| Title |
Operating Characteristics of Molded Case Circuit Breakers by Harmonic Currents |
| Authors |
Jeong-Chay Jeon ; Jae-Geun Yoo ; Sang-Ick Lee |
| Keywords |
Malfunction ; Nuisance tripping ; Molded case circuit breakers ; Harmonic currents |
| Abstract |
Malfunction and nuisance tripping of molded case circuit breaker(MCCB) caused by harmonic currents have been reported. But no data is available on the behavior of MCCB under harmonic currents. This paper tested the effects of harmonic currents on four common types of MCCB(thermal, thermal magnetic, magnetic and electronic types). Results of experiment detected no nuisance tripping with any of the breakers tested under test currents, included harmonic current, below rated currents. Additionally it was found that varying harmonic loading conditions did not affect manufacturer specified trip times for thermal only and thermal magnetic circuit breakers. However, under overloaded conditions, trip times of the magnetic only circuit breakers were gradually slowed according to increasing of harmonic currents, and it could cause hazardous overheating of cables. So, the use of magnetic only circuit breakers in the place harmonic currents are serious must be avoided. |