Change Motor Direction with Encoder

I have a 30 hp ac motor connected to a powerflex 700s ac drive the motor has a 1024ppm encoder.

It is running but in the wrong direction and when i swap t1,t2,t3 to change the direction at the drive or motor it still goes in the same direction but jerks? Why?

I think it has something to do with the encoder?

How can i get it going in the right direction?

Change only T1 & T2 not all three! Preferably on the line side of the VSD changing at the motor may be causing issues such as jerking.

I only swapped two leads.Just a typo

Problem has something to do with the encoder.

Only encoder issues I have come across is where 2 AC drives run a single conveyor that has caused alot of jerkiness....fixes were opened the encoder j-box & tightened wires, replaced encoder due to shaft breakage(use plastic tube & hose clamps if no shaft available, replaced encoder due to internal failure....I think your on the right track with the encoder with regards to jerkiness but I havent heard of encoders controlling phase rotation.

Kid,

Try swapping A and /A with B and /B respectively. I've had SEW Eurodrive VFDs sensitive to phasing on the encoder. I imagine it has something to do with the drive turning the motor one way, and getting encoder feedback that it's turning the other way. Swapping encoder phases should solve that. The Z and it's complement should be fine and shouldn't be changed. Depending on the drive, there may be a parameter you can change too, instead of physically re-phasing the encoder.


-rpoet

Swapped A+ with B+ Problem solved. Thanks

Just to give you a bit more background. You have what is called a quadrature encoder. It produces four streams of pulses, A, inverse A, B, and inverse B. When the encoder shaft is rotating in "encoder forward" direction, the B pulses lag behind the A pulses by 1/4 of a cycle or 90 degrees. When the encoder shaft is rotating in "encoder backward" direction, the B pulses lead the A pulses by 1/4 of a cycle or 90 degrees.

When setting up a drive/motor system with an encoder, you have to set the "drive forward" and the "encoder forward" to be the same. The way that is done is to exchange the A and inverse A lead pair with the B and inverse B pair at the drive terminals.

Sounds like that is just what you did to get the system to settle down.

Dick

I have com,v+,A,A-,B,B- and i swapped b,b- only.

What would happen is when i reversed rotation on the motor it would jerk almost like an indexer or something.

Once i swapped these and the rotation it ran in the right direction with no jerk?

To clear this up for other readers ...

Swapping channels on an encoder does not change the direction of the motor. It only changes the direction that the controller thinks the motor is turning. On a differential encoder, you do not need to swap all channels to change the indicated direction. You only need to swap A and A Not or B and B Not. You can swap just A and B on a differential encoder but if you do that without swapping A Not and B Not you will be losing some of the noise cancellation properties of the differential signals. If the encoder does not have an A Not channel (it is not a differential encoder) then you swap A & B.

And changing leads on the line side of a VFD will never have an affect on motor direction.