Correction of circuit breaker nuisance tripping on a 600 KVAR capacitor bank installed in a manufacturing plant done by Controlgear Electric Corporation (CEC)

Date

12-2014

Degree

Bachelor of Science in Electrical Engineering

College

College of Engineering and Agro-Industrial Technology (CEAT)

Adviser/Committee Chair

Elvin D. Dulce

Abstract

Power factor correction is one way of improving the power quality of an electrical system. A facility can avoid extra charges in the electric bill by having a power factor above the limits set by the distribution utility. An effective way of improving power factor is through the installation of a capacitor bank in the electric system. However, due to the advancement of modern electronics, non-linear loads such as Variable Frequency Drives (VFD) because common in facilities with induction motor loads. The electrical harmonics produced by VFD's was absorbed by the capacitor bank which caused the circuit breakers protecting the capacitor step to trip. The tripping of the circuit breakers hinders the capacitors from connecting to he system, making the capacitor bank useless. CEC, a manufacturer of capacitor banks and other electrical equipment and provider of electrical services, has conducted an analysis to address the problem in one of its manufactured capacitor bank installed in a manufacturing plant. To determine the magnitude of current passing through the capacitors and the circuit breakers, the circuit breakers were removed to measure the current entering the capacitors without interruption. It was found out that the RMS current entering the capacitor steps was very high due to harmonies (ranges from 502.5% and 205.5% of the rated current which is 60A). Also, the calculated harmonic resonant order of the electric system was close to the characteristic harmonic orders of the VFD's which causes the occurrence of harmonic renosance. After replacing the VFD's with a higher pulse version and connecting detuned reactors in series with the capacitors, the current has reduced to the range of 100.5% and 101.5% of the rated current and the tripping has stopped from recurring.

Language

English

Location

UPLB Main Library Special Collections Section (USCS)

Call Number

LG 993 2015 E64 /P47

Document Type

Thesis

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