Transcript Power Measurement

Fluke LPQI 2007
1
Fluke Corporation
European Headquarters
Eindhoven, the Netherlands
Corporate Headquarters
near Seattle, WA, USA
Fluke LPQI 2007
2
Fluke Corporation
• Founded in basement of John Fluke’s
home in Springdale, Connecticut, USA
in 1948
• 2,400 employees worldwide
• Offices in 21 countries around the world
• Distributed in more than 100 countries
• Manufacturing facilities in Everett (USA),
the Netherlands, the U.K. and China
Fluke LPQI 2007
3
Measurements for Power
Quality maintenance
Fluke PDM seminar Module 1
4
Industry trends
1) Growing concern for personal safety
-
complexity of today’s systems, bring over voltage risks
international & national regulations (& guidance)
2) Increased attention on power related issues
-
deregulation of power distribution
Increasing loads on power systems
3) Shift from reactive maintenance to preventive
maintenance
– More work by fewer people
– Decreasing maintenance budget
– More complex equipment
Fluke LPQI 2007
5
History of Maintenance Practices
• 20 years ago…
Tool use by application*
TREND
Scheduled
Predictive
•Thermal Imaging
•Ultrasonic testing
•Vibration Analyzers
•Recorders/Loggers
•Motor/Circuit Test
•Oil Testers
Preventive
•PQ Analyzers
•IR Temperature
•Insulation testers
Reactive
Fluke LPQI 2007
•Network Test
•Scope Meters
•Loop Cal.
•Clamp Meter
•DMM
•Simple
Testers
– The primary goal of
maintenance was loss
prevention and the fundamental
requirement was to provide the
basic need at minimum cost.
• Today…
– Companies are researching all
possible means to extend the
productive life
6
Types of Maintenance
Break-down
Reactive
Maintenance
Cost
Repair it when it fails
Preventive
Maintenance
Cost
Time
Maintenance at regular
intervals
Predictive
Maintenance
Cost
Time
Problem detected before
predicted failure.
Maintenance planned
ahead
Time
Fluke LPQI 2007
7
Power Quality
• Effects of bad power quality are not immediately obvious
• Bad power quality can come from anywhere
• Consequences could be severe (production loss)
• Power quality problems are a root cause:
–
–
–
–
Malfunction
Shutdown
Excessive energy cost
Decreased lifetime of equipment
Fluke LPQI 2007
8
Example
Fluke PDM seminar Module 1
9
Example
• This manufacturer is the third biggest power consumer of the local
energy supplier. They produce fiber materials for sports equipment.
• A new heating system was installed on a key process
• During a routine check with a thermographic camera it was
discovered there had been an increase in temperature of the neutral
conductor.
• Check with a current clamp revealed 20A Phase currents & 40A
Neutral current
Fluke LPQI 2007
10
Example
• A power quality logger was used to gather the
needed data.
• Connection was only possible on the
distribution board connection, fused with 250A,
not at the heater due to safety reasons.
• This makes analysis a bit more complex since
the heater represents a small part of the total
load
Fluke LPQI 2007
11
Results
Current trend
Neutral current
Question: Why does the neutral carry 60A and not only 6A which would be the
difference between currents in L1, L2 and L3?
Fluke LPQI 2007
12
Results 2
• Conclusion; there is a
third harmonic
present in the neutral
Fluke LPQI 2007
13
Conclusion
Further analysis showed that:
10A fund
35A 3rd
• The reason for the neutral conductor overload clearly is the heating
installation, which generates high triplen harmonics
• More unbalances present so further more measurements would be
very helpful.
What was the cause?
• Regulators built into the heating system require harmonic filters which
were not installed
Fluke LPQI 2007
14
Conclusion
• Thermal survey gives early warning of a problem
• Addition of new equipment can introduce problems which
are not obvious or visible
• Performing system check “before” and “after” can prevent
future failures
• “Balanced” loads still can have harmonic content running
in the neutral
Fluke LPQI 2007
15
Measurement of Electrical Systems
Fluke PDM seminar Module 1
16
Measurement
1. Safety
2. Power Quality Measurement




The effect of distortion on simple test tools
Measurement of Harmonics
Measurement Specifications
Typical measurements
3. Power Quality Measurement Equipment
 Basic Measurements
 Test equipment types
Fluke LPQI 2007
17
Measurement
1. Safety
2. Power Quality Measurement




