is intended for use with an upstream circuit breaker having a short-time
rating not exceeding _______ volts at ______ amperes, for _______
cycles (seconds).The values of amperes, and cycles (seconds) shall
be as specified by the manufacturer. 41.20.1 added January 9, 2002
27
Choose Carefully


Make sure your ATS can survive 6-cycles of fault
current
UL1008 ATS Standard




All are tested to 3-cycles at their withstand current
UL1008 28.1-28.6 says that ATS tested to 6 times
rated current for 10 cycles
If your calculated fault current is greater than 6x ATS
rating, you need an ATS with a short-time rating
May also need to review your distribution equipment
•
UL891 Switchboards/UL489 Devices (3-cycle rated)
•
UL1558 Switchgear/UL1066 Devices (30-cycle rated)
28
Power Factor
Withstand and Closing
Rating
(rms symmetrical
amperes)
10,000 or less
10,001 - 20,000
Greater than 20,000
UL 1008
Maximum Test
Power Factor
NEMA
Maximum Test
Power Factor
Minimum
Corresponding
X/R Ratio
0.40 - 0.50
0.25 - 0.30
0.20 or less
0.50
0.30
0.20
1.73
3.18
4.90
29
X/R Ratio
30
X/R Ratio - ANSI Test
X/R = 0, PF = 1.0 (symmetry) X/R = 6.6, PF = 0.15 (asymmetry)
Current in Per Unit
20
15
10
5
0
0
1
2
3
4
-5
-10
Time in Cycles
31
X/R Ratio - Application Data
UL1008 takes these values into consideration, so ATS is okay
…but when specifying generator breaker make sure you are aware of these derating factors
32
X/R Ratio - Application Data
Peak Multiplication Factor Calculations
Z
X

