Lenze drive/ AC motor problem.

Well here it is, we got an a/c motor hooked to a d/c inverter, the motor runs great one direction with low current draw, however in the opposite direction it runs super slow and the motor current is way high, We've changed the drive, changed the cable, replaced the motor and the encoder. Everything replaced except the muffler bearings. Any ideas?, I'm stumped thanks.

Is this a recent problem or has the motor run in both directions ok in the past?

Yes this is a recent problem, that has developed into the motor overheating and not moving , twice now same everything. and yes the motor ran in both directions just fine. this is an elevator motor that constantly moves up and down to maintain the proper wire clearance to the drum.

I have heard that it could be a voltage inbalance?

Have you read the motor current during running in both directions? Does the motor drive a worm/brass nut? Is the system a few years old. If a brass nut they can wear to a saw-tooth type pattern which rides up the worm thread in one direction.

Yes i do have a reduction for it but it is not attached, I took it off of it to test the motor current and rpm's

Any clue?, this lenze drive appears to be dimensioned properly. bus voltage good also.

How are you reversing the motor? through the drive? reversing contactor?

What type of inverter is it, Motec Type or Vector type (Lenze)

Have you disconnected the motor from the load to establish the high amps and slow speed in reverse?

If you changed the motor, drive, encoder and cable, only the incoming power and mechanical load are still unchanged. I do believe you probably have a load issue.

You can hook the old drive, motor and encoder up using the old cable and "bench test it" to see if they run ok if you cannot disconnect the load.

If all else fails, you might have to check them muffler bearings.

Well they found that the encoder was out of phase, It has an a+ and a A- wires that have to be reversed when the phase of the motor is changed. It is a lenze 9300 series drive hooked to a Lenze 1.7 kw motor. they called lenze this morning to get the scoop on the encoder. thanks guys!!

Is there a mechanical brake on the motor not releasing for the reverse direction?

Now wait a minute here, guys! The original post says "an a/c motor connected to a d/c drive". Somehow I don't believe that the motor runs in either direction if this is true.

What I really suspect is happening here is that this is a d/c motor connected to a d/c drive. I'll bet the motor is a compound wound motor as in having a series as well as shunt field.

Note that the poster said if he reverses the A1 and A2 leads the motor reverses. What a/c motor ever had A1 and A2 leads?

The important thing about compound wound motors is that they are not symetrical as to torque. The two fields add in the forward direction and subtract in the reverse direction so---lots of torque forward and very little in reverse.

Generally speaking, compound wound motors are not to be used on machines loaded in both directions.

Check the motor nameplate. I'll bet it says "comp shunt" or "stab shunt" on it. That's a compound wound DC motor.

The Lenze 9300 is an AC Frequency Invertor

The reversing of A1 and A2 i cannot see (might be the red wine) but i did see mention to reversing A+ A- on the encoder !!

I took the statements in general, an AC motor connected to a Lenze VFD which actually uses DC voltage to produce an AC output waveform (voltage).

I also assumed he meant A and NOT A, not A+ and A minus; which also does not make sense in general. If using 2 directions you can use just one part of an encoder but it is better if you use A and B with B, or the relationship of A to B, providing direction.

Note: The encoder may go bad and provide improper signals BUT it cannot just be out of phase, you never have to change the wiring for an encoder; the receiving device translates the signals as needed.

The gist of the last 2 posts hotrod; properly explain what is happening using proper terminology.