Transcript intropqseminar

Power Quality, Reliability
and Management
What is a Power Quality Problem?
“Any occurrence manifested in voltage,
current, or frequency deviations that
results in failure or mis-operation of
end-use equipment.”
What does that mean?
It’s dependant on your susceptibility.
Given the quality of supply do I have to
worry about problems with my equipment
or systems?
Typical Financial Loss Per Event
Industry
Typical Loss
Financial
$6,000,000/event
Semi-conductor mfg.
$3,800,000/event
Computer operations
$750,000/event
Telecommunications
$30,000/minute
Data processing
$10,000/minute
Steel/heavy mfg.
$300,000/event
Plastics
$10,000-15,000/event
Source: The Cost of Power Quality, Copper Development Association, March, 2001
Sources Of Power Problems
Referenced at the utility PCC (point of common coupling)
• Utility
• lightning, PF correction caps, faults, switching
• impact from other customers
• Internal to the facility
•
•
•
•
individual load characteristics, motors, ASDs
computers, microprocessors
wiring
changing loads
Typically, 70% of all PQ events
are generated within the facility
Types Of Power Quality Disturbances
(per IEEE 1159)
•Transients
•RMS Variations
•Short Duration Variations
•Long Duration Variations
•Sustained
•Waveform Distortion
•DC Offset
•Harmonics
•Interharmonics
•Notching
•Voltage Fluctuations
•Power Frequency Variations
Types of Power Quality Problems
Voltage
Swells
29%
Transients
8%
Interruptions
3%
Voltage
Sags
60%
What is a Transient?
Momentary (& undesirable) high frequency subcycle “event”
• Usually measured in microseconds
• May also be called a Spike, Surge or Impulse
• Characteristics of a Transient:
• Rise time (dv/dt)
• Ring frequency
• Point-on-wave
• Multiple zero crossings
• Magnitude
Transients
Unipolar
Positive
Bipolar
Notching
Oscillatory
200
100
0
-100
-200
Negative
Multiple Zero Crossings
A transient power quality event has occurred on DataNode H09_5530. The
event occurred at 10-16-2001 05:03:36 on phase A. Characteristics were
Mag = 478.V (1.22pu), Max Deviation (Peak-to-Peak) = 271.V (0.69pu),
Dur = 0.006 s (0.35 cyc.), Frequency = 1,568. Hz, Category = 3 Upstream
Capacitor Switching
Transients
Possible Causes
• PF cap energization

Possible Effects
• Data corruption
• Lightning
• Equipment damage
• Loose connection
• Data transmission errors
• Load or source switching
• Intermittent equipment operation
• RF burst
• Reduced equipment life
• Irreproducible problems
What is an RMS Variation?
(longer duration events)
A change in the RMS voltage. Typically 16 ms
(1 cycle) or longer
• Reduction in voltage: Sag or Interruption
• Increase in voltage: Swell
RMS Voltage Variations
Sag
100
0
-100
Swell
Interruption
Motor Starting
Timeplot Chart
Volts
Amps
222.5
900
CHA Vrms
CHA Irms
800
220.0
700
217.5
600
215.0
500
400
212.5
300
210.0
200
207.5
100
205.0
09:49:00.5
09:49:01.0
09:49:01.5
09:49:02.0
CHA Vrms
09:49:02.5
CHA Irms
09/13/96 09:49:00.50 - 09/13/96 09:49:04.00
09:49:03.0
09:49:03.5
0
09:49:04.0
Min
206.11
1.40
Max Median
222.25 219.19
847.71 207.16
IEEE1159 Characterizations
(RMS Variations)
• Instantaneous (0.5 - 30 cycles)
• Sag (0.1 - 0.9 pu)
• Swell (1.1 - 1.8 pu)
• Momentary (30 cycles - 3 sec)
• Interruption (< 0.1 pu, 0.5 cycles - 3s)
• Sag
• Swell
• Temporary (3 sec - 1 minute)
• Long Duration (beyond 1 minute)
What is Directivity?
Where the problem originated referenced to the point being
monitored (where the instrument is)
• Typically referred to as “Upstream” or “Downstream”
• Upstream
• Source side. Originated from the source of supply (can be utility)
• Downstream
• Load side. Originated from a load
• Helps you identify where the problem is and what actions to
take.
Case Study – Major Financial Institution
(Benefits of Learning Directivity)
•
•
•
•
Problem – Utility Sag
Damaged elevator controls
No UPS alarms (2 static, 1 rotary)
No reported problems with critical systems
02/19/2002
00:29:29.26
PM Module
Input
Temporary
Sag
Rms Voltage
AB
Mag = 366.V (0.76pu), Dur = 3.300 s, Category = 2,
Upstream Sag
02/19/2002
00:29:29.26
SYSA Input
Temporary
Sag
Rms Voltage
AB
Mag = 353.V (0.73pu), Dur = 3.300 s, Category = 2,
Upstream Sag
02/19/2002
00:29:29.26
SYSB Input
Temporary
Sag
Rms Voltage
AB
Mag = 372.V (0.78pu), Dur = 3.300 s, Category = 2,
Upstream Sag
Utility Sag
Utility Supply RMS Trend
Utility Supply Waveforms
Corresponding UPS Swell
Utility Supply
UPS Swell
UPS Output
Conclusion
• Utility sags damaged elevator controls
• Corresponding UPS Swell coincident with utility
return to normal
• Cause of swell being investigated by manufacturer
• Possible effects of swells”
• Damaged power supplies and other devices
Without monitoring, the customer would
be unaware of the UPS problem. The next
time, the damage could be worse
PQ Rule #1
For a source generated Sag, the current
usually decreases or goes to zero
August 14, 2003 Blackout:
Long Duration Interruption
PQ Rule #2
For a load generated Sag, the current
usually increases significantly.
Waveforms
Vo lts
A m ps
400
150 0
300
100 0
200
500
100
0
0
-50 0
-10 0
-10 00
-20 0
-15 00
-30 0
-40 0
09:49:00 .90
09:49:00 .95
09:49:01.00
C H A Vo lts
09:49:01.04
C H A A m ps
Pre/Post-trigger at 09/13/1996 09:49:00.947
File: C:\DranView \K_DEMO pq+ with inrush data.dnv
-20 00
09:49:01.09
RMS Voltage Variations
Causes and Effects
Possible Causes
• Sudden change in load current