R
X/R = tan 
= tan-1(X/R)
R/Z = cos  = PF
 = cos-1(PF)
X/R = tan(cos-1(PF))
PF = cos(tan-1(X/R))
33
LVPCB Application –
Large Source KVA
G
At 2500KVA
I (sc) = 64,300A
Utility
4000 A
PCB
1600 A
PCB
4000 A PCB (Static Trip – LS)
Frame:
4000(Static
A, Sensor:
4000
A PCB
Trip 4000
– LS)
LTPU: 4000
0.8 A, Sensor:
LTD: 2.0
sec.
Frame:
4000
STPU: 0.8
2.0
STD: 2.0
0.4 sec.
sec.
LTPU:
LTD:
No Instantaneous
Trip 0.4 sec.
STPU:
2.0
STD:
No Instantaneous Trip
1600 A PCB (Static Trip – LS)
Frame:
1600(Static
A, Sensor:
1600
A PCB
Trip 1600
– LS)
LTPU:
1.0
LTD:
4.0
sec.
Frame: 1600 A, Sensor: 1600
STPU: 1.0
2.0
STD: 4.0
0.2sec.
sec.
LTPU:
LTD:
No Instantaneous
Trip 0.2 sec.
STPU:
2.0
STD:
1600 A
PCB
1600 A ATS
800 A
PCB
600 A
MCB
No Instantaneous Trip
800 A PCB (Static Trip – LS)
Frame:
800(Static
A, Sensor:
800
A PCB
Trip 800
– LS)
LTPU: 800
1.0 A, Sensor:
LTD: 7.0
Frame:
800sec.
STPU: 1.0
3.0
STD: 7.0
0.1 sec.
sec.
LTPU:
LTD:
No Instantaneous
Trip 0.1 sec.
STPU:
3.0
STD:
No Instantaneous Trip
600 A MCB (Thermal -Magnetic,
Frame:
600 (Thermal
A, Trip: -600
A
600
A MCB
Magnetic,
Instantaneous
5*T=3000
Frame:
600 A,PU:
Trip:
600 A A
34
Typical Distribution System System
-- Possible Fault Locations -Gen 1
Utility
> 1000 A
> 150 VLN
CB1
CB2
F1
S1
S2
control
logic
F2
F3
35
Fault Cleared by Upstream Device
Gen 1
Utility
Event
Breaker Type
Contactor Type
Comparison
Between Designs
> 1000 A
> 150 VLN
CB1
CB2
F1
S1
S2
control
logic
36
Fault Cleared by Upstream Device
Gen 1
Utility
Event
Breaker Type
Contactor Type
Comparison
Between Designs
(F1) Fault on load
side of CB1 (line
side of ATS)
> 1000 A
> 150 VLN
CB1
CB2
F1
S1
S2
control
logic
37
Fault Cleared by Upstream Device
Gen 1
Utility
> 1000 A
> 150 VLN
CB1
Event
Breaker Type
Contactor Type
(F1) Fault on load
side of CB1 (line
side of ATS)
Fault drops S1
voltage to low
value
Fault drops S1
voltage to low
value
Comparison
Between Designs
Same
CB2
F1
S1
S2
control
logic
38
Fault Cleared by Upstream Device
Gen 1
Utility
> 1000 A
> 150 VLN
Trips!
CB1
CB2
Comparison
Between Designs
Event
Breaker Type
Contactor Type
(F1) Fault on load
side of CB1 (line
side of ATS)
Fault drops S1
voltage to low
value
Fault drops S1
voltage to low
value
Same
CB1 opens
S1 voltage drops
to zero
S1 voltage drops
to zero
Same
F1
S1
S2
control
logic
39
Fault Cleared by Upstream Device
Gen 1
Utility
> 1000 A
> 150 VLN
CB1
S1
Event
Breaker Type
Contactor Type
(F1) Fault on load
side of CB1 (line
side of ATS)
Fault drops S1
voltage to low
value
Fault drops S1
voltage to low
value
Same
CB1 opens
S1 voltage drops
to zero
S1 voltage drops
to zero
Same
CB2
ATS calls for Gen
1 start
F1
Comparison
Between Designs
-
-
Same
S2
control
logic
40
Fault Cleared by Upstream Device
Gen 1
Utility
> 1000 A
> 150 VLN
CB1
S1
Event
Breaker Type
Contactor Type
(F1) Fault on load
side of CB1 (line
side of ATS)
Fault drops S1
voltage to low
value
Fault drops S1
voltage to low
value
Same
CB1 opens
S1 voltage drops
to zero
S1 voltage drops
to zero
Same
CB2
ATS calls for Gen
1 start
F1
S2
control
logic
Comparison
Between Designs
ATS transfers to
S2
Voltage appears
on S2
Voltage appears
on S2
Same
Same
System Functioning Normally
41
Fault Moved to Load Side of ATS
Gen 1
Utility
> 1000 A
> 150 VLN
CB1
CB2
S1
S2
control
logic
F2
42
Fault Moved to Load Side of ATS
Gen 1
Utility
Event
Breaker Type
Contactor Type
Comparison
Between Designs
> 1000 A
> 150 VLN
CB1
CB2
S1
S2
control
logic
F2
43
Fault Moved to Load Side of ATS
Gen 1
Utility
> 1000 A
> 150 VLN
CB1
Event
Breaker Type
Contactor Type
(F2) Fault on load
side ATS)
Fault drops S1
voltage to low
value
Fault drops S1
voltage to low
value
Comparison
Between Designs
Same
CB2
S1
S2
control
logic
F2
44
Fault Moved to Load Side of ATS
Gen 1
Utility
> 1000 A
> 150 VLN
Trips!
CB1
CB2
S1
Comparison
Between Designs
Event
Breaker Type
Contactor Type
(F2) Fault on load
side ATS)
Fault drops S1
voltage to low
value
Fault drops S1
voltage to low
value
Same
CB1 opens
S1 voltage drops
to zero
S1 voltage drops
to zero
Same
S2
control
logic
F2
45
Fault Moved to Load Side of ATS
Gen 1
Utility
> 1000 A
> 150 VLN
CB1
Event
Breaker Type
Contactor Type
(F2) Fault on load
side ATS)
Fault drops S1
voltage to low
value
Fault drops S1
voltage to low
value
Same
CB1 opens
S1 voltage drops
to zero
S1 voltage drops
to zero
Same
CB2
ATS calls for Gen
1 start
S1
Comparison
Between Designs
-
-
Integrated selfprotects
S2
control
logic
F2
46
Fault Moved to Load Side of ATS
Gen 1
Utility
> 1000 A
> 150 VLN
CB1
Event
Breaker Type
Contactor Type
(F2) Fault on load
side ATS)
Fault drops S1
voltage to low
value
Fault drops S1
voltage to low
value
Same
CB1 opens
S1 voltage drops
to zero
S1 voltage drops
to zero
Same
CB2
ATS calls for Gen
1 start
S1
S2
Comparison
Between Designs
ATS transfers to
S2
Voltage appears
on S2
Voltage appears
on S2
Integrated selfprotects
Integrated selfprotects
control
logic
F2
47
Fault Moved to Load Side of ATS
Gen 1
Utility
> 1000 A
> 150 VLN
Trips!
CB1
Event
Breaker Type
Contactor Type
(F2) Fault on load
side ATS)
Fault drops S1
voltage to low
value
Fault drops S1
voltage to low
value
Same
CB1 opens
S1 voltage drops
to zero
S1 voltage drops
to zero
Same
CB2
ATS calls for Gen
1 start
S1
S2
control
logic
Comparison
Between Designs
-
-
Integrated selfprotects
ATS transfers to
S2
Voltage appears
on S2
Voltage appears
on S2
Integrated selfprotects
CB2 opens
Closing into fault
trips CB2
Closing into fault
trips CB2
Integrated selfprotects
F2
48
Fault Moved to Load Side of ATS
Gen 1
Utility
> 1000 A
> 150 VLN
CB1
Event
Breaker Type
Contactor Type
(F2) Fault on load
side ATS)
Fault drops S1
voltage to low
value
Fault drops S1
voltage to low
value
Same
CB1 opens
S1 voltage drops
to zero
S1 voltage drops
to zero
Same
CB2
ATS calls for Gen
1 start
S1
S2
control
logic
F2
Comparison
Between Designs
-
-
Integrated selfprotects
ATS transfers to
S2
Voltage appears
on S2
Voltage appears
on S2
Integrated selfprotects
CB2 opens
Closing into fault
trips CB2
Closing into fault
trips CB2
Integrated selfprotects
No power to load
Both sources
tripped
Both sources
tripped
Same
System Functioning Normally,
but after F2 fixed, CB1 and CB2 must be reset and
reclosed
49
Alternate Design: Communications
with Upstream Overcurrent Device
Gen 1
Utility
> 1000 A
> 150 VLN
Phase
CB1
CB2
trip
unit
S1
S2
control
logic L.O.
F2
50
Alternate Design: Communications
with Upstream Overcurrent Device
Gen 1
Utility
Event
Breaker Type
(with integrated
OC protection)
Contactor Type
Comparison
Between Designs
> 1000 A
> 150 VLN
Phase
CB1
CB2
trip
unit
S1
S2
control
logic L.O.
F2
51
Alternate Design: Communications
with Upstream Overcurrent Device
Gen 1
Utility
Event
Breaker Type
Contactor Type
Comparison
Between Designs
Fault drops S1
voltage to low
value
Same
(with integrated
OC protection)
> 1000 A
> 150 VLN
(F2) Fault on load
side ATS)
Phase
CB1
Fault drops S1
voltage to low
value
CB2
trip
unit
S1
S2
control
logic L.O.
F2
52
Alternate Design: Communications
with Upstream Overcurrent Device
Gen 1
Utility
Event
Breaker Type
Contactor Type
Comparison
Between Designs
(with integrated
OC protection)
> 1000 A
> 150 VLN
Trips!
Phase
CB1
trip
unit
S1
CB2
(F2) Fault on load
side ATS)
Fault drops S1
voltage to low
value
Fault drops S1
voltage to low
value
Same
CB1 opens
S1 voltage drops
to zero
S1 voltage drops
to zero
Same
S2
control
logic L.O.
F2
53
Alternate Design: Communications
with Upstream Overcurrent Device
Gen 1
Utility
Event
Breaker Type
Contactor Type
Comparison
Between Designs
(with integrated
OC protection)
> 1000 A
> 150 VLN
Phase
CB1
CB2
trip
unit
S1
(F2) Fault on load
side ATS)
Fault drops S1
voltage to low
value
Fault drops S1
voltage to low
value
Same
CB1 opens
S1 voltage drops
to zero
S1 voltage drops
