G120 overcurrent, trip on high torque

I have a customer using a G120 drive for a motor on a large chain driven conveyor. The conveyor itself is not large but the chain itself is fairly large. Recently the chain failed in a manner which a high current or high torque fault should have been triggered. No such faults were generated so the motor kept running causing considerable damage to the machine.

I have looked at the parameterization of the drive and, it seems, at least the overcurrent setting is correct. The motor is rated for 25.5A and p0640 = 38.25A. From what I understand if the current exceeds p0640 the drive should have produced a f07801 fault, stopping the motor. I cannot determine the the time delay, if any, before this fault would be generated.

I am having less fortune understanding is a high torque fault is inherent with the G120 drive. I see mentions of how torque is controlled, etc., a concept I do understand, but I am looking for parameters which generate a drive fault if a torque limit is exceeded. If no such parameters exist my plan is to create logic in TIA Portal to monitor the torque and stop the drive if the torque exceeds a high limit for some very short period of time.

Dean Nederveld

No such faults were generated so the motor kept running causing considerable damage to the machine.

 Hello,

• What does drive "alarm history" say?
• If there is nothing in alarm log. I am afraid that OFF1,2,3  was not triggered because of p0640 current/torque threshold was not.exceeded and motor kept running, as you said above.
  
• So, I think, after mech repair works, you need to pay attention to motor current by load as you usually have in production process. Take a look in Starter during production, notice them.I am almost certain that you don't use full rated power of motor.
  
• Then parameterize the limits.Add 10-15% to working values.
  
• If possible do real test or simulation.

But I don't consider that this way is reliable and efficient by various dynamic loads.

Find additional solution to get feedback from chain or chain wheel, etc.

Cheers

The incident occurred last year and the customer, unfortunately, has only just now informed me. No historical record is available to check, but it is reasonable to assume the p0640 value was not exceeded or else the drive would have stopped. I believe you have confirmed this is how the alarm functions when the p0640 value is exceeded.

The ability to trip the drive on torque is still a mystery to me.

Dean Nederveld

but it is reasonable to assume the p0640 value was not exceeded or else the drive would have stopped.

 It's common case when mech. parts were damaged due to parameters which was set automatically by Starter Wizard, which are supposed to protect motor itself, not mech parts. And in case of half current/torque by production run, when conveyer is blocked by some reasons you don't get threshold exceeding due to settings for motor protection from overcurrent, which can be higher than you need for damage prevention.

Here is a simple philosophy.

But I don't consider that this way (I mean set limits) is reliable and efficient by various dynamic loads.There should be initiate some activities like current/torque measurements by production load.

Also you can consider additional solution in order to get feedback from turning/moving parts, such as chain itself or chain wheel, etc.

Cheers

TechTeam

If you want to create a fault when the limit is exceeded, you can use the load monitoring function (see function diagram 8013 in list manual).

 Monitoring the load torque, briefly on screenshot.