EFFECTS VOLTAGE SAG ON SINGLE-PHASE DOMESTIC AND OFFICE LOADS

Mahendra V Chilukuri, Lee Ming Yong and Phang Yoke Yin

Faculty of Engineering, Multimedia University, Cyberjaya 63100, Malaysia

Abstract: This paper presents the effects of voltage sags on domestic and office

equipment and provides equipment sensitive curves for safe and reliable operation based

on the experimental results. With the increase usage of sensitive electronic equipments in

various industries, offices and household appliances, it is important to protect them from

any power quality disturbances to avoid unnecessary losses of any kind. From the several

types of power quality disturbances, the most frequent and concern for electric utilities

from customer point of view was voltage sag. Though a lot of research has been done

voltage sag characteristics and its effects on industrial equipment there is not much

literature available on the effect of voltage sags on single-phase loads, especially office

and home equipment. This project investigates the behavior of domestic and office

appliances for different magnitude, duration and angle of incidence of voltage sag.

Studies were conducted to obtain the sag tolerance curves which might or might not

comply with the voltage sag immunity standards. Industrial power corruptor was used to

generate voltage sag on one phase to observe the effects on the test equipment.

Experiments were conducted on common office and household appliances using

Industrial Power Corruptor (IPC) to monitor the equipment function and performance

before, during and after the sag. The current and voltage waveforms obtained from the

IPC software were analyzed and reported. The results seem to be useful and informative

for OEMs, Utilities and Emergency Power Supply Manufacturers.

Index Terms—Power Quality, Voltage Sag, Industrial Power Corruptor, Power System Faults.

1 INTRODUCTION

Deregulation and privatization of electricity industry lead to the open competition to

provide electricity at higher reliability and quality then ever before to growing

automotive industry. The increased use of ICT and semiconductor devices at home and

1

offices has increased the challenges for utility and industry to focus on power quality.

Though there are many types of power quality disturbances arising in electric

transmission and distribution system some of them or more frequent than other. Voltage

sag is one of the major power quality problem faced by the customers and requires

solutions at utility and customer level along with some radical changes at design of

equipment. Voltage sag is defined as more than 10% reduction in rms voltage from 0.5

cycles to 1 minute. The IEC definition for this phenomenon is dip [1]. Many high-tech

electricity-dependent devices and equipment used in commercial and industrial facilities

are sensitive to many types of power quality disturbances. On the other hand, the

increasing use of power electronics devices contributes further to the arising power

quality problems.

1.1 Voltage Sag Standards

Standards are needed for the effects of voltage sags on sensitive electronic equipment as

reference documents describing single equipment or component and systems in power

system. Both buyers and manufacturers use these standards to meet better power

compatibility. Manufacturers refer to the standard to manufacture products complying

requirement of the standard and buyers demand from the manufacturers that the product

should comply with the standard. The most common standards dealing with power

quality are IEEE, IEC, CBEMA and SEMI. Brief description of each standard is provided

as following.

1.2 IEEE Standards

IEEE Standard P1346 - Electric Power System Compatibility with Electronic Process

Equipment. This standard contains indices that will allow industrial engineers to evaluate

how sensitive their industrial processes will be to voltage sags. In addition, “IEEE

Standard 446-1995 - Recommended practice for emergency and standby power systems

for industrial and commercial applications range of sensibility loads”, includes the

CBEMA curve to show the equipment susceptibility to voltage sags. Due to the increase

of sensitive equipments, the voltage sag limit in the CBEMA curve might not be

restrictive enough to protect some type of sensitive equipments. IEEE Standard 1159 -

Recommended Practice for Monitoring Electric Power Quality defines a sustained

interruption as reduction in the rms voltage to less than 10% of the nominal voltage for

2

longer than 1 minute. Sustained interruptions must be taken seriously as the fault will

cause disturbances and affect all the customers on the faulted section [8].

1.3 SEMI

The SEMI International Program is a service offered by Semiconductor Equipment and

Materials International (SEMI). It represents the semiconductor and flat panel display

equipment and materials industries with the goal of helping members expand global

marketing opportunities and improve customer access. The SEMI F47-0200 standard,

entitled “Specification for Semiconductor Processing Equipment Voltage Sag Immunity”

defines the desired voltage sag immunity for single and two-phase voltage sag events. It

only specifies voltage sags with duration from 50ms up to 1s. The specification states that

Semiconductor processing, metrology and automated test equipment must be designed

and built to conform to the voltage sag ride through capability per the defined curve in

the figure 1.1.