to zero
Same
ATS detects phase
fault and locks out
Locked out (but
ready)
-
Same
S2
control
logic L.O.
F2
54
Alternate Design: Communications
with Upstream Overcurrent Device
Gen 1
Utility
Event
Breaker Type
Contactor Type
Comparison
Between Designs
(with integrated
OC protection)
> 1000 A
> 150 VLN
Phase
CB1
CB2
trip
unit
S1
(F2) Fault on load
side ATS)
Fault drops S1
voltage to low
value
Fault drops S1
voltage to low
value
Same
CB1 opens
S1 voltage drops
to zero
S1 voltage drops
to zero
Same
ATS detects phase
fault and locks out
Locked out (but
ready)
-
Same
S2
control
logic L.O.
System Functioning Normally,
Integrated OC ATS will not try to close into
downstream fault
F2
55
Fault Moved to Load Side of
Downstream Feeder Breaker
Gen 1
Utility
> 1000 A
> 150 VLN
CB1
CB2
S1
S2
control
logic
CB3
CB4
CB5
F3
56
Fault Moved to Load Side of
Downstream Feeder Breaker
Gen 1
Utility
> 1000 A
> 150 VLN
CB1
Event
Breaker Type
Contactor Type
(F3) Fault on load
side of CB3
S1 voltage drops
(related to
distance to F3
fault)
S1 voltage drops
(related to
distance to F3
fault)
Comparison
Between Designs
Same
CB2
S1
S2
control
logic
CB3
CB4
CB5
F3
57
Fault Moved to Load Side of
Downstream Feeder Breaker
Gen 1
Utility
> 1000 A
> 150 VLN
CB1
CB2
S1
Comparison
Between Designs
Event
Breaker Type
Contactor Type
(F3) Fault on load
side of CB3
S1 voltage drops
(related to
distance to F3
fault)
S1 voltage drops
(related to
distance to F3
fault)
Same
CB5 opens
CB3, CB4 loads
continue with
power
CB3, CB4 loads
continue with
power
Same
S2
control
logic
CB3
CB4
Trips!
CB5
F3
58
Fault Moved to Load Side of
Downstream Feeder Breaker
Gen 1
Utility
> 1000 A
> 150 VLN
CB1
CB2
S1
Event
Breaker Type
Contactor Type
(F3) Fault on load
side of CB3
S1 voltage drops
(related to
distance to F3
fault)
S1 voltage drops
(related to
distance to F3
fault)
Same
CB5 opens
CB3, CB4 loads
continue with
power
CB3, CB4 loads
continue with
power
Same
Power is
maintained to CB3
and CB4
S2
Comparison
Between Designs
-
-
Same
control
logic
CB3
CB4
CB5
System Functioning Normally, only loads connected
to CB5 are affected
F3
59
ATS Response to Various Faults
Location of
Disturbance
Type of
Disturbance
CB1
Response
CB3
Response
Instantaneous Trip
Molded Case Switch
ATS Response
Magnum ATS
Response
Contactor Type ATS
Response
F1
Overload
Trip
Nothing
Start Gen, Transfer
Start Gen, Transfer
Start Gen, Transfer
Short Circuit
Trip
Nothing
Start Gen, Transfer
Start Gen, Transfer
Start Gen, Transfer
GF
Trip
Nothing
Start Gen, Transfer
Start Gen, Transfer
Start Gen, Transfer
Overload
Trip
Nothing
Start Gen, Transfer
Start Gen, Transfer
Start Gen, Transfer
Short Circuit
Trip
Nothing
Start Gen, Transfer
Start Gen, Transfer
Start Gen, Transfer
GF
Trip
Nothing
Start Gen, Transfer
Start Gen, Transfer
Start Gen, Transfer
Overload
Nothing
Trip
No Transfer
No Transfer
No Transfer
Short Circuit
(low magnitude)
Nothing
Trip
No Transfer
No Transfer
No Transfer
Short Circuit
(high magnitude)
Trip/
Nothing1
Trip
Start Gen, Transfer
or No Transfer2
Start Gen, Transfer
or No Transfer2
Start Gen, Transfer
or No Transfer2
GF (low
magnitude)
Nothing/
Trip3
Nothing/
Trip4
Start Gen, Transfer
or No Transfer5
Start Gen, Transfer
or No Transfer5
Start Gen, Transfer
or No Transfer5
GF (high
magnitude)
Trip/
Nothing6
Trip
Start Gen, Transfer
or No Transfer7
Start Gen, Transfer
or No Transfer7
Start Gen, Transfer
or No Transfer7
F2
F3
60
Notes
1.
2.
3.
4.
5.
6.
7.
If the CB1 breaker does not have short-time delay, and the fault
magnitude is within its instantaneous range, CB1 will trip.
If CB1 trips, ATS will interpret that as loss of Source 1, start
generator and attempt to transfer. If fault remains, generator will
close into fault and trip generator breaker (CB2).
If only breaker upstream of GF is utility main (CB1), it will trip.
If CB3 has GF protection, and that GF protection is selectively
coordinated with CB1 (as it should be), CB3 will trip and isolate the
GF, CB1 will not trip and the generator will not start and transfer.
If CB1 trips due to GF, the generator will start and transfer. Since
the generator breaker does not require GF protection and since the
GF is a “low magnitude” (i.e. below phase trip), generator will
source power without tripping.
If CB1 does not have a time delay for ground fault trip, it may trip
on a high magnitude GF.
If CB1 trips, the generator starts and transfers.
61
UL1008 20.1 GF Protection
Utility
Gen 1
B1
S1
B2
S2
control
logic
62
GF Protection
Gen 1
Utility
> 1000 A
> 150 VLN
CB1
S1
CB2
S2
control
logic
63
GF Protection
Gen 1
Utility
> 1000 A
> 150 VLN
GF
required
CB1
S1
CB2
No GF
required
S2
control
logic
64
GF Protection
Gen 1
Utility
> 1000 A
> 150 VLN
1.
GF
required
CB1
S1
CB2
Ground fault on system
No GF
required
S2
control
logic
65
GF Protection
Gen 1
Utility
> 1000 A
> 150 VLN
Trip!
CB1
S1
CB2
No GF
required
1.
Ground fault on systems
2.
B1 trips on GF, ATS loses S1, Gen 1
starts
S2
control
logic
66
GF Protection
Gen 1
Utility
> 1000 A
> 150 VLN
Trip!
CB1
S1
CB2
S2
control
logic
No GF
required
1.
Ground fault on systems
2.
B1 trips on GF, ATS loses S1, Gen 1
starts
3.
Transfers load to Gen 1. Depending
on type of ground, 1 of 2 things
happens:
67
GF Protection
Gen 1
Utility
> 1000 A
> 150 VLN
Trip!
CB1
S1
1.
Ground fault on systems
2.
B1 trips on GF, ATS loses S1, Gen 1
starts
3.
Transfers load to Gen 1. Depending
on type of ground, 1 of 2 things
happens:
CB2
S2
control
logic
•
GF current below phase trip:
S2 remains closed
68
GF Protection
Gen 1
Utility
> 1000 A
> 150 VLN
Trip!
CB1
S1
1.
Ground fault on systems
2.
B1 trips on GF, ATS loses S1, Gen 1
starts
3.
Transfers load to Gen 1. Depending
on type of ground, 1 of 2 things
happens:
CB2
S2
control
logic
•
GF current above phase trip:
S2 Trips! – No power to load
69
GF Protection
Gen 1
Utility
What if the process were
1. Ground fault on systems
repeated, except
had
2. B1 that
trips on GF, we
ATS loses
S1, Gen 1
starts
a phase to phase
fault
3. Transfers
load to Genthis
1. Depending
on type of ground, 1 of 2 things
happens:
time?
> 1000 A
> 150 VLN
Trip!
B1
S1
B2
S2
control
logic
•
GF current above phase trip:
S2 Trips! – No power to load
70
Phase Protection
Gen 1
Utility
What if the process were
1. Ground fault on systems
repeated, except
had
2. B1 that
trips on GF, we
ATS loses
S1, Gen 1
starts
a phase to phase
fault
3. Transfers
load to Genthis
1. Depending
on type of ground, 1 of 2 things
happens:
time?
> 1000 A
> 150 VLN
Trip!
B1
S1
B2
S2
control
logic
•
GF current above phase trip:
S2 Trips! – No power to load
71
Phase Protection
Gen 1
Utility
> 1000 A
> 150 VLN
1.
Phase
and GF
Phase
CB2 only
CB1
S1
Phase fault on system
S2
control
logic
72
Phase Protection
Gen 1
Utility
> 1000 A
> 150 VLN
Trip!
Phase
CB2 only
CB1
S1
1.
Phase fault on system
2.
B1 trips on phase overcurrent, ATS
loses S1, Gen 1 starts
S2
control
logic
73
Phase Protection
Gen 1
Utility
> 1000 A
> 150 VLN
Trip!
Phase
and GF
Phase fault on system
2.
B1 trips on phase overcurrent, ATS
loses S1, Gen 1 starts
3.
Transfers load to Gen 1.
Phase
CB2 only
CB1
S1
1.
S2
control
logic
74
Phase Protection
Gen 1
Utility
> 1000 A
> 150 VLN
Trip!
Phase
and GF
Phase fault on system
2.
B1 trips on phase overcurrent, ATS
loses S1, Gen 1 starts
3.
Transfers load to Gen 1.
4.
S2 Trips! – No power to load
Phase
CB2 only
CB1
S1
1.
S2
control
logic
75
Phase Protection
Gen 1
Utility
> 1000 A
> 150 VLN
Trip!
Phase
and GF
Phase fault on system
2.
B1 trips on phase overcurrent, ATS
loses S1, Gen 1 starts
3.
Transfers load to Gen 1.
4.
S2 Trips! – No power to load
5.
Both B1 and B2 are tripped and locked
out, requiring manual reset. Facility in
dark.
Phase
CB2 only
CB1
S1
1.
S2
control
logic
76
Phase/Ground Discrimination



