Hioki 3196 User manual

Case Studies of
Power Quality Surveys
using
Model 3196 Power Quality Analyzer
HIOKI E.E. CORPORATION
July 2005
Rev. 5

TABLE OF CONTENTS
Power Quality Basics: Current Power Supply Environment Page 1
Power Quality Standards Page 1
Main Power Quality Parameters Page 2 to 4
Case Study 1: Inrush Current and Current RMS Value of a Dryer Page 5 to 6
Case Study 2:
Switching of Power Factor Improvement
Capacitor
Page 7 to 8
Case Study 3:
Voltage Dip (Instantaneous Voltage Drop
- at Receptacle
Page 9 to 10
Case Study 4:
Voltage Dip (Instantaneous Voltage Drop)
- at Distribution Panel
Page 11
Case Study 5:
Transient Overvoltage
Page 12 to 13
Case Study 6:
Periodical Instantaneous Voltage Drop
Page 14
Case Study 7:
General UPS Switching Waveform
Page 15
Case Study 8: Page 16
Case Study 9: Page 17
Case Study 10: Voltage Waveform Noise & UPS Switching Page 18 to 19
Appendix: Power Quality Survey Procedures Page 27 to 28
Case Study 11:
Case Study 12:
Voltage Dip in a Factory
Inflow and Outflow of Harmonics
Voltage Drop Caused by Wiring Impedance
Transients Caused by Glow Fluorescent Lighting
Page 20 to 22
Page 23 to 26

- page 1 -
Power Quality Basics
Current Power Supply Environment
Power Quality Standards
Various factors can contribute to worsening power quality
International
Power Quality
Deterioration
Open market
Tough competition to
cut costs
Increase use of PCs
and inverter devices
Connection with new
energy sources (wind,
solar, gas turbine, etc.)
Connection with on-
site power supply
Connection
mixes the
different
power
characteristics
Europe
U.S.A.
Standard Title Published Comment
IEC
61000-4-7
IEC
61000-4-15
IEC
61000-4-30
EN50160
IEEE 1159
IEEE 519
IEEE 446
ANSI C84.1
General guide on harmonics and inter-
harmonics measurements and
instrumentation, for power supply systems
and equipment connected thereto
1991
2002 revised
Actualization of inter-
harmonic concept (from
revision)
Flicker meter - Functional and design
specifications
Testing and measurement techniques
Power Quality measurement methods
1997
2003 A1
2003
120V/60Hz added in
amendment
New standard
Standard Title Published Comment
Standard Title Published Comment
Voltage Characteristics of electricity
supplied by public distribution systems
1995,
1999 revised
General power quality
standard
IEEE Recommended Practice for
Monitoring Electric Power Quality
IEEE Recommended Practice and
Requirements
IEEE Recommended Practice for
Emergency and Standby Power Systems
for Industrial and Commercial Applications
Electrical Power Systems and Equipment -
Voltage Ratings (60Hz)
1995
1992
1995
1995
Anomaly voltage
Classification of basic
terms
Standards for harmonic
limit values
Describes the CBEMA
curve
Voltage limit values

- page 2 -
ITIC (CBEMA) curve
The ITIC curve judges the allowable level of
voltage RMS fluctuation from the voltage swell,
voltage dip and interruption events.
The analysis is made by the period and depth of
each event according to the limit value of the ITIC
curve.
The ITIC (Information Technology Industry
Council) curve is the most recent version of the
older CBEMA (Computer and Business
Equipment Manufacturers Association) curve.
Both were created by CBEMA. The original
CBEMA curve was widely used in the U.S.A.
Main Power Quality Parameters
1. Transient overvoltage (impulse)
1) Phenomenon
Radical changes in voltage with high voltage
peaks
2) Cause
3) Damage
4) Analysis
Lightning strikes
Power circuit switching
Closure of inductive circuits
Arc to the ground
Load switching
Contact of a bouncing relay
Destruction of power supplies of
equipment
Equipment reset
Waveform (Maximum voltage level, Rise
time, Phase angle, Fluctuation,
Repeatability)
The faster rise time means a closer
occurring point.
2. Voltage Dip
1) Phenomenon
Instantaneous drop of RMS voltage
2) Cause
3) Damage
Large inrush current by turning on heavy
loads
Accident in the distribution network
(Lightning, snow, ice, contact of birds/
trees, effects of accidents)
Short-circuit
Stop or equipment reset