Figure 1.1 Required Semiconductor Equipment Voltage Sag Ride through Capability Curve (SEMI F47) [9]

1.4 Causes of Voltage Sag

The causes of voltage sag can be divided into two categories, depending on the location

of the source in relationship to the power meter. Faults can happen on the utility side of

the meter which includes switching operations, power system faults, regulator

dysfunction and lightning. While on the end user side of the meter, the faults include

nonlinear loads, poor grounding, electromagnetic interference and static electricity.

1.4.1 Utility side of the meter

3

Voltage sag caused by the utility side of the meter usually involve some type of activity

on the utility’s electrical power system either man made (switching operation) or natural

(lightning) events where both involve interruption of the voltage. Utilities switch

equipment on and off by the use of circuit breakers, disconnecting switches or reclosers.

Breaker trips when there is a fault on the power system or when breaker is due for

maintenance such as to insert capacitor for power factor improvement. As for natural

causes, lightning striking power line or substation equipment, tree or animal touching a

power line, car hitting a power pole, construction work may be cause of the faults. The

tripping of the breakers and the initiating fault will cause voltage to sag or swell

depending on the magnitude of the voltage and duration when it occurs. Faults on utility

side are usually categorized by single phase to ground faults, phase to phase faults or

three-phase to ground faults. The most common occurring faults is single phase to ground

and the possibility of three-phase fault occurring is very low.

1.4.2 End user side of the meter

Problems on the end user side of the meter usually happen when a disruption of

sinusoidal voltage and current is delivered to them by the utility. Faults also occur when

there’s excessive use of nonlinear load, starting of big motor which draws large amount

of current and causes voltage sag. These disturbances will affect the performance of

sensitive equipment but won’t damage them except for faults caused by transient that will

damage the equipments.

2 EXPERIMENTAL HARDWARE SETUP

2.1 Experimental Setup

In studying the effect of voltage sag on motor load domestic and IT-based equipment, a

voltage sag generator is required to initiate voltage sags. The voltage sags are generated

using the Industrial Power Corrupter (ITC) combined with a built in data acquisition

system. By using IPC, the user can control the depth and duration of voltage sags while

monitoring voltages, currents and other signals. Besides that, there were also 9 built in

standards in the IPC which are SEMI 47, CBEMA, ITIC, IEC 4-11, IEC 4-34, MIL1399,

Samsung, FAA1.3.2, FAA IPTE and F47 RQRD [11]. Among the 9 standards readily

available in the IPC, only 5 standards were used for testing in this study. SEMI 47 is an

industry standard for voltage sag immunity. Industrial equipment must tolerate voltage

4

sags on the AC mains supply to specific depths and duration. ITIC and CBEMA is used

for voltage sag immunity on computer, telecommunications, business equipments,

software and IT services. As for IEC 4-11 and IEC 4-34, both standards specify the same

depths and durations of voltage sags which test the toleration of equipments rated up to

16A and more than 16A per phase separately. The 3-phase supply from the utility is

connected to the IPC and from the IPC, the 3-phase output is connected to load as shown

in Figure 2.1. Three single phase socket for each phase is also fed by the IPC. True

phase-to-phase sags can be generated. It must be connected to a computer running the

IPC software and is controllable from the computer using graphical software that is based

on a Windows operating system. The main functions of the software are:

Figure 2.1 IPC connected to 3 phase power supply

1. Control the sag magnitude

2. Control the sag duration

3. Trigger a sag event

4. Download and display data that was acquired on selected channels during the sag

events for further analysis.

2.2 Test Procedure

The following are the test procedure followed to perform testing on motor, domestic and

IT-based loads to study the effect of voltage sags.

5

1. Define “Pass” and “Fail” for each equipment before conducting test

2. Connect the load to the 3 pin power supply socket

3. Select the suitable standard to be used for testing the equipments

4. Follow each pre-defined steps of the standards and trigger each sag event

5. Vary the sag duration and magnitude to find the threshold of the equipment where

it fails.

6. For each sag event triggered, voltage and current is recorded and the data can be

viewed using the Channel Scope software.

7. Plot a threshold vs. standard to compare whether the equipments tested complied

to the standard or not.

The recorded waveforms are analyzed and conclusions are derived based on the

waveforms and observations recorded.

