Home Forums General Discussion Technical Questions miprom 21 ME81 fault

friend has been having intermittent Hard faults on a miprom 21 with digital dc drive. he called me today while he was at the job, with the car stuck, after checking motion excuses, the error was no retries left 23. 23 indicated Hard fault.
i had him check the Hard fault led on the main board, and look for the f1-16 code, but nothing was on. then had him look at the service log, only 2 errors 23 and 13. and only error in the drive error was ME81 excess rotation. tried to resume operation, but the 23 error came back, and car would not run. reset the power and car ran again. this seems strange, it was a hf but no led was latched, and the me81 excess rotation error, seems to be an error that would be generated if the car was an ac drive, and had the load weighing cell connected to the disc brake. seems like a strange problem, he indicates that it has been going on since they replaced one of the motor fields. any one see anything like this before? doesn't the HF led stay latched once a car gets a hard fault? could it possibly have something to do with the balance complete circuit? any ideas

an ME81 is excess motor rotation. If it happens,and the car was at or near floor level, it most likely occurs during current ramp down. the drive holds the car in place until the brake sets. In this case the motor field current may have changed from when the car was setup, causing the car to pull through the brake, or the drive isn't strong enough to hold the car until the brake sets. Another thing he should check is the coupling on the position encoder, if it happens some where else in the hoist way.

Is the brake setting too soon or not soon enough? Make sure the M contactor isn't hanging up. Look at 560, 561 & 566...

Replace both brake relays on board (black relays),relay bad.

Was this problem ever corrected?

Are you speaking of the actual motor or the settings in the drive? If it's the motor itself would an autotune correct this issue?

The field current is a programmable parameter that varies depending on the motor size,speed ,capacity, etc. The motor nameplate will give you some information. The Autotune is used to tune the armature. If in fact you can get the Autotune function to work. You had to remove the choke coil and the capacitor-resisters from the Armature loop and then try an Autotune. Later models worked better than earlier ones.

A bit more info on Autotune. It is used in Mods where the Motor Specs aren't readily available. The fields are energized and the motor Armature is is held at zero speed. When the M switch is pulled in for a second or two, no Motor rotation should occur. The Inductance of the Motor is then measured. Using these measurements changes are made to various Drive Parameters. As I said in the previous post. It worked better in theory, than in real life.