Siemens 6RA70

[singapore11singapore]

Hi, I have installed a Simoreg DC Master 6RA70 to a motor.
It is running forward/reverse/jog etc.....no problem.
However, the speed is slightly slow...90%, and I have maxed out the pot. Therefore is there a parameter wrong in my setup?
There was no mention of the field current on the motor nameplate. I do know the resistance of the field is 40 ohms and has 230V applied to it.
Please see attached for my .dnl file.
Any suggestion is welcome!
Regards
Singapore 11

 

[Skogsgurra]

I couldn't open that file. Does your 6RA70 have an adjustable field? If so, you should be able to find the correspondning parameter and set it lower.

If it doesn't have an adjustable field, you need to either use a transformer before the rectifier or use a resistor to drop the ecxitation voltage.

Gunnar Englund

http://www.gke.org

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

 

[lukin1977]

There are many possibilities

1. Speed base value.
Have you set the correct speed base value?
Speed base value is the value of speed at max pot (10V)

2. Max speed amount. There is a max speed limit that is usually found in the LIMITS parameters. What value it is set? What is your 90% speed in rpm?

3. Speed P value
Did you selfttune the drive?
P could be set too low. What is your speed P value?

4. Field current is too high

 

[singapore11singapore]

Hi Lukin 1977

Checked all, and it was your item 4.
As I mentioned, I am in closed loop feedback without any encoder/tacho, so field weakening was a no-no.
My motor was running only at 1100 rpm, and not 1500 rpm.
I slightly lowered the field current and the speed slightly increased.....to a point whereby I had lowered sufficiently the field current to obtain the 1500rpm.
Many thanks for your support!
S11S