Publication: Effect harmonic on power system equipments
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Date
2010-04-01
Authors
Lee, Choon Hooi
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Abstract
Harmonic is a very serious problem in power system. Some of the power system equipment such as current transformer, circuit breaker and over-current relay are experimented under harmonic current distortion condition to analyze its performance. The harmonic components with different frequencies will increase total load current and may be affect the power equipment such as relay and circuit breaker cannot operation. This research presents the effect of harmonic on disturbing the accuracy of current transformer, analyze the performance of circuit breaker under harmonic condition and analyze the accuracy of over current relay in either sensing the load current or making decision to send tripping signal. The source of the system was voltage supply of 240V, 50Hz. The rectifier circuit is used as non-linear load in whole project. The total harmonic distortion for input current would change by varied the variable resistor and variable capacitor. The result is measured by measurement tools such as FLUKE 43B, multi-meter, and so on. The result is collected and analyzed. The practically result are compared with theoretical value and the percentage of error is determined. Based on the research, over-current relay, circuit breaker and current transformer cannot function in good condition due to presence too high of harmonic current. Most of power equipment cannot support too high of harmonic. Protection system is build with relay, circuit breaker and current transformer. Therefore, harmonic is a very important fact that should consider when installs the protection system in a building. Harmonic will cause overheat to the electric equipment and damages the equipments as the load current is higher than normal rating.