Motor heating and cooling time constants - Heat run test

Question

Motor heating and cooling time constants - Heat run test

raghun (Electrical)

(OP)

19 Jan 08 22:36

I have Heat run test results for a motor. Can I calculate Heating and Cooling Time constants from this data!
Thanks.

7anoter4 (Electrical) · Answer 1 · 2008-01-24 04:52:16

Hi Raghun,
According to Rudolf Richter Electrical Machine vol I
[Erster Band-zweite verbesserte Auflage Basel 1951]
The electric motor heating equation is as follows:
?=Theta
Theta=ThetaMax*(1-exp^(-t/T))+Thetao*(exp^(-t/T))
where Theta is the actual temperature ThetaMax is the maximum temperature reached by a machine
and Thetao is initial temperature.
T is the heating constant and t is the heating time.
So T=t/Ln(ThetaMax-Thetao)/(ThetaMax-Theta)
R.Richter took the same constant as cooling constant.
Theta=Thetai*(exp^(-t/Tcooling))
Where Thetai is the initial cooling temperature
According to Siemens Handbook for Electrical Engineer chpt.7.5.3 Tcooling=(1.4 -2) *Theating
Best regards

raghun (Electrical) · Answer 2 · 2008-01-24 05:05:59

Thanks 7anoter4 for the info.
The cooling constant can be 3-6 times the heating constant as per the literature of ABB make SPAM motor protection relay. This is also seen in the data sheets of HV motors many times.

slavag (Electrical) · Answer 3 · 2008-01-24 11:08:46

Hi Raghun.
I rcommend to you check ABB make REM610, more information then SPAM150.
Are you have for SPAM application example too, or only manual?
Regards.
Slava

raghun (Electrical) · Answer 4 · 2008-01-25 03:55:00

I do have SPAM Calculation tool (EXCEL) by ABB also. I will check REM manual. Thanks slavag.

Member Login

Come Join Us!

Posting Guidelines

Link To This Forum!

Motor heating and cooling time constants - Heat run test