The effect of distortion on simple test tools
Measurement of Harmonics
Measurement Specifications
Typical measurements
3. Power Quality Measurement Equipment
 Basic Measurements
 Test equipment types
Fluke LPQI 2007
18
Safety of Measurement
• Example
– DMM fitted with low energy fuse used incorrectly on
a high energy circuit
Fluke LPQI 2007
19
EN61010 LV Directive
Implemented in 1998
All instruments have to be tested by an
independent test house (2004)
Each instrument must be marked with an
Overvoltage Category ( CAT I, II, III, IV )
As well as a voltage level (300, 600, 1000 Volts)
Fluke LPQI 2007
20
Category Rating
• CAT IV - Electricity meters and primary connection
• CAT III - Permanent connection to the fixed installation.
• CAT II - Appliances, portable tools etc.
• CAT I - Protected electronic circuits.
Fluke LPQI 2007
21
Voltage Rating per Category
Test Impulse Rating
Voltage Phase-Zero
CAT I
CAT II
CAT III
300
1500
2500
4000
600
2500
4000
6000
1000
4000
6000
8000
Source Impedance
30 Ω
12 Ω
2Ω
Fluke LPQI 2007
CAT IV
8000
2Ω
22
IEC 1010 / EN61010
• Regulations are not an option
• Second edition EN61010 ( 2004 ) requires
independent testing
• Remember Test leads are CAT rated ...
Fluke LPQI 2007
23
Available from Fluke
•
•
•
•
Free Safety DVD
Not sales focused
Information on EN61010
Interview with an arc blast
survivor
Fluke LPQI 2007
24
Measurement Seminar
1. Safety
2. Power Quality Measurement




The effect of distortion on simple test tools
Measurement of Harmonics
Measurement Specifications
Typical measurements
3. Power Quality Measurement Equipment
 Basic Measurements
 Test equipment types
Fluke LPQI 2007
25
Harmonics
Distorted waveforms
Harmonic frequencies combine with the fundamental sine
wave to form non-sinusoidal (distorted) waveforms.
1
3
sin(x)
0.8*sin(3*x+3.6)
0.5*sin(5*x+0.6)
0.22*sin(7*x+3.8)
0.8
0.6
sin(x)+0.8*sin(3*x+3.6)+0.5*sin( 5*x+0.6) +0.22*s in(7*x+3.8)
2
0.4
1
0.2
=
0
-0.2
-0.4
-0.6
0
-1
-2
-0.8
-1
-3
0
1
Fluke LPQI 2007
2
3
t [msec]
4
5
6
0
1
2
3
t [msec]
4
5
26
6
Effect of distortion on test tools
Fluke PDM seminar Module 1
27
Measurement Methods
• Both Clamp Meter’s are calibrated and functioning correctly
59.2 A AC
Fluke LPQI 2007
40.5 A AC
28
Measurement
Sinewave
• How does a measurement device measure the
effective value of a waveform ?
• Two Methods - Averaging & True RMS
Fluke LPQI 2007
29
Averaging Measurement
• Effective (RMS) value = 1.11 X Average value.
Fluke LPQI 2007
30
Non-linear Loads
Switching Power Supply
Volts
Amps
• What happens to the measurement device if the waveform is
distorted by non-linear loads ?
Fluke LPQI 2007
31
Measurement
Distorted Waveform
• Effective (RMS) value = 1.85 x Average value.
• An averaging measurement device (1.11 x) would
read up to 40 % too low.
RMS
AVG
Fluke LPQI 2007
32
Nuisance tripping at 60A ?
True RMS Measurement
Averaging Measurement
59.2 A AC
40.5 A AC
Fluke LPQI 2007
33
True RMS Measurement
True RMS / Harmonics
• A True RMS meter calculates the effective
heating value of the distorted waveform
• This will include all harmonics
Fluke LPQI 2007
34
Crest Factor
• Peak value = 1.414 X RMS value.
• 1.414 = Crest Factor.
Fluke LPQI 2007
35
Crest Factor
Distorted Waveform
• Peak value = 2.9 X RMS Value.
• 2.9 = Crest Factor.
Pea
k
RMS
Fluke LPQI 2007
36
Crest Factor
Distorted Waveforms
C.F. = 1.43
C.F. = 2.39
C.F. = 4.68
• Professional Multimeters usually rated at CF <3
• High Quality units rated at CF of 6
• Power Quality Analyzer CF >11
Fluke LPQI 2007
37
Power Measurement
Two Power Factors

Screen Shots from a Fluke 43 Single Phase and a Fluke 434 Three Phase analyser
Fluke LPQI 2007
38
Power Measurement
• System with no Harmonic content
Reactive power (kVAr)
Apparent power (kVA)
True Power (W)
Cos φ (dpf) = true power (fundamental)
Fluke LPQI 2007
39
Power Measurement
• System with Harmonic content
Reactive power (kVAr)
Apparent power including
harmonics (kVA)
True Power (W)
Reactive power
(Harmonic component)
Cos φ (dpf) : true power/Reactive power (fundamental)
PF: true power/reactive power (incl harmonics)
Fluke LPQI 2007
40
Power Measurement
Two Power Factors !