2.3 Computation for Power Quality Parameters

The computation for some of the power quality parameters are explained as follows:

a) Voltage sag and swell detection:

Sag detection method used in this project was based on IEEE standard 1159 [1],

where RMS voltage below 0.9 p.u. of the system voltage is considered as voltage sag.

The sag duration was calculated from the time either one of the phases dropped below

the minimum voltage limit until all of the three phases recovered within voltage limit.

6

Figure 2.2 Type of fault observed from TNB PQMS data.

Figure 2.3 The occurrence of fault for 1 year from Jun 2005 – July 2006 at one PQ monitoring site (UKM, Bangi).

3 Experimental Results

The main purpose of conducting experiments on various equipments is to study the

effects of voltage sags on their operation and determine voltage tolerance curve for

equipment. For this experiment, the equipments are divided into the following categories:

a) Industrial equipment: 3 phase induction motor, VSD

b) Domestic equipment: electric kettle, electric oven, automatic rice cooker, television,

lightings, decoder, massager, fan, microwave oven, blender and UPS.

c) IT equipment: Hub, inkjet printer, laser printer, LCD monitor, scanner, computer and

CRO

The voltage sag magnitude and duration based on the pre-determined steps in each

standard had been investigated. As mentioned in the chapter No, the sags were generated

using IPC. The sag thresholds where the equipments fail were also determined by

adjusting sag magnitude and duration on the front panel of IPC.

7

3.1 Experiments on PC

Voltage sag doesn’t show any significant problem to personal computers. In such case, it

is easy to prevent the problem by installing uninterruptible power supply (UPS) for a

small cost which will provide sufficient time to save all the data before shutting down.

However it is not the same especially for PC-based offices which rely entirely on data

processing through PC in their work. An interruption will cause great losses; some

examples are financial trading and telecommunication offices.

a) Computer A

Intel Pentium II Processor

128MB RAM

4GB Hard Disk

Windows 98 OS

Cursor: -1ms -65.46 Volts www.PowerStandards.com

-500

-300

-100

100

300

500

Volts

L1-N load - milliseconds - 8/25/2006 3:30:50 PM

-40

-12

16

44

72

100

128

156

184

212

240

Cursor: -1ms . Amps www.PowerStandards.com

-20

-12

-4

4

12

20

Amps

L1 Ld (±1000A) - milliseconds - 8/25/2006 3:30:50 PM

-40

-12

16

44

72

100

128

156

184

212

240

Figure 3.1(a) Corresponding current and voltage of computer during voltage sag period

for 70% depth and 10-cycle duration, computer didn’t restart due to sag.

8

Cursor: 6.5ms 119.69 Volts www.PowerStandards.com

-500

-300

-100

100

300

500

Volts

L1-N load - milliseconds - 8/25/2006 3:41:28 PM-40 28 96 164 232 300 368 436 504 572 640

Cursor: 1.5ms .15 Amps www.PowerStandards.com

-50

-30

-10

10

30

50

Amps

L1 Ld (±100A) - milliseconds - 8/25/2006 3:41:28 PM-40 28 96 164 232 300 368 436 504 572 640

Figure 3.2(b) Corresponding current and voltage waveform of computer during voltage

sag period for 40% depth and 30-cycle duration, computer restarts due to sag.

Figure 5.3(a) shows the current and voltage waveform when computer A is running and

during the application of sag. Its load current before sag value is 2.5A. The restart of

computer A is marked by high current surge of 9 times the normal current, which is

indicated at the end of sag which can be seen in figure 5.3(b), for sag depth 40% and

duration of 30 cycles. It is observed that the value of current surge at the end of the sag is

higher compared to the case which computer A is not affected by sags. The value of the

spike is 22A in figure 5.3(b) when the computer restarts as compare to 14A in figure

5.3(a) when there is no effect of sag on the computer.

3.2 Computer B

Pentium (R) 4

504 MB RAM

80GB Hard Disk

Windows XP OS

Figure 5.4(a) shows the current and voltage waveform when computer B is running and

when sag is applied. Its load current before sag value is 1.5A. Computer B restarts at a

sag depth of 15% and 18-cycle duration. It is observed that there is a current surge at the

end of the sag when computer B restarts and no current surge in figure 5.4(b) when

computer B is not affected to sag. The value of the spike is 15A in figure 5.4(b) when the

computer restarts as compare to 5.5A in figure 5.4(a) when there is no effect of sag on

computer B.

