3 phase motor with neutral

[johnboy6083]

the motors i wired are 15kw booster pumps fed from VSD, for southeast water. treatment works is unmanned, so im guessing they go right over the top, just in case.

 

[Engineer54]

We have several motors with internal heaters varying in age from 40 years down.........some are in pretty damp nasty places too!!! still over 200Meg on the IR test though!!!!!!

Yep!! I guess that would make sense to have a heater keeping those windings dry!! I take it, these are fairly low wattage?? Are the heaters taken out of service while the motor is running, or switched on/off by thermo device??

 

[malcolmsanford]

In what circumstances would a heater be required within a motor??

I must admit that i haven't to my recollection come across such a circumstance. The only exception has been in compressor units where a heater is employed to keep the refrigerant in a gaseous state....

We had large diesel generators similar to those they used on ships by dorman and Perkins at the pit for the gear head and the diesel was so viscous that you had to heat it up and they had heater, though perhaps not motors as such lol

But the pumps in the shaft all had heaters on them but that was for dampness to be honest., though none of them were wired off the motor

 

[Marvo]

In what circumstances would a heater be required within a motor??

I must admit that i haven't to my recollection come across such a circumstance. The only exception has been in compressor units where a heater is employed to keep the refrigerant in a gaseous state....

Maybe motors with oil lubrication might need a sump heater to maintain viscosity with the UK climate?? Just a guess.

Doesn't look like the op is going to put us out of our misery on this one. :-(

 

[Engineer54]

Thanks for the info, as i said, ...i've never come across motors with a need for heaters, except of course integral compressor motors. I can see the sense of heaters in motors that are installed in damp/humid conditions...

Haha, ...normally motors will incorporate protection devices against the build-up of heat...

Malcom,

I think most generators of any size, and especially ''stand-by'' generators will have sump heaters to keep the oil warm, ....all helps to get them started up, and protecting the metal to metal parts from the off.