How would you design the system so you don’t
close the generator into a bolted fault?
… but allow the generator to close into a ground
fault…
How could this be done?
77
Phase and GF Discrimination
Gen 1
Utility
1.
Install Trip Units with separate phase and ground
trip outputs.
> 1000 A
> 150 VLN
Phase
only
Phase
and GF
CB1
S1
trip
unit
CB2
trip
unit
S2
Lockout
control
logic
78
Phase and GF Discrimination
Gen 1
Utility
> 1000 A
> 150 VLN
1.
Install Trip Units with separate phase and ground
trip outputs.
2.
Connect Phase trip to lockout input of ATS control.
Phase
only
Phase
and GF
CB1
S1
trip
unit
CB2
trip
unit
S2
Lockout
control
logic
79
Phase and GF Discrimination
Gen 1
Utility
> 1000 A
> 150 VLN
1.
Install Trip Units with separate phase and ground
trip outputs.
2.
Connect Phase trip to lockout input of ATS control.
Phase
CB1
S1
trip
unit
Ground
Phase
CB2
trip
unit
Ground
S2
Lockout
control
logic
or
80
Phase and GF Discrimination
Gen 1
Utility
> 1000 A
> 150 VLN
1.
Install Trip Units with separate phase and ground
trip outputs.
2.
Connect Phase trip to lockout input of ATS control.
3.
Phase
CB1
S1
trip
unit
Ground
B1 trips on phase overcurrent
Phase
CB2
trip
unit
Ground
S2
Lockout
control
logic
or
81
Phase and GF Discrimination
Gen 1
Utility
> 1000 A
> 150 VLN
1.
Install Trip Units with separate phase and ground
trip outputs.
2.
Connect Phase trip to lockout input of ATS control.
Phase
CB1
S1
trip
unit
Ground
Phase
CB2
trip
unit
Ground
3.
B1 trips on phase overcurrent
4.
Gen 1 does not start. Does not close
into fault. Saves wear and tear on
generator and transfer switch.
S2
Lockout
control
logic
or
82
Phase and GF Discrimination
Gen 1
Utility
> 1000 A
> 150 VLN
Phase
S1
CB1
trip
unit
Ground
1.
Install Trip Units with separate phase and ground
trip outputs.
2.
Connect Phase trip to lockout input of ATS control.
Phase
S2
CB2
trip
unit
Lockout
control
logic
Ground
or
3.
B1 trips on phase overcurrent
4.
Gen 1 does not start. Does not close
into fault. Saves wear and tear on
generator and transfer switch.
Incorporating the overcurrent within
the transfer switch achieves desired
result of not closing into phase fault
83
(Major Hospital), North Central US
21-SEP-02 …in the case of ------ Hospital's power failure,
which lasted an hour, a power line wound up
carrying more than its normal load for four days, which melted a fuse. That set off a chain of
events that wound up overloading the hospital's emergency generators, causing them
to fail, too. Mark Enger, the hospital's president, said the power failure could have been
life-threatening. The power dropped but didn't go out entirely. It dropped enough, however,
to trigger the hospital's three emergency generators. But because of the way the system is
wired, the generators' cooling fans failed to work, the generators overheated and the
hospital lost all power at about 11 a.m. Enger said there were eight surgeries going
when the power failed. Four of the surgeons were able to finish their operations, while the
other four finished quickly and re-scheduled the surgeries for the next day. Partial power
was restored by noon, and full power was restored the next day, Enger said. (The local
utility) is adamant that its maintenance practices are not posing widespread service
problems. But one (utility) worker said the hospital's power failure is but a symptom of the
electrical grid's ill health. (St. Paul MN, Pioneer Press 8-6-2003)
(Major) Hospital
On April 16, 2002, (---) Hospital lost power for an
afternoon, leaving various parts of the 33-building campus
dark for varying amounts of time. At (----) building, an
emergency generator immediately turned on, emergency
lights came on, and no essential services were disrupted,
according to a (local newspaper) article.
However, at (the --- main) Hospital, the backup electric system did not work, prompting
Mayor Vincent A. Cianci Jr., to tell the (local paper), “A hospital of this magnitude and this
size should not have these problems.” Surprisingly, power outages do happen with
alarming frequency to big hospitals. In fact, they’ve happened at (this) Hospital campus
before. In September 1999, a blackout plunged the entire campus into darkness. The
backup systems failed once again and this time a patient died after his respirator failed.
Then, in January 2000, another power failure forced the hospital to rely on backup
generators for nearly two hours and shut down nonessential equipment and lights. A faulty
ceramic insulator at a substation on the hospital campus caused the failure. Then a
damaged coil prevented some of the backup power from flowing back into one of the
hospital buildings. (EC&M Magazine 8-1-2002)
Would You Classify These Loads
As Critical or Essential?






