Motor Space Heater Circuit

[mityeltu]

I have a 460v motor with separate circuit for the heater. That is, the heater is NOT fed from the motor control circuit. Odd, I know, but still.

My question is, is there a standard (IEEE, NEMA, IEC, anything) that tells HOW this circuit should be confugured?

It appears as though this heater (3 element) is fed from a single phase breaker which tells me they are either in series or parallel, but I would like to have some cannon fodder before I go mouthing off to the electricians.

Any thoughts?

 

[kingpb]

If it is not fed from the motor controller, and is a separate source, somehow it needs to be connected through the controller otherwise how are you making it come on when motor is off, and go off when motor is on?

Also, if it is a separate source, the controller needs to be identified that there is multiple sources of power in the controller, otherwise this could be a safety issue.

Without knowing the type and rating it is not possible to answer your series parallel question. However, the following link directs you to some literature. Select Service, then Product Service Bulletins, look for issue 4: which explains some about heater types.

http://www.usmotors.com/default_literature.htm

 

[Designer69]

i doubt there are standards that cover space heater wiring, unless NEMA MG1 has verbiage on it.

typically they are just powered off of a b contact from the motor breaker.

 

[mityeltu]

The separate power issue is actually what brought this to my attention. The electricians were about to perform some PM on it and discovered that there was still power after following the drawings for lock out. The heater was not on any drawings. I don't know if this was an afterthought or what. I'm fairly new to the plant. I have never seen one wired this way.

It appears from the electricians as though the heater is always on. That should make it last longer.

Thanks for the info on heaters. I'll look into MG1, but I don't recall anything specifically about heater wiring methods in that one.

Thanks. If you think of anything else, please let me know.