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22Kw motor isolator

22Kw motor isolator

22Kw motor isolator

(OP)
I’ve got a temporary 22Kw motor running on a 63amp isolator. Think the isolator is rated AC3 for 11Kw . If the isolators not being used to switch the load is this okay?

RE: 22Kw motor isolator

Dear Mr.Jk1996 (Electrical)(OP)7 Jun 22 15:13
"...I’ve got a temporary 22Kw motor running on a 63amp isolator. Think the isolator is rated AC3 for 11Kw . If the isolators not being used to switch the load is this okay? "
NOT ok. An isolator AC20 per IEC is NOT intended to switch any current. Replace it with a breaker or a load-break switch, that is good for 22kW motor (instead of 22Kw per SI) .
Che Kuan Yau (Singapore)

.

RE: 22Kw motor isolator

I think it is OK as you won't be switching the motor using the isolator.
AC3 rating is specifically about switching squirrel cage induction motor current and capability of the isolator to successfully interrupt.
When it comes to load current carrying capability, 63A rating of isolator is good enough.

RE: 22Kw motor isolator

@ Dear Mr. RRaghunath (Electrical)8 Jun 22 06:21
"...#1. I think it is OK as you won't be switching the motor using the isolator. #2. AC3 rating is specifically about switching squirrel cage induction motor current and capability of the isolator to successfully interrupt"..
#1. Per IEC 60947-3, an (isolator=disconnector) AC20 [is intended for make/break without load/current]. The circuit shall have a breaker/load break switch at the up-stream. To (prevent any inadvertent operation by the operator), this isolator must interlocked to switch off the up-stream and labeled/forewarn the operators that it shall [not be used for on/off switching with load].
#2. Per IEC 60947-4-1, AC3 is utilization category for contactors. For switching devices, the utilization categories are AC20...AC23 . A AC23 would be capable of switching motors.
Che Kuan Yau (Singapore)

RE: 22Kw motor isolator

(OP)
Thank you for your replies. So if it’s not being used to break the load the current is okay, the FLC of the motor is 40amp? This is temporary so ideally it should be labelled. What are your thoughts?

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