Unknown kW rating of motor 1

[kentokyo]

Hi All,

I'm on site at a new installation and we have been supplied with a Siemens inverter driven motor. On the plate, it specifies it as a 22kW (40A) and it is in a 37kW frame.

The motor (for a chain conveyor) is according to the design, meant to be a 37kW motor, however we are assured by our supplier that the motor is in-fact plated incorrectly (which I have never come across) and is a 37kW motor rather than a 22kW, as per the plate.

Is there any way I can off-line test this motor whilst on the conveyor to verify it's kW rating?

Thanks for your help.

 

[Skogsgurra]

This might be an "87 Hz case" where the speed is taken up to 1.73 times base speed and you, therefore, get 37 kW out of the motor - even if the plate says 22 kW at base speed.

It is very likely as the ratio between 37 and 22 is close to 1.7, which is a good approximation for sqrt(3).

If that is the case, there is nothing to worry about. You may need to read up on motor torque, speed and power.



Gunnar Englund

http://www.gke.org

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100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

 

[jraef]

Wow Gunnar, nice theory! I would never have thought of that but it makes perfect sense in that the OP did not state the intended use or how it was controlled. PLS for you my friend.


"If I had eight hours to chop down a tree, I'd spend six sharpening my axe." -- Abraham Lincoln
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[Feg]

I have been dealing with SIEMENS for a number of years and I do come across quite a few specials, if you look at the model no, at the end it may have a Z. This Z indicates a special option. I have in the past come across larger frames with lower kw rating from SIEMENS.

Are you talking about 2 pole speed, 22Kw in 2 pole should be in frame 180M, 37kw 2 pole should be in frame 200L. If you are talking about 4 pole then the difference is 2 frame sizes (22Kw 4pl 180 frame, 37kw 4pl 225 frame as 30Kw is in frame 200)

I have never seen SIEMENS putting on a wrong nameplate but there is a first time for everything

Feg

 

[Laplacian]

Need to verify torque requirements for this application. The converyor sounds like a friction load where torque requirements increase as speed increases. If the motor is rated as Gunnar suggests, then motor rated torque will remain constant above based rated speed. Basically, you only have the torque available of the 22kW machine at full speed.

 

[Laplacian]

Or they may have given you a derated 37kW frame for a better turn down ratio for running at reduced speeds.

 

[DickDV]

The OP didn't mention explosive hazard ratings but it is possible that a 22kw motor would be placed in an oversized frame to meet surface temp limitations in hazard-rated environments.

It's worth checking especially as the motor is running on inverter power.

 

[ozmosis]

Gunnar
Unless the OP is running at 690Vac then I would guess the 87Hz function of using the delta (or Star) winding in the higher voltage may not be the case with this one at this power rating. The 87Hz is typically used on sub 7.5kW applications that have 240/400V Delta/Star configuration where the VFD will output 400V into the Delta winding configuration.
Most Siemens motors are 240/400 Delta/Star to about 7.5kW and 400/690 Star/Delta above.
Kentokyo
Check your Siemens nameplate and look at the part number and see if the last digit has a "-Z". If it has, then this means there is something special about the motor from the factory. The serial number will inform the factory what the 'special' is.

 

[Skogsgurra]

Right Patrick!

The magical "Z" has fooled me more than once.

Met a friend of yours today, at SBT.

Gunnar Englund

http://www.gke.org

--------------------------------------
100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

 

[ozmosis]

I just read the comment from Feg, sorry I didn't mean to duplicate your comment, just didn't read the whole thread fully.

Do I still have friends in SBT?

 

[Skogsgurra]

Yes - it seems so. But this was in Stockholm. Or rather at sea. I was checking out bearing damages caused by inverters onboard a ferry and a guy that has been with L&G for a long time mentioned Congleton. And, as so often happens, I mentioned that I know you.

Gunnar Englund

http://www.gke.org

--------------------------------------
100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

 

[ScumPunk]

Gunnar,
I hope they didn't mention Congleton with regard to their problems - we're having a bad enough time as it is at the moment
Ozmosis - I'm afraid I have to disagree with your comment re. motor voltages. The 230/400 configuration is shown as standard up to 45kW in the motor catalogue.
One idea, is the motor in the OP a 6 pole motor for example? It might explain the size difference...
Regards,
Mort

 

[ozmosis]

Fair point Mort, but not at 40A 240V I would say.
I don't think gunnar was undermining Congleton-he knows I used to work out of there, that's all.

 

[ScumPunk]

I'm sure he wasn't - I was joking....
Looking at the 1LA7 motor guide - 22kW 4 pole is rated at 41.5A at 400V/50Hz, frame size is 180L.
6 pole 22kW is 200L frame size, but rated current is 45.5A.
Could kentokyo give us the MLFB of the plate, that would shed some light on it? I don't see him mention 240V in the OP?

Cheers,
Mort