Motor 250KW Seimens overload and temperature rising

[Sumair786]

Hello everyone,
I have rewind a Seimens motor 250KW with exactly same data as original and motor is consuming higher ampere against original, motor details are
Atlas copco compressor
Rated ampere 445 as per name plate
Current ampere on start initially it was 515 the. Slowly rising and now it is 540 and temperature rising too i don’t have much knowledge about compressors so i need some expert advice anymore details you need I’ll provide ASAP
Thanks alot

 

[FacEngrPE]

This could be a motor problem or a compressor problem.
The 250kW motor is in the size range that typically would be a screw compressor.
Screw compressors are positive displacement compressors. A pressure rise across the compressor that is more than design will overload (over torque) the motor.
The other thing to check as a first pass is that motor amps on all phases are close to equal.

See thread237-468259

To go further with advice we need to know more about your compressor.
[ul]
[li]Model no[/li]
[li]Type of capacity control (VSD modulating vs load / unload etc).[/li]
[li]Operating data from the compressor control panel.[/li]
[li]etc[/li]
[/ul]

 

[che12345]

Please furnish more detail.
1) on electrical/motor
a) measure all the three line voltage at i) no-load, ii) full-load.
b) measure all the three line current at i) no-load, ii) full-load.
c) check the motor cooling fan and ventilation is not blocked.
2) on the compressor
a) check for any blockage.
b) check for any broken parts.
3) on mechanical structure
a) check bearing temperature.
b) check bearing lubrication.
4) BTW in SI unit, power is in kW, not KW.
Che Kuan Yau (Singapore)

 

[zlatkodo]

At first sight, it seems that the issue might be related to the compressor rather than the motor.
Has the true cause of the previous failure been identified and resolved?
Another point to clarify is the statement:

“I have rewound a Siemens motor 250KW with exactly the same data as the original.”

What exactly does that mean?
Many winders consider only the turns per coil, but not the coil-span, number of circuits, type of jumpers, lap or concentric winding, and other factors.
Changes in any of these aspects can impact the motor’s functionality.
ACW-News

 

[Sumair786]

Sorry for late answer but the coil-span, number of circuits, type of jumpers, are intact as per original winding even though there are many compressor installed side by side and some of them are are rewinded by our company and all of them are almost on original ratings but got problem with this motor only

 

[Gr8blu]

Did you run a core loss test on the stator iron both before and after burn out? A rise in core loss should have raised a flag that the burn created (or at least increased) a problem with core lamination insulation condition. More eddy losses means more current required - which appears as higher line current. Still, unless the damage was SEVERE (which probably means you shouldn't have tried to rewind it at all), the differential between "normal" and "now" should not be anywhere near +20%.

Turn-turn and/or phase/phase faults will result in an observed increase in the line current as well - which may be relatively slow and gradual or catastrophic and instantaneous.

Converting energy to motion for more than half a century

 

[davidbeach]

Why was the motor rewound in the first place?

When one this sentence into the German to translate wanted, would one the fact exploit, that the word order and the punctuation already with the German conventions agree.

-- Douglas Hofstadter, Jan 1982