9

Cursor: -1ms -34.2 Volts www.PowerStandards.com

-500

-300

-100

100

300

500

Volts

L3-N load - milliseconds - 3/28/2007 2:44:44 PM

-40

-30

-20

-10

0

10

20

30

40

50

60

Cursor: -1ms .49 Amps www.PowerStandards.com

-10

-6

-2

2

6

10

Amps

L3 Ld (±1000A) - milliseconds - 3/28/2007 2:44:44 PM

-40

-30

-20

-10

0

10

20

30

40

50

60

Figure 5.4(a) Corresponding current and voltage waveform of computer during voltage

sag period for 70% depth and 1-cycle duration, computer didn’t restart due to sag.

Cursor: -1ms -96.24 Volts www.PowerStandards.com

-500

-300

-100

100

300

500

Volts

L3-N load - milliseconds - 3/28/2007 2:57:27 PM

-40

4

48

92

136

180

224

268

312

356

400

Cursor: -1ms . Amps www.PowerStandards.com

-20

-12

-4

4

12

20Am

ps

L3 Ld (±1000A) - milliseconds - 3/28/2007 2:57:27 PM

-40

4

48

92

136

180

224

268

312

356

400

Figure 5.4(b) Corresponding current and voltage waveform of computer during voltage

sag period for 15% depth and 18-cycle duration, computer restart due to sag

Voltage sag can cause computers to restart and lose data. If the depth of voltage sag is larger than 40% and duration is more than 5 cycles for computer A, it will restart. Computer B will restart if the depth of sag is larger than 15% and a duration of more that 18-cycles. Voltage sag has no effect on computer for voltage sag and duration before the indicated value. From the experiment, it can be concluded that the specification of the computer plays an important role on the sag effect. It is shown that the latest model of the computer has higher ride through capability of voltage sag than the later model. Both computers comply with the voltage sag immunity standards. Similar experiments were conducted and on various domestic an office appliances and the following sag immunity table were obtained to analyze the behavior and function of the equipment.

TABLE 1: EFFECT OF VOLTAGE SAG ON THE RESTARTING OF COMPUTER A COMPARISON

Sag Depth

(%)

Sag Duration (in cycles)

5 10 20 30 40 60

10

70 N N N N N N

60 N N N N N N

50 N N N N N N

40 N Y Y Y Y Y

N: Computer does not restart due to sag

Y: Computer restarts due to sag

TABLE 2: EFFECT OF VOLTAGE SAG ON THE RESTARTING OF COMPUTER B

Sag Depth (%)

Sag Duration (in cycles)

5 10 20 30 40 60

25 N N N N N N

20 N N N N N N

15 N N Y Y Y Y

10 N N Y Y Y Y

N: Computer does not restart due to sag

Y: Computer restarts due to sag

TABLE 3: EFFECT OF VOLTAGE SAG ON THE PRINTER A

Sag

Depth

(%)

Sag Duration (in cycles)

5 10 20 30 40 60

30 N N N N N N

20 N N N N N N

10 N N N N N N

11

0 N Y Y Y Y Y

N: Printer doesn’t switch off due to sag

Y: Printer switches off due to sag

TABLE 4: EFFECT OF VOLTAGE SAG ON THE PRINTER B

Sag

Depth

(%)

Sag Duration (in cycles)

5 10 20 30 40 60

25 N N N N N N

20 N N N N N N

15 N N Y Y Y Y

10 N N Y Y Y Y

N: Printer doesn’t switch off due to sag

Y: Printer switches off due to sag

TABLE 5: EFFECT OF VOLTAGE SAG ON THE NETWORK HUB

Sag

Depth

(%)

Sag Duration (in cycles)

5 10 20 30 40 60

30 N N N N N N

20 N N N N N N

10 N N N N N Y

12

0 Y Y Y Y Y Y

N: Hub doesn’t switch off due to sag

Y: Hub switches off due to sag

TABLE 6: EFFECT OF VOLTAGE SAG ON LCD MONITOR

Sag

Depth

(%)

Sag Duration (in cycles)

5 10 20 30 40 60

25 N N N N N N

20 N N N N N N

15 N N Y Y Y Y

10 N N Y Y Y Y

N: LCD monitor doesn’t switch off due to sag

Y: LCD monitor switches off due to sag

TABLE 7: EFFECT OF VOLTAGE SAG ON THE SCANNER

Sag

Depth

(%)

