Abb acs800 drive-encder issue (fault-7302)

I AM HAVING A PROBLEM WITH THE MOTORS 1250HP MOTORS-2NOS) RUNNING ON ABBACS800 DRIVES WITH FIRMWARE AMXR7320.

BOTH THE MOTORS (MOTOR-A & B) HAVE INDEPENDENT ENCODERS.

WHEN WE RUN THE MOTORS IN ENCODER MODE, THE MOTORS ARE GIVING LOUD NOISE.

NO NOISE APPEARS FROM THE DRIVE WHEN IT RUNS IN INTERNAL MODE. WHEN I START MOTOR-A WITH ENCODER IT TRIPS WITH A FAULT 7301.

WHEN WE RUN THE MOTORS TOGETHER IN INTERNAL MODE, ONE OF THE DRIVE TRIPPED WITH A FAULT "7302, ENCODER A<>B, PULSE ENCODER PHASING IS WRONG. WHEN WE LOOKED AT THE WAVEFORM, THE CHANNEL A IS LEADING B. SO I WONDER WHY THE FAULT 7302 IS APPEARING? ATTACHED PHOTO OF THE WAVEFORM FOR REF.

WE HAVE REPLACED THE ENCODER AND RTAC CARDS ON BOTH THE DRIVES BUT THE PROBLEM STILL PERSISTS.

MAY I KNOW WHAT ARE THE OTHER CHECK I CAN CARRY OUT TO RESOLVE THIS ISSUE?
Regrads
BKR

Hello

Before this issue was there any faults or other work done to the drives, motors or encoders. Are you using fiber optics to link the drives? Could they been damaged?

Tom

Thanks Tom for the reply.
Yes the communication between the drive is trhough fiberoptics.
The drives are with RDCO-01 & the communication Module is ADVANT/N-FB
No jobs are carried out on the Drive or Motors.
But when the Drive-B started to trip with Encoder Fault 7301, the Encoder was replaced. This is the only job carried out.
Rgds,
BKR

Getting an encoder fault while operating on sensorless (DTC) indicates that some of the parameters are not set properly.

I would turn off all references to encoders in the software and operate both motors on DTC first, tuning up the speed loop in Group 23 and verifying good operation on DTC first. Then I would introduce the encoder and verify operation in that mode. At parameters 02.17 and 02.18, you can compare the encoder feedback (measured speed) with the DTC calculated speed (calculated speed). These should be very close. If not, continue to refine the encoder feedback settings before throwing the drive over to encoder feedback. If these two parameters are far apart, you will get a fault when you switch to encoder feedback.

Hello Dick,
Thanks for the reply. Today I tested only one Motor-A. The other motor is not online because the encoder is disconnected.
The Drive-A and it was tripping with an Encoder fault 7301. So set the parameter to "Alarm" mode and then tested the drive.
There is lot of variation between the Estimated & Measured Speed.
I am not able to attach the trend here. So kindly look at the below table.
Speed Reference
109.1
109.1
109.0
109.0
109.0
109.0
Speed Measured 01.03
126.05
123.43
61.92
105.01
104.75
101.52
Speed Estimated 01.02
109.3
108.8
114.9
109.2
107.6
109.1
Motor Torque %
+0.93
-1.24
-3.17
-0.23
+0.79
1.39


It would be nice to know how I can tune up Group 23? Please note that the firm ware is AMXR7320.
Awaiting for an early reply.
Thanks a lot
BKR

What do you have in parameters 23.01, 23.02, and 23.03?

23.01, 23.02, and 23.03 are 0
Thanks
BKR

That's your problem! The speed loop has no gains entered into it. Put 40 into 23.01, 1.00 into 23.02, and leave 0 in 23.03.

Run your machine and see if the speed error goes away.

Thnx Dick.I will try wht u ve said.
BKR