We recently restarted an elevator that has not run in many years. We did get it to move and run full speed several times to get it ready for reinspected by the state. Thursday I moved the unit on car-top down to the first floor to examine something. Car ran fine down. When I proceeded up the elevator took off like a rocket. no control just like full speed on car-top inspection...No errors either on the drive. Thinking maybe an encoder error I replaced it with another car, same outcome...We have changed the Logic board,field board is new, gate firing board has been swapped. One funny thing is one time we tried unit without encoder connected car ran down controlled and full speed up just like my problem. We did check the encoder wiring from machine to drive that looks good too! Any one ever seen this or have an Idea?

You said the drive doesn't show a fault. Are you sure the fault is not clearing itself before you can get to the display. Try it from the machine room while you can watch the drive display. Also try performing a 998 test on the drive. It is much like the 997 self-tune test. It will test all the current loop feedback/ SCR firing type of stuff. I am curious if you are getting a 98 or 99 fault that clears before you get a look at the drive. Certain encoders were famous for having the B B-not channel backwards even though it was wired as marked. While I don't know why this would have changed itself, verify the encoder resolution set in the drive matches the actual encoder ie 1024/2500/10000.

Hey HalfPick, I wanted to let you know that Magnetek has pretty good technical support on the DSD 412 Drive. Their number is (800)236-1705. Good Luck!!!!

Thanks for the feed back. Well, I have talked to Magnetek and they are scratching their heads. CEC is also out of suggestions. It is going directly to a 98 fault no tach only in the up direction.As soon as the M contactor pulls in the car tries to overspeed and faults on the drive with a 98 and then resets! I ran the car down almost to the lower limits on cartop. When I tried to run up on cartop the car jumped violently....I thought the secondary sheave was coming down the hatch. I disconnected the motor encoder and turned it by hand watching the 600 input all is good. correct direction also. I don't have much room to run down...The car will also run slow speed down with no encoder and then runs out of control in the up just like my problem.

If I try a good running car without the encoder connected car runs a little bit then faults with a 98 error.Whats weird is this car was running full speed and was on inspection before with no problems. This is an older babbit bearing otis machine, I know the circle W machines don't drift very well!

If big gearless motor....
Check to see if the interpole are rocking and shorting out against a motor field connection. Very similar to what you're talking about as far as results. Only seen it once in 30 some odd years, but I wont forget it.

Halfpick
I have two old Westinghouse gealess machines with futura controllers. One of the units was over speeding and banging pretty bad. Magnetek and CEC scratched thier heads with me as well! We were getting no indication from the fault log to give us a clear direction.

What I found was the velocity (vel) and speed reference (sr) were off. The encoder appeared to be fine as well as yours! What I discovered was the encoder shaft had too much play. Not too much play clock- wise or ccw but in and out!

This play of the shaft moving in & out affected the optics inside the encoder. It was as if the elevator was trying to launch into orbit.

I recommend you take off the encoder off again and and check the play in & out. If it is sloppy replace it. The encoder on the other lift may work fine on that unit and not on this one. Best of luck!

I just remembered something else! When I would run the car on inspection and watch vel & sr the one that was behind would catch up to the other...

I hope this is a sign that I'm losing my mind first!

Another thing you could check is to temporarily set IVE to your leveling speed and see if the drive can track the speed.Try setting IVE = 5 and then watching the speed command vrs car velocity on the RVU or your Wizard screen. I had a similar problem a few years ago and it turned out to be the DSD power supply which apparently also provides the power to the encoder.

Thanks for the feedback...We'll be looking at it again tomorrow I'll let you guys know what we find!

Well we got it up and running again. We checked all the suggestions. Finally we just removed a drive from a working car. No more problem. It must be the SCR's, it's the only thing we didn't replace or swap from another drive...Not completely sure what happened, but that was it. 998 check didn't find it...I guess we'll have to pull the drive apart on the bench and give it a good look!

did you check to see if you had a leaking SCR? i have seen them leak voltage when the SCR is off which causes the drive to freak out. if you have more than .5V on the output its a leaking SCR.

If not mistaken you can look at Armature current feedback on the DSD412. If the car is NOT running I would expect to see NO armature current feedback. Not an 1/2 amp or so.

Did look at Arm. Feedback current, that was OK. We were going to get into SCR's, but decided to just change out drive. It really only takes about 20 minutes to swap out once labeled. Actually a good way to clean out drive and swap out fans.