- page 3 -
3. Voltage Swell
1) Phenomenon
Instantaneous rise of RMS voltage
2) Cause
3) Damage
Lightning strikes
Introducing heavy loads
Destruction of power supplies in
equipment
4. Instantaneous Interruptions
1) Phenomenon
Instantaneous or short/long term power
outage
2) Cause
3) Damage
Accident on distribution network
(Lightning, snow, ice, contact of birds/
trees, effects of accidents)
Short-circuit
Stop or equipment reset
5. Unbalance Factor
1) Phenomenon
Imbalance of each phase in 3-phase system
2) Cause
3) Damage
Imbalance of loads by 1-phase load
connection (especially long distribution
lines)
Transformer capacity difference at
receptacle
Overheating of a 3-phase inductive motor
or transformer
Stop equipment by 3E relay tripping (over-
current, missing phase, reverse-phase)
Uneven motor rotation

6. Harmonics
1) Phenomenon
Voltage or current waveform distortion
2) Cause
3) Damage
Thyristor powered conversion devices
Inverter, Variable frequency drives
Overheating, burning, abnormal sounds or
vibration sound caused by the inflow of
harmonic current to the equipment
Malfunctions due to the harmonics voltage
(overheating or burning of reactor for
phase advancing capacitor)
7. Flicker
1) Phenomenon
Regularly repeated voltage impulses spanning
one or more cycles which cause flicker in the
lighting device
2) Cause
3) Damage
Arc/blast furnaces
Arc welding
Flicker in the lighting device
Equipment malfunction
- page 4 -

- page 5 -
CASE STUDY 1
Inrush Current and Current RMS Value of an Industrial Dryer
Environment:
Problem:
Analysis:
Target: 1-phase 2-wire, 100V circuit
This is a simple simulation example.
By using an industrial dryer (100V
AC, 1kW, 50/60Hz), the RMS
fluctuation and inrush current are
measured while switching the dryer
from "OFF=>ON=>COLD=>OFF."
Note:
Model 9694 Clamp on Sensor is
clamped to the 10-turn coil with a CT
setting 0.1.
To record the inrush current event waveform, use the current peak event.
To record the waveform while the dryer is continuously operating in HOT, using themanual event
([ESC]+[EVENT]) is effective.
Current RMS Value Fluctuation
OFF HOT HOTCOLD
The current value while a dryer is working is
10Arms, but the start-up current rises to
10.951Arms.

- page 6 -
Fluctuation of Current Waveform Peak (+) Fluctuation of Current Waveform Peak (-)
Fluctuation of Voltage RMS Value Fluctuation of Active Power RMS Value
A voltage drop of about 4Vrms is measured when the dryer is in operation.
The maximum power is 1.1071kW
Inrush Current Waveform

- page 7 -
CASE STUDY 2
Voltage Drop Caused by Wiring Impedance
Environment:
Problem:
Analysis:
Target: 1-phase 2-wire, 100V circuit
This is an easy simlulation similar to Case Study 1 to monitor the voltage drop caused by wiring
impedance. The voltage at a load shows the voltage drop to the supply side when the wire is thin
and long.
CH2
CH1
When switching an industrial dryer (100V
AC, 1kW, 50/60Hz) from OFF to HOT to
COLD and back to OFF, confirm the
difference in voltage drop between short
and long wirings.
1) When wiring is short
(low wiring impedance without the wires
circled in red)
2) When wiring is long
(high wiring impedance with wires circled in
red)
1) Short Wiring 2) Long Wiring
Voltage RMS Value Fluctuation
Voltage at power supply side
Voltage at consumption side
U1 (CH1: red) is the voltage not affected
by the wiring impedance.
U2 (CH2: green) is the voltage affected
by the wiring impedance.
By adding high wiring impedance, the
voltage drops for 6Vrms on the
consumption side.
The wiring impedance of the wires circled in
red is 0.6-Ohm.
The voltage drop is calculated by using the
Ohm's Law such that "0.6-Ohm x 10A =
6Vrms."
6Vrms

- page 8 -
1) Short Wiring 2) Long Wiring
Current RMS Value Fluctuation
1) Short Wiring 2) Long Wiring
Current Peak Value Fluctuation
In this dryer example, the current consumption at a load is slightly reduced when the wirng is long.
The dryer is a resistive load, so that the current consumption, which means the power consumption,
is reduced by the voltage drop.
If a constant power controlled load is connected, the power consumption is stable despite the
voltage drop. Therefore, the current consumption increases.
When HOT When HOT
When HOT When HOT