Kitchen and dietary department?
Radiology and associated cooling?
Computer network (hubs, routers, servers)?
Computer room cooling for servers?
Fan and exhaust loads for biohazard containment?
Chillers, air handlers, BMS, dampers, AF drives for
patient and occupant comfort?
86
Would You Classify These Loads
As Critical or Essential?






Kitchen and dietary department?
Radiology and associated cooling?
Computer network (hubs, routers, servers)?
Computer room cooling for servers?
Fan and exhaust loads for biohazard containment?
Chillers, air handlers, BMS, dampers, AF drives for
patient and occupant comfort?
 Article 702 Optional Standby Loads ?
Background
Case Studies
Techniques
Coordination
ATS Designs
Withstand
PF and X/R
Tips / Summary
87
06-AUG-03 A power failure forced ------ Medical Center to shut
its emergency room and turn away visitors and some patients
yesterday, as the hospital staff struggled with limited use of the airconditioning, computers and other equipment. Chris Olert, a
spokesman for (local utility), said, "We know that it was a combined
failure of some of our equipment and some of the hospital's
equipment, but we don't know exactly what triggered it.“ He
said a cable feeding electricity to the medical center was damaged
and had to be bypassed. When the power failed, the hospital's
backup generators automatically turned on, but they
could not carry the entire load, so hospital officials shut down some functions to preserve
electricity for the most crucial ones. "No critical services were affected," said Lynn Odell, a
hospital spokeswoman. But hospital employees interviewed outside the building and family
members of some patients said things were seriously disrupted for a time.
One worker told of a darkened pharmacy with dormant computers, where pharmacists using
flashlights filled out paperwork by hand and responded to orders by telephone rather than
computer. Another spoke of a stiflingly hot surgery department where some medicines
spoiled in a nonworking refrigerator. (New York Times 8-6-2003)
2004 – Hurricane Charley

