Winding Temperature Stabilization
Winding Temperature Stabilization
(OP)
Dear Friends,
The Following name plate belongs to an electric motor manufactured in 1994 By SIEMENS in SPAIN:
1LA14502KF
Frame: 450
Ins.Class F (B heating)
550 kW
I= 62 A
Ia/In = 560 A
2980 rpm
Cos Phi = 0,9
Eff = 96,3 %
The motor was tested in Factory with this results:
Load% 104,9
V - 6.130 V
I - 62,2 A
597,5 Kw
Cos - 0,904
Eff - 0,9657
In this conditions the Winding temperature was Stabilize at 92,92 ºC.
Today some body are trying to use this motor with a new pump and loading with 592 kW.
The question is How to determine by calculations the new Winding temperature stabilization at 592 KW with out a new dynamometer test (Only taking account the above factory datas).
Thanks for the Inputs
Regards
Petronila
The Following name plate belongs to an electric motor manufactured in 1994 By SIEMENS in SPAIN:
1LA14502KF
Frame: 450
Ins.Class F (B heating)
550 kW
I= 62 A
Ia/In = 560 A
2980 rpm
Cos Phi = 0,9
Eff = 96,3 %
The motor was tested in Factory with this results:
Load% 104,9
V - 6.130 V
I - 62,2 A
597,5 Kw
Cos - 0,904
Eff - 0,9657
In this conditions the Winding temperature was Stabilize at 92,92 ºC.
Today some body are trying to use this motor with a new pump and loading with 592 kW.
The question is How to determine by calculations the new Winding temperature stabilization at 592 KW with out a new dynamometer test (Only taking account the above factory datas).
Thanks for the Inputs
Regards
Petronila





RE: Winding Temperature Stabilization
Temperature rise above ambient is proportional to losses.
No-load losses are about 20% of full-load losses. The remaining 80% of full-load losses are load losses which vary approximately with load^2
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RE: Winding Temperature Stabilization
the standard also implies that if the motor is run at 1.15 Per unit load, the temperature rise will be less then 90 degrees c above the nominal Ambient (130 Degrees actual copper temperature).
The actual insulation Material used is class F which means it is good for 155 Degrees c copper temperature, so in the worst case you have a 25 degree C margin.
Your 592Kw is only 1.076 P.U. (550Kw Base) so for a good first guess, your maximum design copper temperature will be 40 Ambient + 80 For 1.0 PU operation + ((7.6/15)* 10) for the 7.6% overload. or aproximately 125 Degrees C.
THe motor Insulation is rated for an absolute copper temperature of 155 Degrees C so you should be able to operate the motor at 592 Kw with at least a 30 Degree c temperature margin before insulation life is affected.
Look Here for a little more information on the temperature classes. http://w
Regards
Tom Grayson
RE: Winding Temperature Stabilization
Tom in this order of ideas, the motor could be labelled with a new name plate ¿¿ What new data could we use??
Thanks
Petronila
RE: Winding Temperature Stabilization
RE: Winding Temperature Stabilization
In reality, You ave not changed the motor, Just it's load. Renameplating the motor should be done only if the motor is physically changed to operate differently.
All you will have done is to change the load, and verified that it is operating within the design limitations of the motor.
of course the temperature calculations are based on the motor having the correct maximum ambient and umimpeded ventilation. IF your ambient is cooler then this 40 Degrees C, you are ok, If you are above 40 Degrees C then you need to watch what is happening. But still, 25C margin looks pretty good.