Transient peak value is accurately
measured using the 2MHz sampling
speed.
- page 9 -
CASE STUDY 3
Transients Caused by Glow Fluorescent Lighting
Environment:
Problem:
Analysis:
Target: 1-phase 2-wire, 100V circuit
This is an example of measuring transient overvoltage when turning on glow fluorescent lighting.
A glow fluorescent light incorporates a glow
lamp and is widely recognized as a low-cost
alternative to fluorescent lighting.
A fluorescent light needs to be warmed-up for
its electrodes to be switched on. A glow lamp
is provided for this purpose. It flashes to
warm-up the electrodes before the fluorescent
light is actually turned on.
Transient overvoltage is generated at the first
flash of a glow lamp, which affects electronic
equipment located nearby.
Glow lamp
Voltage and Transient Waveforms When Turning On the Fluorescent Light
Line of voltage=0 Cursor B
Cursor A

- page 10 -
The power is turned on at the voltage
waveform peak (128.9V) and the generated
transient overvoltage is 103.1V in the negative
direction.
Voltage and Current Waveforms When Turning On the Fluorescent Light
When transient overvoltage occurs, a high
current flows instantaneously.
This example is measured by using a 10-turn
coil without a CT ratio setting.
The screen shot on the left shows that
0.9602A of current flowed instantaneously to
the negative direction.

- page 11 -
CASE STUDY 4
Switching of Power Factor Correction Capacitor
Environment:
Problem:
Analysis:
Target: 1-phase 2-wire, 100V circuit
The power supply of equipment is damaged.
Some events are recorded by measurement.
The switching waveform, which occurs during the power factor correction capacitor switching, is
detected. This kind of voltage waveform is recorded when the power factor correction capacitor is
installed in a facility. The switching noise comes through the low-voltage circuit without a filtering
device.
Voltage Noise Waveform 1 (By the voltage waveform distortion event)
Also, a transient (impulse) voltage waveform is detected.
This kind of waveform occurs when the voltage waveform is affected by the start-up current of
equipment.
Voltage Noise Waveform 2 (By the voltage waveform distortion event)
To detect intermittent noise, the voltage waveform distortion event is effective. The voltage
waveform distortion event is set as the percentage of the voltage range. A setting from 10%to
15% is recommended.
Note:

- page 12 -
CASE STUDY 5
Voltage Dip (Instantaneous Voltage Drop) - at Receptacle
Environment:
Problem and Analysis:
Target: HIOKI headquarters building,
3-phase 4-wire, 6.6kV receptacle, Secondary side of PT
While measuring for 1 year at the receptacle of a 3-phase 6.6kV circuit, a voltage dip is detected
only during a lightning strike. This voltage dip occurred 6 times in 3 consecutive days (August5 to
7, 2003). The residual voltage is very low and a long period is detected on CH3 (T-R phase) as
4.708kV for 109ms.
1 year from June 2003 to May 2004Measured period:
Voltage Fluctuation
Classification in EN50160 mode
(Simultaneous events on 3 phases are counted asone.)
Voltage Dip Evaluation by ITIC Curve
(plotted for each phase separately)

- page 13 -
Event Voltage Fluctuation of the Lowest Residual Voltage and the Shortest Period Voltage Dip
The instantaneous high voltage is generated by a lightning strike and it shorts the distribution
cable and tower. Then, the fault current flows and the voltage drops.
To remove this fault, the circuit breaker takes effect , but the voltage drops until that time
(approx. 0.07 to 2s).
This is the instantaneous voltage drop (voltage dip) caused by a lightning strike.
Protective
relay
Transformer
Breaker
2. Problem on distribution
3. Problem on network
4. Instantaneous voltage drop
5. Malfunction of equipment
Path of a Voltage Dip
Protective
relay
Breaker

