Surging motor

[Amp David]

Spoke to a customer today who have a machine that print and die cuts boxes.

He says when its running , the motor tends to surge now and then.

What would cause this. The supply voltage is nice and stable and the units have their own TX

 

[Darkwood]

Need more info, are the motor's VSD controlled, A.C. or DC do they have closed loop speed control, what do you mean by surge....speed up? or trip through overload?
What exactly is the duty of the motor....?

Very vague David need alot more info before we proceed to look at likely causes

 

[Amp David]

It speeds up slightly then drops back to normal running speed.

I'm useless with this type of thing hence why I didn't get involved really, so thought i'd post to try and educate myself.

It will be the main drive motor of the machine so it AC and must have a speed controller as the machine can be speeded up or slowed down

 

[Jurasic Spark]

If its a servo motor with closed loop tacho speed control it might be worth having a look at the commutator on the tacho. Give it a spray with suitable cleaner and a good blow off with the compressed air line.

 

[Darkwood]

Without getting too deep it could be a number of things, and with your knowledge not been in this field i fear a long winded conversation without getting far or you not fully understanding us, ask them if they have a POT' to change the speed, if so these can intermittently cause issues and give false outputs but this would be accompanied by them reporting other symptoms like if work ok until you set it at so and so speed etc, it may be what is known as closed loop speed control where a device measures the speed of the product or motor and feeds the info back to a control drive which then give accurate speed control, all these systems could be working correctly and reacting to a torque increase for the load on the motor like a cracked bearing which appears quickly then dissapears, this could slow down the motor momentary and the drive compensates as the issues disappears thus overspeeding for a short moment..... too many variables and causes to give an answer to be honest and really would require a site visit.

 

[stef]

If the motor has a tacho fitted, check the coupling, maybe it is slipping, this can cause a speed surge. I had this a couple of times.

 

[vaughant]

Spoke to a customer today who have a machine that print and die cuts boxes.

He says when its running , the motor tends to surge now and then.

What would cause this. The supply voltage is nice and stable and the units have their own TX

Had this on an identical machine in the papermill,was a dodgy mitsubishi drive unit (230v 3 phase).

Stefs suggestion of a dodgy coupling is a good shout too,had that many times.