Possible Effects
• Process interruption
• Fault on feeder
• Data loss
• Fault on parallel feeder
• Data transmission errors
• Motor start
• PLC or computer misoperation
• Undersized distribution system
• Damaged product
• Motor failure
Common RMS Voltage Variations
Visualization methods using power monitoring
instrumentation
•Sampled
data
•Recorded
Waveforms
•Magnitude
vs. Time
•Timelines
•Magnitude
vs. Event Duration
•CBEMA (IEEE
•ITIC
•3-D Mag-Dur
•Equipment
•Custom
446)
susceptibility curves
curves that represent that specific device
IEEE 446 - 1995 Limits (CBEMA)
Information Technology Industry Council
(ITIC) Curve
Another Perspective – 3D Mag-Dur Histogram
Case Study
(Laser
Printer Heating Cycle)
Voltage Timeline
Vl-n= 120 --> 108
45 seconds
SAG when heater turns on
V l-n
I load
Overlay Voltage & Current - Heater turning on
What is a harmonic?
An integer multiple of the fundamental
frequency
Fundamental (1st harmonic) = 60hz
2nd = 120hz
3rd = 180hz
4th = 240hz
5th = 300hz
…
Linear Voltage / Current
No Harmonic Content
voltage
current
Non-Linear Voltage / Current
Harmonic Content
voltage
current
When should I be concerned about Harmonics?
 Harmonics are typically considered a problem when they are
always present…Steady state distortion that is continuously
occurring.
 Although any waveform can have harmonics we are typically
concerned with the cumulative effects of continual harmonic
distortion on the power system
Waveforms
A m ps
200
15 0
10 0
50
0
-50
- 10 0
- 15 0
14 :3 4 :4 2 . 2 0
14 :3 4 :4 2 . 2 1
14 :3 4 :4 2 . 2 2
14 :3 4 :4 2 . 2 3
14 :3 4 :4 2 . 2 4
CH A
14 :3 4 :4 2 . 2 5
A m ps
Waveform event at 03/22/1999 14:34:42.480
File: C:\ DranView \Q_D EMO Cycle by cycle harmonics.dnv
14 :3 4 :4 2 . 2 6
-20 0
14 :3 4 :4 2 . 2 7
How are harmonics measured?
 Individual Harmonics
 2, 3, 4, 5, 6…50+
 Fourier Transform, FFT, DFT
 Total Harmonic Distortion (THD)
 Ratio, expressed as % of sum of all harmonics to:
 Fundamental (THD)
 Total RMS
 Load Current (I TDD only)
 Interharmonics
 Content between integer harmonics
 Required for new IEC standards (IEC 61000-4-30)
Harmonic Spectrum
Event waveform/detail
% o f FND
12.5
10.0
7.5
5.0
2.5
0.0
Thd
H05
H10
H15
H20
CH A Vo lts
T otal RMS: 24882.56 Volts
DC Lev el : 880.46 Volts
Fundamental(H1) RMS: 24725.89 Volts
T otal Harmonic Distortion (H02-H50):
10.60 % of FND
Ev en contribution (H02-H50):
7.97 % of FND
Odd contribution (H03-H49):
6.99 % of FND
H25
H30
PQ Rule #3
Even harmonics typically do not appear in a properly
operating power system.
Symmetry
 Positive & Negative halves the same: Only odd harmonics.
 If they are different: Even & Odd harmonics
What are Triplen Harmonics?
Harmonics who’s order is a multiple of 3
 3, 6, 9, …
Why should I be concerned about
Triplen Harmonics?
• Triplen Harmonics add in the neutral.
Additive Triplen Harmonics
Harmonics (sustained)
Possible Causes
• Rectified inputs of
power supplies
• Non-symmetrical current
• Intermittent electrical noise
from loose connections

