Hi All,

We have one 15HP AB Power Flex 700 AC drive which is driving a roller which is in contact with another roller which is driven by another motor. Current speed is set to 50Hz and system is drawing 8 amps. The problem is when ever the speed is increased drive trips in Over Voltage. Deceleration time is set to 20sec. Drive is using encoder feedback. We tried open loop as well but same problem. Also we performed dynamic and static self tuning and both passed.

Any idea to solve the issue is highly appreciated.

Thanks & regards,

Shree

 

Are you using dynamic braking, chopper? if not try to use one.

 

It sounds like your rolls are turning at different speeds. the motor is generating voltage back onto the drive bus.

 

Shree,

There are a couple power related things you may not have considered:
Is the power system ungrounded?
Does the drive have line reactors connected ahead of the drive?

Ungrounded power systems are susceptible to instantaneous voltage changes and you can get over voltage and under voltage at the same time on different phases.

Line reactors drop voltage as they conduct current even during re-gen. For example a 460 volt drive with line reactors powered from 480 volts. The drive will have an over voltage fault when regenerating as the voltage at the drive will be 480 volts plus the voltage drop across the line reactors.

This problem has been addressed and solved not by operating in re-gen but it has been solved by using a dynamic breaking resistor to dissipate the energy.

I hope this helps,

William Hinton

 

Hi,

We managed to fix it by changing Parameter 153 - Regen Power Limit from -50% to 0%. Now we have reached 80Hz (maximum speed required by the machine) without any problem.

Can anybody explain changing of parameter 153 how helped to solve the problem?

Thanks for all help.

Regards,
Shree

 

regen = regenerative i.e. how much you allow it to draw energy from the motor.

as previously stated by other posters... the motor at question was being driven by the roll it is in contact with i.e. the other motor...

you made it so this motor is now along for the ride and probably doesn't do anything. disconnect the motor and take it off the machine... sounds like you don't need it... you've effectively handcuffed it and it isn't doing anything but spinning along for the ride