- page 14 -
CASE STUDY 6
Voltage Dip (Instantaneous Voltage Drop) - at Distribution Panel
Environment:
Problem and Analysis:
Target: HIOKI headquarters building, East side, 5th floor
3-phase 3-wire, 200V distribution panel
4 voltage dips caused by lightning were detected during measurement (different period than Case
Study 3). The distribution panel (1-phase 3-wire) was affected by the voltage dip that occurred at
the high voltage distribution network. The table below shows the residual voltage and period of
each voltage dip. Voltage dips caused by lightning are unpreventable by the power distribution
companies. Therefore, users should take appropriate countermeasures such as connectinga UPS
to their PCs.
From June 9, 2002 to August 9, 2002Measured period:
Residual Voltage Period
1st voltage dip
2nd voltage dip
3rd voltage dip
4th voltage dip
63Vrms
47Vrms
82Vrms
56Vrms
117ms
109ms
50ms
116ms
Event Voltage Fluctuation at the 2nd VoltageDip
Voltage and Current Waveforms at the 2nd Voltage Dip

- page 15 -
CASE STUDY 7
Transient Overvoltage
Environment:
Analysis:
Target: Factory, 3-phase 3-wire, 200V circuit
A transient overvoltage was detected in all events occurring several times duringthe
measurement. Unfortunately, the cause of the transient could not be determined.
Problem:
The screen of equipment does not correctly display.
Analysis of transient waveform
Occurred on all 3 phases (R-S, S-T, T-R) simultaneously.1)
Occurred twice in 1 cycle of the commercial waveform, and the interval between 2 events is
820µs.
2)
The level is between 120V to 260V peak-to-peak.3)
The frequency is between 10kHz and 30kHz.4)
The threshold set at 1/2 of the waveform peak value is effective for the transient overvoltage.
For example, set the threshold at 0.07kV for the 100Vrms circuit, and 0.14kV for the 200Vrms circuit.
Note:
Analysis of Transient Overvoltage
U1 U2 U3
Max. value
Min. value
Transient
p-p value
-116.0V
-329.3V
323.4V
153.5V
98.4V
-55.1V
213.3V 169.9V 153.5V

- page 16 -
CASE STUDY 8
Periodical Instantaneous Voltage Drop
Environment:
Analysis:
Target: Retail store, 1-phase 2-wire, 100V outlet
When analyzing the voltage RMS value fluctuation, the following two phenomena were observed.
(The graph shows measurement during 12 hours in the night for a period of 2 weeks.)
Problem:
No apparent trouble is detected, but the voltage fluctuation is big.
Maximum value: 106.70Vrms, Average value: 102.53Vrms, Minimum value: 93.25Vrms1)
Instantaneous voltage drop occurred every 13 minutes.2)
Voltage Fluctuation
The cause of the instantaneous voltage drop every 13 minutes is assumed to originate froman
electronic device connected to the line as this outlet is turned on or works periodically via a timer.
The device may have a high inrush current - common in equipment such as laser printers, copy
machines, electric heaters, etc. A laser printer consumes current periodically, and causes a
voltage drop as a result of its start-up current consumption. An electric heater also causes a
voltage drop from the periodic inrush current ON/OFF of the thermostat,
There are many instantaneous voltage drops, but the minimum voltage is 93.25Vrms which is
about 7% lower than the nominal voltage. Most equipment works normally at this voltage level.

- page 17 -
CASE STUDY 9
General UPS Switching Waveform
Environment:
Problem and Analysis:
Most low cost UPS used for general purposes output a square wave. However, most people
assume that a sine wave is output. Here is a sample waveform output by the UPS.
UPS for a desktop PCs sold in retail stores (1-phase 2-wire, 100V)
Low cost inverter (variable frequency drive) type1)
Commercial purpose without a compensation function for the voltage distortion, etc.2)
Note that the voltage swell or dip occurs in switching if the UPS does not compensate for the
period.
Event Voltage Fluctuation of UPS Output
Switching from
commercial
power supply to
UPS when the
power supply
drops.
Switching from
UPS to
commercial
power supply
when the power
supply recovers.
Voltage Waveform when the Power Supply Drops
(switching from commercial power sup ply to UPS)
Voltage Waveform when the Power Supply Recovers
(switching from UPS to commercial power supply)
Target:

- page 18 -
CASE STUDY 10
Voltage Waveform Noise & UPS Switching
Environment:
Analysis:
Target: 1-phase 2-wire, 100V power supply circuit
68 "Wave (voltage waveform distortion)" events were recorded during an 18-day measurement
period using the following settings on Model 3196. All events are of the same type.
Problem:
Malfunction of equipment
Event Settings of Model 3196
Event List