Possible Effects
• Overload of neutral conductors
• Overload of power sources
• Low power factor
• Reduced ride-through
Case Study
(Laser Printer Heating Cycle)
Continued…
Current Waveform - heater on
HARMONIC DISTORTION - heater on
Harmonics V l-n Vthd = 2.8%
Harmonics I load Ithd = 5%
Current With Printer Idle
Harmonic Distortion - Idle
Harmonics V l-n
Vthd = 3.1%
Harmonics I load Ithd = 140%
Review of What We Just Saw

Nearly Sinusoidal Current
–

Voltage and Current In-phase
–

Low Voltage Harmonic Distortion (4%)
Power Factor Near One
Flat-topping of Voltage when Idle

Corresponds with Current Pulse
Other PQ Concerns
(defined in IEEE 1159)
• Frequency
• Frequency different from the ideal 50/60hz
• Frequency not synchronized with the grid
• Unbalance
• Deviation from the average 3 phase voltage (IEEE)
• Voltage Fluctuations (Flicker)
• Small changes to the magnitude of the voltage
• Visual perception. Effects on lights
How Many Can You Find?
Monitoring Approaches
and Tools
 Handheld/Portable
 (Reactive) Vs. Permanently
Installed (Proactive)
Reactive Monitoring




After the fact - Reactive
Forensic approach
Problem Solving, Hopefully you’ll find it!
Portable instrumentation typically used
Proactive Monitoring

Permanently installed monitoring systems

Anticipate the future, On-Line when trouble occurs

Monitor system dynamics

Preventive Maintenance, Trending, identify
equipment deterioration

Power Quality and Flow
Monitoring Solutions From
Dranetz-BMI
Portable/Handheld
Permanently Installed
Get the right tool for the job!
Handheld Family
Capabilities
New Products!
PowerXplorer PX5
PowerGuide 4400
PowerGuide 4400
• 8 Channels
• 4 Differential Voltage, AC/DC
• 4 Current, AC/DC
• 256 Samples Per Cycle
• 50/60HZ, 16/20HZ (railroad)
• Harmonics to the 63rd
• Flicker
• Low Freq Transients (up to 5KHZ)
• Medium Freq Transients (510KHZ)
• Ethernet, USB, serial commun.
Unique annunciator
Color touch screen
PowerGuide 4400
• Applications
• Inrush
• Fault Recorder
• Motor Testing
• Power Studies
• System Commissioning/compatibility
• Telecommunications
• General Troubleshooting
• Compliance
PowerXplorer PX-5
• Advanced Power Quality Analysis
• Includes all PowerGuide 4400 Features
• High Speed (658/8800 like) Digitized
Transients
• Advanced Power Analysis
• IEEE1459
• PX5-400 – 400HZ Option
PowerXplorer PX-5
• Applications
• All PowerGuide 4400 Plus…
• Medical Diagnostic Equipment
• Advanced PQ Surveys
• 400HZ Aircraft, Naval, Military
• Utility Surveys
• Any 658 or 8800 application
Advanced Visualization
Data to ...
... Information to ...
... Answers
Thank You!
Questions?
Dranetz-BMI
1000 New Durham Rd.
Edison, NJ 08818
1800-372-6832
www.dranetz-bmi.com