Power could not be restored to a regional
hospital in Charlotte County Florida for 4 days


Hospital only had 28 hours of fuel
Fastest way was add trailer supplemental power
•
Had to cut hole near inlet damper for cables
89
2004 – Hurricane Charley

Power could not be restored to a regional
hospital in Charlotte County Florida for 4 days


Hospital only had 28 hours of fuel
Fastest way was add trailer supplemental power
•
Had to cut hole near inlet damper for cables
90
Backup-Power Challenges




Background
Background
Backup power is required for Essential loads (Equipment
Systems & Emergency Systems) but not for all electrical
loads
Recent prolonged outages (blackouts, hurricanes, floods)
have raised the importance of backing up what used to
be thought of as non-essential loads
Why? Hospitals cannot perform normal activities when
those “non-essential” loads are not operational
Periodic connection of load bank may be necessary to
achieve sufficient generator loading (meet NFPA 99
guidelines for exhaust gas temperature)
Case
Case
Studies
Studies
Techniques
Techniques
Coordination
Coordination
ATSATS
Designs
Designs
Withstand
Withstand
PF PF
andand
X/RX/R
TipsTips
/ Summary
/ Summary
91
Spare Critical Power Generator
Gen 1
Utility
B1
Gen 2
Roll Up
Spare
B2
Normal Bus
Critical Bus
S1
S2
“Non-Essential”
Loads
ATS 1
S1
S2
ATS 2
Critical Loads
Critical Loads
92
Spare Critical Power Generator
Gen 1
Utility
B1
Gen 2
Roll Up
Spare
B2
Normal Bus
Critical Bus
S1
S2
“Non-Essential”
Loads
ATS 1
S1
S2
ATS 2
Critical Loads
Critical Loads
93
Spare Critical Power Generator
Gen 1
Utility
B1
Gen 2
Roll Up
Spare
How do I connect the generator
to the switchgear? Normal Bus
B2
Critical Bus
S1
S2
“Non-Essential”
Loads
ATS 1
S1
S2
ATS 2
Critical Loads
Critical Loads
94
It Takes A While….
To connect
from here…
… to here
… you must first bend
conduit, break walls, pull
and terminate cables…
95
Generator Quick Connect
Switchboard Characteristics