Screen Shots from a Fluke 43 Single Phase and a Fluke 434 Three Phase analyser
Fluke LPQI 2007
41
Measurement where Harmonics are
present
1. Always use True RMS
2. Check the crest factor rating
3. When measuring power be aware of PF vs Cos φ/(DPF)
C.F. = 1.43
Fluke LPQI 2007
C.F. = 2.39
C.F. = 4.68
42
2) Measurement of Harmonics
Fluke PDM seminar Module 1
43
EN50160 Harmonics
Upper limits for individual harmonic voltages at the supply terminals in % of
nominal voltage. 95% of 10-minute average Vrms over 1 week must be below
limits
Odd harmonics
Even Harmonics
Not multiples of 3
Multiples of 3
Order
h
Relative voltage
Order
h
Relative voltage
Order
h
Relative voltage
5
6%
3
5%
2
2%
7
5%
9
1.5 %
4
1%
11
3.5 %
15
0.5 %
6…24
0.5 %
13
3%
21
0.5 %
17
2%
19
1.5 %
23
1.5 %
25
1.5 %
VIRTUALLY ALL HARMONIC PROBLEMS ARE GENERATED
“IN HOUSE”
Fluke LPQI 2007
44
IEC 61000-4-30 specification
Test Equipment
Class B
Class A
Measurement
Interval
Accuracy
Hz
10 sec
± 10mHz
Manufacturer to indicate
Magnitude supply voltage
Vrms
10 cycles
± 0.1%
Manufacturer to indicate
Flicker (IEC 61000-4-15)
Plt
2 hr
± 5%
Manufacturer to indicate
Voltage dips, swells and
interruptions, rapid voltage
changes
½ cycle Vrms
10 ms
± 0.2%
½ cycle Vrms
Unbalance (method of
symmetrical components)
Vrms fundamental
10 cycles
± 0.15%
(uncert.)
Manufacturer to indicate
THD, Harm V, A,
Inter harmonics
10 cycles
± 1-5%
Manufacturer to indicate
V peak
50 μ sec
(200KS/s)
Inter harmonic
10 cycles
± 1-5%
Manufacturer to indicate
Power frequency
Harmonics (IEC 61000-4-7)
Transients (not specified)
Mains signaling
Flagging
Dip, swells, interruptions might create unreliable
readings of Hz, Vrms, Unbalance and Harm.
Therefore Must be re flagged (dirty) to avoid miss
interpretation
Not specified
Time synchronization
External clock;
GPS
Manufacturer to indicate
Fluke LPQI 2007
1 period
45
Harmonic Measurement
• For troubleshooting
– Check the harmonics present
– Check for the levels of the harmonics
– Look for recognizable patterns
50 Hz
Fluke LPQI 2007
100 Hz
150 Hz
200 Hz
46
Harmonic Measurement – PC
Load
V, A, Hz Measurement
Fluke LPQI 2007
Harmonic Measurement
3rd Harmonic Content
47
Harmonic Measurement
Desktop System
Compact Fluorescent Lamp with HF Ballast
0.6000
0.0600
0.5000
0.0500
0.4000
Current (A)
Current (A)
0.0400
0.3000
0.2000
0.0300
0.0200
0.1000
0.0100
0.0000
0.0000
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
1
2
3
4
5
6
Harmonic
7
8
9
10
11
12
13
14
15
16
17
Harmonic
PC / IT Load
Elec. Fluorescent Lighting Ballast
Twelve pulse bridge - harmonic current
Six pulse bridge - harmonic current
25
25
20
20
15
15
%
%
10
10
5
5
0
1
2
3
4
5
6
7
8
9
10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25
Harmonic number
0
1
2
3
4
5
6
7
8
9
10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25
Harmonic number
6 Pulse Bridge
Fluke LPQI 2007
12 Pulse Bridge
48
Measurement Seminar
1. Safety
2. Power Quality Measurement




