Effect of Voltage Sags on Sensitive Loads in the 240 V/50 Hz Malaysian Distribution Systems (original) (raw)
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IET Conference Publications, 2009
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. Although, 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 behaviour 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.
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This article deals with the assessment of the reliability of sensitive equipment due to voltage sags. The most frequent problems of power quality are voltage sags. Equipment that cannot withstand short-term voltage sag is defined as sensitive device. Sensitivity of such equipment can be described by the voltage-tolerance curves. A device (generator) to generate voltage sags (also interruptions) with duration at least 1 ms has been designed and developed for this purpose. Equipment sensitive to voltage sags was tested using this generator. Overall, five types of sensitive equipment were tested: personal computers, fluorescent lamps, drives with speed control, programmable logic controllers, and contactors. The measured sensitivity curves of these devices have been used to determine the number of trips (failures) due to voltage sags. Two probabilistic methods (general probability method and cumulative probability method) to determine probability of equipment failure occurrence are used. These methods were applied to real node in the distribution system with its actual performance of voltage sags/swells. The calculations also contain different levels of sensitivity of the sensitive equipment.
2019
Frequent voltage sag events at Gebeng Industrial Area posed a significant impact on the process lines of a petrochemical plant. Several of its important electrical/electronic equipment which is controlled by AC contactors had tripped, resulting in long downtime and high losses. In order to understand this power quality issue, the plant had collaborated with TNB Energy Services, a wholly owned subsidiary of Tenaga Nasional Berhad to evaluate its equipment immunity levels with respect to voltage sag. This paper aims to study and compare the immunity level of the AC contactor which is used in industrial operation over period of time. The contactors were sampled randomly and test was conducted at site. The response is benchmarked against Malaysian Standard MS IEC 61000-4-11 voltage-tolerance curve. Subsequently the result for test conducted within period of four (4) years is presented. Three out of five AC contactors show weakening of immunity levels and four out of five contactors exhi...
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The aim of this paper is to analyze the sensitivity of various compact fluorescent lamps (CFLs) which are used in residential and commercial applications during voltage sags. Laboratory tests were performed on different CFLs commonly available in the market. The tests are based on recent testing standards and utilizing a modern industrial power corruptor. For predefined malfunction criterion of zero illuminance condition, sag depth and duration are varied to construct individual voltage immunity curves. Experimental results show that all CFLs are sensitive to voltage sags and vary in a wide range. It also proves that some brands of CFLs having similar power rating are sensitive to both sag magnitudes and its duration.
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WSEAS Transactions on …, 2010
The aim of this paper is to analyze the sensitivity of various compact fluorescent lamps (CFLs) which are used in residential and commercial applications during voltage sags. Laboratory tests were performed on different CFLs commonly available in the market. The tests are based on recent testing standards and utilizing a modern industrial power corruptor. For predefined malfunction criterion of zero illuminance condition, sag depth and duration are varied to construct individual voltage immunity curves. Experimental results show that all CFLs are sensitive to voltage sags and vary in a wide range. It also proves that some brands of CFLs having similar power rating are sensitive to both sag magnitudes and its duration. Finally a method to improve the sensitivity of CFLs to voltage sags is implemented. This technique increases the holdup time of the dc bus voltage by connecting additional dc capacitance at the rectifier output of the CFL's ballast circuit.
Voltage sag susceptibility of 230 V equipment
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The ITI curve developed by the Information Technology Industry Council (USA) describes an AC input voltage envelope, which typically can be tolerated by most information technology (IT) equipment supplied by nominal 120 V 60 Hz electricity networks. Although the curve ostensibly applies only to IT equipment supplied at 120 V 60 Hz it is often used throughout the electricity supply industry, including at other nominal voltages and frequencies, without modification or consideration of applicability to provide an indication of the input voltage tolerance of a wide range of equipment. This paper details a preliminary study aimed at developing an ITI style curve to suit 230 V 50 Hz electricity networks. A range of domestic and industrial equipment has been tested to determine voltage sag susceptibility. Overall, results for domestic appliances show that equipment connected to the Australian 230 V 50 Hz electricity network has voltage sag immunity considerably better than that defined by the ITI curve. The same may be said for the majority of industrial equipment tested. As such, the suitability of the ITI curve in describing a sag immunity envelope for individual pieces of equipment connected to 230 V 50 Hz electricity networks is highly questionable.
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Circuit theory models are used to estimate the number of voltage sags in the supply to a paper mill. For every voltage level, the radius of the exposed area (the critical distance) gives the expected number of sags. As the main sensitive load is formed by large adjustable-speed drives, a classification of sags into four types is used. The conclusion of the paper is that the equipment should first be made resilient against sags due to single-phase faults at 400 kV. These faults cause the majority of sags. Sags due to three-phase faults are more severe (especially due to faults at 11 kV), but are less common.
2008 IEEE/PES Transmission and Distribution Conference and Exposition, 2008
Power quality is a compatibility problem; it can be solved either by making the power better, or by making the loads tougher. The latter approach is encouraged by power quality immunity standards, which are rapidly changing. SEMI F47 has just been updated; IEC 61000-4-34 is starting to take effect internationally and soon in Europe; and other standards are coming on line. This paper discusses the author's practical experience applying these standards to industrial equipment that ranges from industrial drives to automobile robots to infant formula factories, throughout the world. The authors will also introduce and explain the necessary requirements of the test instrument that is used for voltage sag testing.
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Voltage sag is regarded as one of the most harmful power quality disturbances due to its costly impact on sensitive loads. The vast majority of the problems occurring across the utility, transmission and industrial sides are voltage sags. The source of sag can be difficult to locate, since it occurs either inside or outside facilities. So, this paper analyses some aspects of voltage sag such as the cost of voltage sag, their characteristics, types of voltage sag, its occurrence, percentage of sag present in power system, acceptable level of voltage sag curve, voltage sag indices, its economical impact, ways to mitigate the voltage sag and finally few devices used to mitigate voltage sag.