Sag Duration (in cycles)

5 10 20 30 40 60

25 N N N N N N

20 N N N N N N

15 N N N N N N

13

10 N N Y Y Y Y

N: No effect on scanner due to sag

Y: Scanner stops operating and operation had to be restarted

TABLE 8: EFFECT OF VOLTAGE SAG ON L INCANDESCENT LAMP

Depth

(%)

Sag Duration (in cycles)

5 10 20 30 40 60

40 N N N N N N

30 N N N N N N

20 N N Y Y Y Y

10 N N Y Y Y Y

N: No effect on lamp due to sag

Y: Lamp switches off due to sag

TABLE 9: EFFECT OF VOLTAGE SAG ON ELECTRIC RICE COOKER

Sag

Depth

(%)

Sag Duration (in cycles)

5 10 20 30 40 60

50 N N N N N N

40 N N N N N N

30 N N N N N N

14

20 N Y Y Y Y Y

N: No effect on rice cooker due to sag

Y: Rice cooker switches off due to sag

TABLE 10: EFFECT OF VOLTAGE SAG ON TELEVISION

Sag

Depth

(%)

Sag Duration (in cycles)

5 10 20 30 40 60

40 N N N N N N

30 N N N N N N

20 N N N N N N

10 N N Y Y Y Y

N: No effect on television due to sag

Y: Television switches off due to sag

TABLE 11: EFFECT OF VOLTAGE SAG ON MICROWAVE

Depth

(%)

Duration (in cycles)

5 10 20 30 40 60

45 N N N N N N

40 N N N N N N

35 N Y Y Y Y Y

15

30 N Y Y Y Y Y

N: No effect on microwave due to sag

Y: Microwave switches off and operation had to be restarted due to sag

TABLE 12: EFFECT OF VOLTAGE SAG ON ASTRO DECODER

Depth

(%)

Duration (in cycles)

5 10 20 30 40 60

30 N N N N N N

20 N N N N N N

10 N N Y Y Y Y

0 N N Y Y Y Y

N: No effect on decoder due to sag

Y: Decoder switches off due to sag

TABLE 13: EFFECT OF VOLTAGE SAG ON MASSAGER

Depth

(%)

Duration (in cycles)

5 10 20 30 40 60

30 N N N N N N

20 N N N N Y Y

10 N N N N Y Y

16

0 N N N N Y Y

N: No effect on massager due to sag

Y: Massager stops operating and operation had to be restarted due to sag

4. Conclusion

Voltage sags are one of the most frequently occurring important power quality problems

in the industry process which can cost billions of production losses annually and the cost

is rising every year. It is important for the utilities and customers to understand the

effects of low power quality. This problem needs to be solved due to the increased use of

power quality-sensitive equipments, the increased use of equipments that generate power

quality problems, the increased interconnectedness of the power system and the

deregulation of the power industry. Recent hike in the electricity tariff increase by the

TNB, Malaysian government makes mandatory reason for the utilities & IPPs to improve

the power quality to residential & industrial customers and also manufacturers to design

equipment with sufficient immunity for power quality disturbances in order to satisfy the

customers and reduce damage [24].

1) From the data provided by TNB, the type of sag that occurs most is single stage dip

due to fault. This type of sag commonly affects residential areas as they are supplied

by single phase supply. As for industrial areas which are supplied by three phase

supply, the impact of sag on three phase motors is less severe if the fault is single

phase to ground fault. Tripping of motor might be avoided but operation of the

process might be affected as motor may decrease in speed and heat up; the life span

of the motor itself may decreases in the long run.

2) The experiment on equipments is divided into three categories; motor loads tested

against SEMI F47 standard, domestic loads tested against ICE 4-11 standard and IT

equipments tested against ITIC and CBEMA standards.

3) The conclusion of voltage sag on lightings and resistive loads by observing all the

waveforms are, during sag period the current is proportional to the sag voltage as the

load is resistive. Once the sag is over, the current returns to its normal value without a

current spike. There is no severe effect of sag on all the resistive equipments tested

but sag might shorten the life span of the equipments on a long haul.

