LionelHutz... thats exactly what baffles me... the motor starter is of NEMA size 3. The MCCB inside the starter is FH100 thermal magnetic type (see attached characteristic curve) Although the magnetic trip of the MCCB starts at around 2kA, the thermal pickup is at 100A. I have been told that...
We recently had an incident at our company in which a Grounded Low Voltage motor (30kW, 480VAC, 60Hz) led to the tripping of entire MCC bus. The motor is fed through a Square D Model 6 MCC. Our System is solidly grounded and the maximum available GF current at the Motor terminals is around 20kA...
have recently come across a nuisance tripping issue that has me baffled. We have a 34.5kV switchgear feeding two Motors (call them A and D). Both motors are protected by GE 469 MMR and are exactly identical. Recently both motors tripped on Ground fault at the same time. I was called to the plant...