Engineered Assembly designed for safe & fast connection of a
mobile generator

Based on Cutler-Hammer Pow-R-Line switchboard construction

Indoor or Outdoor Enclosure

Generator Service disconnect circuit breaker rated up to 4000 amps

Cam-type plugs commonly found on mobile generator cables

Standard mechanical lugs provided for an alternative method of
connecting generator cables
96
Spare Critical Power Generator
Gen 1
Utility
B1
Gen 2
Roll Up
Spare
B2
Normal Bus
Critical Bus
S1
S2
“Non-Essential”
Loads
ATS 1
S1
S2
ATS 2
Critical Loads
Critical Loads
97
Spare Critical Power Generator
Gen 1
Utility
Roll Up
Spare
Gen 2
Multiple
Hubbell
400A
Plugs
B1
1. Install Quick Connect Panel
Quick
Connect (QC)
Panel
B2
Normal Bus
Critical Bus
S1
S2
“Non-Essential”
Loads
ATS 1
S1
S2
ATS 2
Critical Loads
Critical Loads
98
Spare Critical Power Generator
Gen 1
Utility
1. Install Quick Connect Panel
Gen 2
2. Bring generator to site
Quick
Connect (QC)
Panel
B1
B2
Normal Bus
Critical Bus
S1
S2
“Non-Essential”
Loads
ATS 1
S1
S2
ATS 2
Critical Loads
Critical Loads
99
Spare Critical Power Generator
Gen 1
Utility
1. Install Quick Connect Panel
Gen 2
2. Bring generator to site
3. Connect plug-in cables to
generator
4. Connect other end of cables to
QC panel
Quick
Connect (QC)
Panel
B1
B2
Normal Bus
Critical Bus
S1
S2
“Non-Essential”
Loads
ATS 1
S1
S2
ATS 2
Critical Loads
Critical Loads
100
Spare Critical Power Generator
Gen 1
Utility
1. Install Quick Connect Panel
Gen 2
2. Bring generator to site
3. Connect plug-in cables to
generator
4. Connect other end of cables to
QC panel
Quick
Connect (QC)
Panel
B1
B2
5. Start generator
6. Close QC panel tie breaker
QC tie
breaker
Normal Bus
Critical Bus
S1
S2
“Non-Essential”
Loads
ATS 1
S1
S2
ATS 2
Critical Loads
Critical Loads
101
Quick Connect Panel
102
Would You Classify These Loads
As Critical or Essential?






Kitchen and dietary department?
Radiology and associated cooling?
Computer network (hubs, routers, servers)?
Computer room cooling for servers?
Fan and exhaust loads for biohazard containment?
Chillers, air handlers, BMS, dampers, AF drives for
patient and occupant comfort?
 Article 702 Optional Standby Loads ?

Also consider

Rural versus city center – historical reliability
103
Roll Up Backup to Non-Essential
Loads
Gen 1
Utility
B1
Gen 2
Roll Up
Spare
B2
Normal Bus
Critical Bus
S1
S2
“Non-Essential”
Loads
ATS 1
S1
S2
ATS 2
Critical Loads
Critical Loads
104
Roll Up Backup to Non-Essential
Loads
Gen 1
Utility
B1
Gen 2
Roll Up
Spare
B2
Normal Bus
Critical Bus
S1
S2
“Non-Essential”
Loads
ATS 1
S1
S2
ATS 2
Critical Loads
Critical Loads
105
Roll Up Backup to Non-Essential
Loads
Gen 1
Utility
Gen 2
K
Roll Up
Spare
K
B1
B2
Normal Bus
Critical Bus
S1
S2
“Non-Essential”
Loads
ATS 1
S1
S2
ATS 2
Critical Loads
Critical Loads
106
Roll Up Backup to Non-Essential
Loads
Gen 1
Utility
Gen 2
K
Roll Up
Spare
K
B1
B2
Normal Bus
Critical Bus
S1
S2
“Non-Essential”
Loads
ATS 1
S1
S2
ATS 2
Critical Loads
Critical Loads
107
Roll Up Backup to Non-Essential
Loads
Gen 1
Utility
Gen 2
Roll Up
Spare
Quick
Connect (QC)
Panel
K
K
B1
B2
Normal Bus
Critical Bus
S1
S2
“Non-Essential”
Loads
ATS 1
S1
S2
ATS 2
Critical Loads
Critical Loads
108
Roll Up Backup to Non-Essential
Loads
Gen 1
Utility
Gen 2
Roll Up
Spare
Roll Up
Spare
Quick
Connect (QC)
Panel
K
Quick
Connect (QC)
Panel
K
B1
K
B2
Normal Bus
Critical Bus
S1
S2
“Non-Essential”
Loads
ATS 1
S1
S2
ATS 2
Critical Loads
Critical Loads
109
Roll Up Backup to Non-Essential
Loads
Gen 1
Utility
Gen 2
Roll Up
Spare
Roll Up
Spare
Quick
Connect (QC)
Panel
K
Quick
Connect (QC)
Panel
K
B1
K
B2
Normal Bus
Critical Bus
S1
S2
“Non-Essential”
Loads
ATS 1
S1
S2
ATS 2
Critical Loads
Critical Loads
110
What Other Generator Problems
Might Occur?