17

4) The conclusion that can be made on non linear and IT equipments by observing the

waveforms are, when sag is applied there is a current surge at the end of sag when

voltage is about to be restored to its nominal value. This high current surge will trip

the protection in the equipment and cause the equipment to switch off, this is shown

through the waveform obtained from the experiment and through physical

observation. Some of the equipments may continue its operation when voltage is

restored and those equipments that had to be restarted will pose a problem for the

user.

5) There are a few factors to be considered to find the most efficient solution to the

voltage sag; the occurrence of sag, the sensitivity of the equipment, the place to install

the protection, the type of protection and cost. Installation of power conditioning

equipment helps reduce or eliminate power quality disturbances.

This project gives a more detail insight of the importance of voltage sag and how it will

affect industrial, office and home appliances. Household appliances do not get damaged

due to voltage sag and this has been observed from experimental results on domestic

appliances. This information is important as the usage of sensitive equipment is

increasing in all the areas and the effect of voltage sag would be a nuisance and unwanted

losses in time and money can be avoided. However, it is recommended to repeat the

performed experiment every few years to keep abreast with the latest technology

especially IT and non linear equipments which are more susceptible to sag.

5 Acknowledgment

The authors gratefully acknowledge the technical support of Faculty Lab Staff.

6 References

1. Institute of Electrical and Electronics Engineers, IEEE Std 1159-1995, IEEE Recommended Practice for Monitoring Electric Power Quality, USA, 1995, pp.11 – 25.

2. C. Radhakrishna, M. Eshwardas, Gokul Chebiyam “Impact of Voltage Sags in Practical Power System Networks”, Transmission and Distribution Conference and Exposition, 2001 IEEE/PES, Volume: 1, pp567-572, 28 Oct – 2 Nov 2001.

3. N.Abu Bakar, A. Mohaned, M. Ismail “A Case Study of Voltage Sag Analysis in a Utility Distribution System”, 2003.

18

4. E.Randolph Collins, Jr, Arshad Mansoor, “Effects of Voltage Sags on AC Motor Drives”, 1997.

5. Richard P. Bingham, “Sags and Swells” February 16, 1998. 6. George G Karady, “Effects of Voltage Sags on Loads in a Distribution System”,

October 2005.7. Math H.J. Bollen, “Understanding Power Quality Problems Voltage sags and

Interruptions”, 2000. 8. IEEE Std. 1159-1995, Recommended Practice on Monitoring Electric Power Quality,

Working Group on Monitoring Electrical Power Quality of SCC22- Power Quality, Draft 6, November, 1994.

9. http://www.pqview.com/graphics/semi.png [2006 , June 20]10. ITI (CBEMA) Curve. http://www.sea.siemens.com/step/templates/lesson.mason?

bsp:2:2:3 [2006, June 20]11. http://www.powerstandards.com/IPCSpecs.htm [2006, June 22]12. J.C. Das, “Effects of momentary voltage sags on the operation of induction and

synchronous motors,” IEEE Trans. Ind. Application, v.26, 1990, pp. 711-718. 13. PQWeb 3.1 Report Selection.

http://www.powermonitoring.com/pqwebdemo/query.asp [2006, July 8]14. Mark McGranaghan, Dave Mueller, “Effects Of Voltage Sags In Process Industry

Applications. [Online] 15. http://www.dranetz-bmi.com/pdf/processIndustryApplications.pdf [2006, June 18]16. Toshiba Lamp Catalogue17. http://en.wikipedia.org/wiki/Halogen_lamp#The_halogen_lamp18. Emmanouil Styvaktakis, Math H. J. Bollen and Irene Y. H. Gu, “Expert System for

Classification and Analysis of Power System Events”, IEEE Transactions on Power Delivery, Vol. 17, No. 2, April 2002.

19. Laporan Prestasi Perkhidmatan Pembekalan Elektrik Di Malaysia Edisi Tahun 200620. Mark McGranaghan, EPRI Solutions, “Dealing with Voltage Sags in Your Facility”,

Feb, 2006.21. Tosak Thasananutariya, Somchai Chatratana, Mark McGranaghan, “Economic

Evaluation of Solution Alternatives for Voltage Sags and Momentary Interruptions”, Electrical Power Quality and Utilisation, Magazine Vol. 1, No. 2, 2005.

22. Pacific Gas and Electric Company (June 2000). “Short Duration Voltage Sags can Cause Disruptions” [Online]. http://www.pge.com/docs/pdfs/biz/power_quality/power_quality_notes/voltagesags.pdf [2006, July 5].

