motor earth fault set point
motor earth fault set point
(OP)
HI
How to select the earth fault protection set point for the low voltage electrical motors? Does it depends on the system voltage, motor size? Earthling system type?
I can make an example: 0.4kv 37kw induction motor, neutral is direct connected to ground?
How to select the earth fault protection set point for the low voltage electrical motors? Does it depends on the system voltage, motor size? Earthling system type?
I can make an example: 0.4kv 37kw induction motor, neutral is direct connected to ground?
RE: motor earth fault set point
RE: motor earth fault set point
RE: motor earth fault set point
"...#1. How to select the earth fault protection set point for the low voltage electrical motors? #2. Does it depends on the system voltage, motor size? Earthling system type? ..... an example: 0.4kv 37kw induction motor, neutral is direct connected to ground?"
#0. To answer your question, I refer to IEC,BS,NEMA,NEC ; sorry NO [good/definitive ] advice from the mentioned publications/standards.
#1. I am of the opinion that the following should be taken into consideration:
a) say (1.5 x the leakage current) of a [health] motor. See also f) below.
b) not exceeding say [0.03 x motor rated current].
c) fire fighting pump motor may be set in the same way but only (alarm) [no tripping ! is allowed ]
e) essential loads may set 0.1 x higher or [only alarm without tripping].
f) for EF protection, (one zero-sequence CT) is preferred, instead of the residual/summation of three CT method.
#2. Yes. See #1. above.
Che Kuan Yau (Singapore)