JCAHO allows operating generators at less than
30% load, but they state that these generators
must be “exercised annually with supplemental
loads of:



25 percent of nameplate rating for 30 minutes,
followed by
50 percent of nameplate rating for 30 minutes,
followed by
75 percent of nameplate rating for 60 minutes for a
total of two continuous hours.”
111
“Supplemental Load”



One method is to connect a “load
bank” to generators too boost load
Load banks can be permanently mounted, but
most sites just rent them from their engine dealer
when needed
Of course, rental units have to be connected to
the hospital generator system safely:

“How do I connect a temporary load bank to my
generator bank (without propping open a door or
window to bring in cables and letting rodents, wasps,
snakes etc, in?)”
112
Supplemental Load
Gen 1
Utility
Gen 2
Quick
Connect (QC)
Panel
B1
B2
QC tie
breaker
Normal Bus
Critical Bus
S1
S2
“Non-Essential”
Loads
ATS 1
S1
S2
ATS 2
Critical Loads
Critical Loads
113
Supplemental Load and Additional
Generation
Gen 1
Utility
Gen 2
Quick
Connect (QC)
Panel
B1
B2
Quick
Connect (QC)
Panel
QC tie
breaker
QC tie
breaker
Normal Bus
Critical Bus
S1
S2
“Non-Essential”
Loads
ATS 1
S1
S2
ATS 2
Critical Loads
Critical Loads
114
Presentation Complete


Questions?
At conclusion of Q/A, those interested in CEU
credit, we will next present a two question test.



Correct answer is either A,B,C or D
Submit these answers with your information requested
in the reminder e-mail sent to each person
If you are interested in CEUs but did not get the
answer and instruction sheet, send an email to me:
[email protected]
115
Question 1

Bus within switchboards built to the UL891
standard must be built to withstand a short
circuit current for what duration and still survive
with no damage?
A. 1 cycle (0.01667 seconds)
B. 3 cycle (0.05 seconds)
C. 4 cycle (0.0667 seconds)
D. 30 cycle (0.5 second)
116
Question 2: What must be the ATS
short-time rating?
G
Utility
4000 A
PCB
1600 A
PCB
4000 A PCB (Static Trip – LS)
Frame:
4000(Static
A, Sensor:
4000
A PCB
Trip 4000
– LS)
LTPU: 4000
0.8 A, Sensor:
LTD: 2.0
sec.
Frame:
4000
STPU: 0.8
2.0
STD: 2.0
0.4 sec.
sec.
LTPU:
LTD:
No Instantaneous
Trip 0.4 sec.
STPU:
2.0
STD:
No Instantaneous Trip
1600 A PCB (Static Trip – LS)
Frame:
1600(Static
A, Sensor:
1600
A PCB
Trip 1600
– LS)
LTPU:
1.0
LTD:
4.0
sec.
Frame: 1600 A, Sensor: 1600
STPU: 1.0
2.0
STD: 4.0
0.2sec.
sec.
LTPU:
LTD:
No Instantaneous
Trip 0.2 sec.
STPU:
2.0
STD:
1600 A
PCB
1600 A ATS
800 A
PCB
600 A
MCB
No Instantaneous Trip
800 A PCB (Static Trip – LS)
Frame:
800(Static
A, Sensor:
800
A PCB
Trip 800
– LS)
LTPU:
1.0
LTD:(0.05
7.0
A. 3800
cycles
Frame:
A, Sensor:
800sec.s)
STPU: 1.0
3.0
STD: 7.0
0.1 sec.
sec.
LTPU:
LTD:
No
Trip(0.1
B.Instantaneous
63.0cycles
s)
STPU:
STD:
0.1 sec.
No Instantaneous Trip
C. A MCB
12 cycles
s) LI)
600
(Thermal -(0.2
Magnetic,
Frame:
600 (Thermal
A, Trip: -600
A
600
A MCB
Magnetic,
LI)
D.
24
cycles
(0.4
s)
Instantaneous
5*T=3000
Frame:
600 A,PU:
Trip:
600 A A
117
Fax, E-mail, Submit on Web or Mail
Answers

Include the other data requested (address, SS#,
etc.) on answer form

FAX: 412-893-2137

Email: [email protected]

Web: www.pps2.com/r1

Mail:
Eaton Corporation
1000 Cherrington Parkway
Moon Township, PA 15108
Att: Dave Loucks (412-893-3300)
118
CEU Credits


You can review your credits on-line and print a
transcript from
https://www.acenet.edu/transcripts/
Results are posted no later than 6 weeks after
submittal of forms
119
The End
Copy of Powerpoint presentation, webinar
replay and FAQ will be posted to:
www.pps2.com/r1/i.htm
Questions: [email protected]
© 2005 Eaton Corporation. All rights reserved.