23. Voltage-Dip Proofing Inverters & Voltage-Dip Compensators Booklet24. Pacific Gas and Electric Company, “Voltage Sag Ride-through Mitigation in

Sequence by Increasing Cost”, December 1999.25. Daily Express News (2006, May 25). “Power tariff hike in line with overall price

trend” [Online].http://feeds.kualalumpurnews.net/?rid=106c07de33d0249f&cat=48cba686fe041718&f=1 [2006, August 18].

26. Emmanouil Styvaktakis and Math H. J. Bollen, “Signatures of Voltage Dips: Transformer Saturation and Multistage

27. V. Gosbell, S. Perera, V. Smith, Voltage Sag Measurement and Characterization, Power Quality Centre Technical Note No. 4, Power Quality Centre, June 2001, pp. 8.

28. P. Parihar, E. Liu, Identification, Classification and Correlation of Monitored Power Quality Events, IEEE Power Engineering Society 1999 Winter Meeting, Vol. 1: 437-441, 1999

29. Ferrero and S. Salicone, An Easy VI Program to Detect Transient Disturbances in the Supply Voltage, IEEE Transactions on Instrumentation and Measurement, Vol. 54, No. 4: 1471 – 1474, 2005

19

30. M. Kubis, C. S .Choo. (No date) .Real-Time Monitoring and Analysis System for Power Quality. [Online]. National Instruments. http://sine.ni.com/csol/cds/item/vw/p/id/134/nid/124400[10 June 2006].

31. P. Daponte, M. Di Penta, Transient Meter: A Distributed Measurement System for Power Quality Monitoring, IEEE Transactions on Power Delivery, Vol. 19 No. 2: 456 - 463, April 2004.

32. L. Zhang and M. Bollen, A Method for Characterization of Three-Phase Unbalance Dips (Sags) from Recorded Voltage Waveshapes, Telecommunications Energy Conference, 1999 (INTELEC ’99), pp. 9-3, 1999.

APPENDIX

Table 8 Summary of the performance of individual loads on voltage sag

Depth

Duration in cycles

10 20 30 40 50 60 Observations

70 No Effects No Effects No Effects No Effects No Effects No Effects

Noticeable decrease in speed in motor accompanied by sound, no effect on VSD, no effect on IT-based equipment, dimness in lighting loads, no effect on electric kettle, oven and rice cooker, blender and fan stops operating and continue when voltage is restored, no effect on non-linear equipment and massager.

60 No EffectsFluorescent lamp switches off

Fluorescent lamp switches off

Fluorescent lamp switches off

Fluorescent lamp switches off

Fluorescent lamp switches off

Noticeable decreased in speed in motor accompanied by sound, no effect on VSD, no effect on IT-based equipment, increase dimness in lighting loads, fluorescent lamp A switches off and recovers after sag, no effect on electric kettle , oven and rice cooker, blender and fan stops operating and continue when voltage is restored, no effect on non-linear equipment and massager.

50Fluorescent lamp switches off

Fluorescent lamp switches off

Fluorescent lamp switches off

Fluorescent lamp switches off

Fluorescent lamp switches off

Fluorescent lamp switches off

Noticeable decreased in speed in motor accompanied by sound, no effect on VSD, no effect on IT-based equipment, increase dimness in lighting loads, fluorescent lamp switches off and recovers after sag, no effect on electric kettle, oven and rice cooker, blender and fan stops operating and continue when voltage is restored, image of TV distorted and recovers after sag, LED light in microwave dimmed, no effects on decoder and massager.

20

40

Fluorescent lamp switches off, computer A restarted

Fluorescent lamp switches off, computer A restarted

Fluorescent lamp switches off, computer A restarted

Fluorescent lamp switches off, computer A restarted

Fluorescent lamp switches off, computer A restarted

Fluorescent lamp switches off, computer A restarted

Noticeable decreased in speed in motor accompanied by sound, no effect on VSD, no effect on IT-based equipment except for computer A restarted, increase dimness in lighting loads, fluorescent lamp A switches off and recovers after sag, no effect on electric kettle, oven and rice cooker, blender and fan stops operating and continue when voltage is restored, increase in severity of distortion of TV image and recovers after sag, LED light in microwave dimmed, no effects on decoder and massager stops operating and recovers after sag.

