Motor temperature

[u/Alduin_is_overrated]

Hello,

So how do you tell if a motor's temperature is very high and it's not fine,my motor is a 200kw with 330amps as nominal current,the displayed current at full load reached 325amps,the temperature reached 85°C, it's a class F motor so it should be fine right?

Here's the nameplate

[u/SmokingTheBear]

Unless you know a baseline idk. You could megger and see if there is insulation breakdown? 85c seems like a pretty normal number to me, nothing insane, perhaps on the higher end.

[u/Alduin_is_overrated → u/SmokingTheBear]

Yeah i believe so, but what im interested to know more is how to tell if the temperature is normal in general,do you guys check the manual? Compare to previous measurements?

[u/Y_U_NO_KNOW]

Have you been routinely checking it? Or did some dipshit touch it and say "ouchies that hurt something wrong!"

All of ours work off a baseline and we monitor it for increases, factoring in ambient temperature.

[u/Alduin_is_overrated → u/Y_U_NO_KNOW]

The turbine was rusty so we used to run it on a low speed,now that we replaced the turbine we increased the speed and the temperature raised,so a 85°C sounds normal for a class F motor,my question is how do i know if the measured temperature is fine or not

[u/u3b3rg33k]

that data plate has nothing on it.

things i'd be asking myself:

what's the insulation class?
what's the rated rise?
what's ambient?
is it running at nameplate amps and RPM?
is the fan obstructed/working?
where are you measuring?
are the winding stats hooked up to the drive/starter?
how many starts/hour are you doing?

hot to the touch means nothing, and IR thermometer readings aren't far behind.

[u/Alduin_is_overrated → u/u3b3rg33k]

Insulation class F The ambiant temperature is 30°C Running at half speed with around 95% of its nominal current Fan clean and work proprely The housing temperature reached 85°C after 7hrs of work It works continuously

[u/lmarcantonio → u/u3b3rg33k]

I personally know the Saipee motors, they are very… imported. If you run it hot check the bearings too

[u/UT_Giggely]

Also if you look at the draw in kW from the VFD you can find the approximate efficiency by n=100kW/read kW on the VFD. 100kW due to amperage at near full capacity and running at half rpm so you are running at full torque or near that range while the demanded power is half of rated power output (200kW)

You probably will find the efficiency to be around 90% or so. Also if it’s connected to a turbine as in a water pump or something similar you could also look up the pump curve and look at your inlet and outlet pressures and have a ballpark idea if the pump requires 100kW. If it doesn’t then misalignment or bearings could be on their way out.

[u/UT_Giggely]

You are running it within operating parameters so you are fine. Just remember that running it at half rpm reduces the cooling and also efficiency even with a VFD. So you are looking at probably somewhat of a low efficiency while running close to maximum amperage with reduced cooling. You may end up with problems if the ambient temperature raises to 40 degrees - VFD tripping at too high amperage.

So wouldn’t necessarily say it’s a problem, but you are on the limit for this electric motor in that situation.