1395 drive has field loss

[Bob Aber]

I have a 500 hp. Drive that has a field loss fault. changed drives, no help. Changed motor, still has field loss fault. put a resistive load on field , field is good. Got a new motor and just hooked up field, still have field loss. hook resistive load back on drive. drive field is fine.. Any ideas??

 

[jraef]

Well since you have already taken the expensive route of replacing both the drive and the motor, all that's left is the cheap stuff; the wires to the field of the motor, including all of the connectors, and the phase sequence of the AC feed to the field supply (it is phase sensitive for some reason); it can only be connected to L1 and L3.

 

[rdrast]

What is the actual motor field rated for?
How is the drive set up (Voltage mode or current)?
How is the field wired (HV or LV?)
Was any work recently done to the drive/motor/connections?

 

[widelto]

Have you measured field voltage at motor terminal and drive terminals, have you checked field current.
You mention nothing about motor type, normally DC motors has four field terminals, F1, F2, F3 and F4. For 150 volts F1 & F3 are tied, F2 & F4 are tied, connections are between F1 and F2(parallel). For 300 volts F2 & F3 are tied, connections are between F1 and F4(series).

 

[Bob Aber]

We have checked Motor field connections, tied in a dummy load at motor on the field, drive did not fault on field loss. Have changed out all the boards multiple times. wWe did get the field to stay on this morning but it will not regulate the field current. Have 420Volts dc and 16amps on field. checked field parameters, the drive knows that it it putting out 16 amps. we have the field set for 11.8 amps and the drive see's 16 amps and won't regulate the current down.

 

[osmanmom]

We have checked Motor field connections, tied in a dummy load at motor on the field .

what means "dummy load at motor on the field"

control room or machine site ?

 

[duckman]

Was this motor previously operating, or is this commissioning?
l will answer your question "O", they are saying they have put a dummy load on the field connection at the motor end in situ.
Is there the opportunity to put a basic thyristor control on the field, to confirm proper operation, wouldn't be the first time a faulty VSD was replaced with another faulty VSD

 

[duckman]

RE read post, you now say drives puts out 16 amps, but does it still trip on field loss? or won't it regulate speed/torque?

 

[DickDV]

I believe this drive is identical to the Reliance Flex3000 in case someone has experience with that unit. I suspect that, given the above test data, the field loss parameters are not set up properly. And, if this is a regulating field regulator, the parameters don't seem to be set up properly for regulating to nameplate field current either.

These are fine drives and the parameters provide for full comfigurability. But, you have to know how to do it. Sounds to me like programming issues.

 

[Bob Aber]

Thanks for all your help. The phase sequence was off going to field circuit. The wires were going to phase 1 and 3 but they were hooked up backwards..reversed wires and the field started working..

 

[alan_505]

Hi DickDV,

The Reliance Flexpac3000 is not the same as the 1395 drive.

The 1395 is an AB drive.

The AB 1397 DC drive is the equivalent of the Reliance FP3000.

Alan

 

[DickDV]

OK, Alan, thanks for the correction. Close doesn't count in this business, does it?