30

Fluorescent lamps switches off, computer A restarted, microwave and electric kettle switched off

Fluorescent lamps switches off, computer A restarted, microwave and electric kettle switched off

Fluorescent lamps switches off, computer A restarted, microwave and electric kettle switched off

Fluorescent lamps switches off, computer A restarted, microwave and electric kettle switched off

Fluorescent lamps switches off, computer A restarted, microwave and electric kettle switched off

Fluorescent lamps switches off, computer A restarted, microwave and electric kettle switched off

Noticeable decreased in speed in motor accompanied by sound, no effect on VSD, no effect on IT-based equipment except for computer A restarted, increase dimness in lighting loads, fluorescent lamp A and B switches off and recovers after sag, electric kettle switches off and recovers after sag, no effect of sag on oven and rice cooker, blender and fan stops operating and continue when voltage is restored, image of TV distorted and recovers after sag, microwave switches off and operation had to be restarted, no effects on decoder and massager stops operating and recovers after sag.

20

Fluorescent lamp switches off, computer A restarted, microwave and electric kettle switched off

Fluorescent and incandescent lamp switches off, computer A restarted, microwave and electric kettle switched off

Fluorescent and incandescent lamp switches off, computer A restarted, microwave and electric kettle switched off

Fluorescent and incandescent lamp switches off, computer A restarted, microwave and electric kettle switched off

All lighting loads switches off, computer A restarted, microwave, electric kettle and massager switched off

All lighting loads switches off, computer A restarted, microwave, electric kettle and massager switched off

Noticeable decreased in speed in motor accompanied by sound, no effect on VSD, no effect on IT-based equipment except for computer A restarted, all lighting loads switches off and recovers after sag electric kettle and rice cooker switches off and recover after sag, no effect of sag on oven, blender and fan stops operating and continue when voltage is restored, image of TV distorted and recovers after sag, microwave switches off and operation had to be restarted, no effects on decoder and massager switches off and had to be restarted.

10

Fluorescent lamp switches off, all IT-based equipment switches off, microwave, electric kettle and all non-linear equipments switched off

Fluorescent and incandescent lamp switches off, all IT-based equipment switches off, microwave, electric kettle and all non-linear equipments switched off

Fluorescent and incandescent lamp switches off, all IT-based equipment switches off, microwave, electric kettle and all non-linear equipments switched off

Fluorescent and incandescent lamp switches off, all IT-based equipment switches off, microwave, electric kettle and all non-linear equipments switched off

All lighting loads switches off, all IT-based equipment switches off, microwave, electric kettle, all non-linear equipments switched off and massager switched off

All lighting loads switches off, all IT-based equipment switches off, microwave, electric kettle, all non-linear equipments switched off and massager switched off

Noticeable decreased in speed in motor accompanied by sound, no effect on VSD, computers restarted, printers and scanner switches off and operation have to be restarted, hub and LCD monitor switches off and recovers after sag, all lighting loads switches off and recovers after sag electric kettle and rice cooker switches off and recover after sag, no effect of sag on oven, blender and fan stops operating and continue when voltage is restored, TV switches off and recovers after sag, microwave switches off and operation had to be restarted, decoder switches off and recovers after sag and massager switches off and had to be restarted.

21

0

Fluorescent lamp switches off, all IT-based equipment switches off, microwave, electric kettle and all non-linear equipments switched off

Fluorescent and incandescent lamp switches off, all IT-based equipment switches off, microwave, electric kettle and all non-linear equipments switched off

Fluorescent and incandescent lamp switches off, all IT-based equipment switches off, microwave, electric kettle and all non-linear equipments switched off

Fluorescent and incandescent lamp switches off, all IT-based equipment switches off, microwave, electric kettle and all non-linear equipments switched off

All lighting loads switches off, all IT-based equipment switches off, microwave, electric kettle, all non-linear equipments switched off and massager switched off

All lighting loads switches off, all IT-based equipment switches off, microwave, electric kettle, all non-linear equipments switched off and massager switched off

Noticeable decreased in speed in motor accompanied by sound, no effect on VSD, computers restarted, printers and scanner switches off and operation have to be restarted, hub and LCD monitor switches off and recovers after sag, all lighting loads switches off and recovers after sag electric kettle and rice cooker switches off and recover after sag, no effect of sag on oven, blender and fan stops operating and continue when voltage is restored, TV switches off and recovers after sag, microwave switches off and operation had to be restarted, decoder switches off and recovers after sag and massager switches off and had to be restarted.

22