Problem with motor chokes for VSD 1

[krsh]

Hello friends,
I have a problem with a motor choke(code: VW3A5104, Schneider). It is installed on the output of a 15kW VSD(code: 6SE6400-2UE31-5DA1) on a 500V/50Hz network. The problem is that the motor choke becomes very hot when we run the pump(pump application) almost full speed(40Hz) and because of that it changed the color and the isolation is damaged. The motor plate says 15kW , 23,2A, 500V, 50Hz. At 40Hz the motor takes 17,3A and the cable from the VSD to motor is about 100m. The pulse frequency is set to 4kHz. The problem is odd because the motor choke is oversized(215A).
Anyone experienced something like this before?

 

[itsmoked]

Is the choke able to dump its heat correctly? It's not in some tight box in a closed space is it?

You say the motor is taking 17.3A. How are you getting that number?

Keith Cress
kcress -

http://www.flaminsystems.com

 

[Skogsgurra]

If you put an undamped motor reactor on a 100 m long motor cable, you will get heavy ringing. Typical ringning frequency is 10 - 20 kHz.

That ringing acts as an induction oven and heats the core. If you look carefully, you will probably find that the bobins are darker close to the core. That is a clear indication that heat is generated in the core and not in the windings.

The standard remedy is to put resistors parallel to the windings. Difficult to say exactly what size and resistance you need. But think 10 - 100 ohms and around 100 W.

Schneider should be able to help.

In this picture:

http://gke.org/pub/files/dudt_filter_transient.jpg

you can see undamped ringing to the left. Ringing with damping resistors in the middle (ABB style) and ringing with diode feed-back to the DC link (Siemens).

Gunnar Englund

http://www.gke.org

--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.

 

[krsh]

Thank you Skogsgurra, this seems to be the problem.

 

[MAGTiger]

there is another possibility. If this is a 3 phase choke with a 3 leg core, then if the leads are grossly over sized by cross section, you can have a high amount of common mode current. Such a reactor will saturate in the yokes from this condition. Need to reduce the common mode current. This condition can happen even when dampening resistors are used.

Neil

 

[ozmosis]

krsh
you seem to have an odd selection of components (a Siemens VFD rated 15kw and a Schneider output dv/dt choke). I would say that one of your issues is that the output choke is rated for a maximum rated voltage of 480Vac and the VFD is rated 500-600Vac. You would appear to be operating on 500Vac as your motor is this rating, so I would think that the peak-peak voltage is possibly too high for the choke's insulation.
I might be wrong there but I would check with Schneider (SquareD) to see if this choke is suitable for 500Vac on a PWM supply.
You may also check on the switching frequency limit. I recall Schneider had numerous rules on what you can and cannot do with chokes and it might limit the CF to 2.5kHz, not the default of 4kHz the Siemens MM440 operates on.
If you are braking during operation, this will increase the peak-peak voltage even higher.