We have a vertical axis motor in one of our machine which malfunctioned as mentioned below

1) While enabling the motor axis moved at high speed and collided on the the machine bed. We can see the errors appeared in the device as attached. What could be the reason for this? It looks like a error happened during enabling the motor.

The machine was in a  stable working condition for almost 2 years. 

The mechanical couplings of the axis are intact. 

Did any one faced this kind of issue earlier?

When we checked the reason for fault F7412 in the list manual, its mentioned that this fault will be activated incase of speeds greater than P1752.

What is the significance of P1752(Motor model changeOver  speed operation with encoder).

Is there any chance that the motor moves if a drive cliq cyclic data trasfer error occurs?(31885)

Angle commutation error.

Your motor has a resolver angle that is not matched by drive's setting. This hapens when an encoder is changed or in rare cases when the motor has a big crash and its inner resolver angle is shifted .

Basically when you enable the motor, the commutation angle is wrong and the drive cannot correctly maintain the motor in position.

Solution : you have to realign the motor angle by setting a couple of parameters in the Sinamics Expert List. Then your motor SHOULD work perfectly forever.

But don't try to enable it in these conditons or you will damage something

We recovered the axis and decoupled the motor from load. The motor is working as normal when we run it. We restarted the system ran the motor, its working fine.

What might have happened in that specific time?.

We couldn't able to figure out the reason for the behavior. Only errors we found was 7412 and 31885.

We were checking our internal logic to investigate on this issue. This incident happened when enabling the axis after an emergency press. Our emergency condition logic is as follows.

stopEmergencyCall  -> DisableAxis ->InfeedOff-> Contactor Off

We are using _stopEmergency() incase of emergency press

_stopEmergency(

axis := ZAxis //technology object

,stopDriveMode := STOP_WITH_MAXIMAL_DECELERATION

);

Operator release the emergency and went to enable the axis. Sequence is as follows

Contactor On->InfeedOn->enableAxis

Its during this enabling, we are suspecting the above incident has happened.

In _stopEmergency command help we found the below statement.

ThestopEmergencyCommand=ACTIVE status may last longer than the_disableAxis()command is active, so thestopEmergencyCommand=INACTIVE status should be checked explicitly before the enables are reset.

We are not sure whether the incident has anything to do with the above explanation!.

If a _move command comes while brake axis is getting enabled(axis enable command issued but brake is not open), is there any chance of the above scenario?

What do we need to check before issuing a _move or _pos command in logic?

Atlast we recereated the issue and the observation is as follows. During disabled state, if we issue a _move command axis setPosition(_to.basicMotion.Position) changes but the actual movement on the load doesnt happens. The actual difference between the setPosition and actual position keeps on increasing till the _move command is active. The moment the drive and motor got enabled the load tries to move to the setPosition with maximum speed.

Why this happens?  We are expecting that it wont move if the drive is disabled , but its not so. We are also expecting a following error if the setPosition and actual position deviation is too large. But that also didnt happen.

Did anyone had this experience earlier. How to avoid this?