The effect of distortion on simple test tools
Measurement of Harmonics
Measurement Specifications
Typical measurements
3. Power Quality Measurement Equipment
 Basic Measurements
 Test equipment types
Fluke LPQI 2007
49
Types of Measurement Tools
1. Power Quality Troubleshooting / Survey tools
– Devices designed as a measurement tool
– Simple to use / Immediate measurements
– Troubleshooting / Survey tool / some logging
2. Power Quality “Logging”
– Devices designed for long term monitoring
– Record every parameter for detailed analysis
– Predictive Maintenance
Fluke LPQI 2007
50
Power Quality
Troubleshooting & Surveys
•
Measurements
1.
2.
3.
4.
5.
6.
7.
8.
9.
Volts Amps & Frequency
Power
Harmonics
Dips & Swells
Transients
Unbalance
Flicker
Inrush
Temperature
Fluke LPQI 2007
51
1) Volts, Amps & Frequency
• Using a Power Quality
Analyser
• View all of the main
parameters at point of
connection
• Graphical as well as
numeric display can help
highlight potential
problems
Scope
Vector
Trend
Fluke LPQI 2007
52
2) Power Measurement
• Typical power measurement
information
• Shows the sides of the
triangle
Fluke LPQI 2007
53
3) Three Phase Harmonic Measurement
Fluke LPQI 2007
54
4) Transient Measurement
• Cause….. interference
• Difficult to capture
– Triggering of ‘scopes difficult…width, timing, peak value ?
• Modern power quality analyzers purpose built for the job
• Envelope trigger
• Accurate real time stamping is essential
+X%
240V
- X%
Fluke LPQI 2007
55
5) Dips and Swells
• Recording of upstream and downstream sags can indicate
loads causing problems
Upstream Sag
Fluke LPQI 2007
Downstream Sag
56
6) Unbalance
• The phase diagram gives a quick
indication of phase relationships
and balance
• In this example voltage
unbalance is very small, but
current unbalance is nearly 19%.
Fluke LPQI 2007
57
7) Flicker Measurements
• A reading greater than 1 means that
most people will perceive flicker in an
incandescent bulb
• Measurement
– Pst (1 min): Short-term flicker over 1
minute
– Pst: Short-term flicker over 10 minutes
– Plt: Long-term flicker over 2 hours
Fluke LPQI 2007
58
8) Inrush
• Inrush Current Measurement
– Momentary peak of current
during switch on.
– Current clamps can capture
peak reading
– Analyzers can give time
measurement
Screen Shot of a PQA showing start-up
current generated by a cooling system
Three Phase Inrush Measurement
Fluke LPQI 2007
59
9) Temperature
• Many power quality problems initially result in an
increase in temperature of components,
connectors, cables and machinery
• Infra red non contact measurement is the ideal
way to locate this type of problem
Fluke LPQI 2007
60
Why infrared non-contact
measurement?
1) Measurement from distance
• Dangerous to contact (Electrical)
• Difficult to reach
• Moving objects
2) Measurement without contact
• Very hot objects
• Where contact would damage,
contaminate or change temperature
(Food & Chemical)
Fluke LPQI 2007
61
Example Substations
Fluke LPQI 2007
62
Substations
Both qualitative and
quantitative inspections are
Required to determine a fault
Fluke LPQI 2007
63
Electrical connections
The connections on this evaporator pump
read over 50 degrees hotter on phase 3
Fluke LPQI 2007
64
Electrical connections
• The temperature readouts show
that connection on the centre
phase of this main lighting
disconnect are hot, suggesting
an unbalanced load
Fluke LPQI 2007
65
Electrical connections
Fluke LPQI 2007
66
Electrical unbalance or overload?
Fluke LPQI 2007
67
Electrical unbalance or overload?
• Where is the increased
resistance? On the left
or on the right
contact?
• A hot spot is not
necessarily a faulty
connection!
Fluke LPQI 2007
68
Fluke Power Quality
Fluke PDM seminar Module 1
69
Single Phase Troubleshooting
Fluke 345 Power Clamp
Fluke LPQI 2007
Fluke 43B Analyzer
70
Three Phase Troubleshooting
Fluke 435 Power Quality
Troubleshooter
Fluke LPQI 2007
Fluke 1735 Power Logger
71
Power Quality Logging
Fluke 1740 Series Power
Quality Logger
Fluke LPQI 2007
Fluke 1760 Power Quality
Logger
72
Thermal Imaging
FlukeTi20 Thermal
Imaging Camera
Fluke LPQI 2007
FlukeTi40 & Ti50
Advanced Camera’s
73
More information
• Fluke Power Quality Data available in the exhibition
area
• DVD’s
– Thermal Imaging Application DVD
– Safety DVD – EN61010
– Power Quality Measurement DVD
• Fluke Website
– www.fluke.co.uk
• Short term requirement ?
Fluke LPQI 2007
74
Fluke PDM seminar Module 1
75