Thanks for your reply,

As you rightly mentioned the drive is designed for 150% of current for 60sec,which is as our operational requirement.being a wagon tippler(twin wagon) the drive is designed for 150% loading for 45sec during the load tilting of wagon.

We were analysing the issue and following observation:

1.When encoder feedback is zero,then the drive is tripping with stall or blocked rotor fault.-- statement mentioned in manual is conflicting with our trends,can you please provide any logic description to stall or blocked rotor.

2.During failure follower motor current went upto 900A for 45msec,at the same time master has limited the current at 605A,as both machines are hard coupled and seeing the same load,as per my opinion current shoot is not due to load,else it has to be replicated in both machines.

3,We replaced motor module of follower machine and Did local trail and found still the current was shooted upto 900A for follower motor and speed was 0.however same time master was limiting the current at 605A.(immediately we stoped the machine to prevent failure).

4.After that we replaced encoder also for follower motor and trail taken and found current was normal and both machines are in sync and normal in operation.

We have the following queries in our mind:

1.Is there any possibility that current controller is not working properly,if encoder feedback is missing/malfunctioning (any parameter need to be alter to limit the current on this condition).

2.Is there any possbility that we can trip the drive with speed mismatch/encoder error fault in case of encoder failure.

As you mentioned drive was running from last 9 years and purchased on 2012.

can you please provide us any preventive maintenace replacement chart for all the componenets,so that we can preventively replace components to prevent failure.