3 Phase Motor Overload Problem?

[gerard]

A conveyor system at work is powered by a 3-Phase Motor. It's a simple setup really. It is DOL start/stop
system with a telemechanique thermal overload. The problem is, when the conveyor becomes jammed-which is regularly does the overload does not cut out fast enough to prevent damage to one of the many drive shafts
on the system. So my question is - Is there an Electronic/Electrical or any other method of cutting the motor
more quickly and preventing this problem?

 

[adnarim]

Assuming that you have the correct overload and setting for the FLC of the motor,you could fit a slipping clutch coupling with a proximity switch fitted to it ,to indicate jam up.
The clutch can be set up to release at a certain torque to prevent damage,hope this helps

 

[gerard]

Thanks for your reply. The settings on the overload are fine.
Ok that sounds like a good idea. Have you any idea where I could get some information on
a slipping clutch and is it difficult to install?

 

[adnarim]

Sorry i don,t have any info,but search around on the net, i am sure you will find info,most machines i have worked on came with them fitted,or try RS Components or similar.

 

[stef]

Hi there,

we had similar problems at work and then decided to fit a PowerFlex inverter with torque limiting.
No problems since . . .
A bit pricy though

 

[SirKit Breaker]

The root cause of your problem would appear to be the conveyor jamming. Why cant this problem be addressed, instead of trying to engineer out another problem by installing extra bits and bats?

 

[gerard]

Thanks guys,
The conveyor runs well for the most part but becanse of the nature of the product
it is impossible to prevent the jam up when it does occur- unless you sit and look at it all day- and
then it would never happen!!
I have 2 good potential solutions to my problem:-
(1) Install a slip clutch
(2) Install an Inverter with torque limiting
I will look into these and see which I think is the best suited .

Much obliged!

 

[Quadrant]

A conveyor system at work is powered by a 3-Phase Motor. It's a simple setup really. It is DOL start/stop
system with a telemechanique thermal overload. The problem is, when the conveyor becomes jammed-which is regularly does the overload does not cut out fast enough to prevent damage to one of the many drive shafts
on the system. So my question is - Is there an Electronic/Electrical or any other method of cutting the motor
more quickly and preventing this problem?

Hi Gerard
You get programable electronic overloads where you can set o/l window,but the best would be to get your client to change to VSD control(every electrical fault feature is covered by a mere perameter setting)
Regards Roy

 

[Wazzajnr]

I would go down the inverter route myself. Most inverters have digital i/o and some basic programming ability. You could even set it to set off a siren at a certain torque just above normal running and then a stop somewhere slightlky above this.
That may allow the jam to be cleared before it gets too entwined in the rollers thus minimising downtime.
I find Parker SSD 690+ drives a good drive with free programming software. Also Control techniques are good as they allow ladder programming within the drive but these tend to be more expensive

 

[Griffin]

I agree with Sir Kitt, fix the route cause of the problem the jamming. If this cannot be sorted maybe a couple of photoelectric sensors maybe to detect when boxes jam and drop out the control circuit to the contactor.

A