Reverse shredder

[marksparky]

Hi folks been asked by a customer is possible to wire his industrial shredder so that it could reverse as well as go forward? Due to it becoming jammed frequently, it a three phase and neutral supply and help much appreciated.

 

[stef]

Hi folks been asked by a customer is possible to wire his industrial shredder so that it could reverse as well as go forward? Due to it becoming jammed frequently, it a three phase and neutral supply and help much appreciated.

Hi markssparky,

I assume there is a contactor for the motor in it. You'll need a second contactor, wired with any two of the three phase swopped over, electrically interlocked with the original contactor. Add a selector switch
which selects one of the two contactors. If the circuit is star/delta then it is a bit more complicated as you need two star delta starters, one for forward, one for reverse.

Have you got a circuit diagram which you could post?

 

[ian.settle1]

Hi markssparky,

I assume there is a contactor for the motor in it. You'll need a second contactor, wired with any two of the three phase swopped over, electrically interlocked with the original contactor. Add a selector switch
which selects one of the two contactors. If the circuit is star/delta then it is a bit more complicated as you need two star delta starters, one for forward, one for reverse.

Have you got a circuit diagram which you could post?

And mechanically interlocked as well

 

[Darkwood]

I wire these alot and due to the motors stopping with material in them its very easy for them to trip on startup unfortunately it requires a bit of a complicated set-up, the machine should start in reverse to clear itself before going forward so just a timer controlled inverter signal or contactor control, then current monitoring for jamming during run cycle to self clear with auto reverse depending on material in the feed (conveyor or hopper) needs to stop during these reverse periods etc etc....... as you see things can soon get very complicated, plc control , duel channel safety relays due to the hazard nature and fully self diagnosing system should all negate the need for manual reverse.
Some or all may apply to your job but you also need to consider rundown time for motor to coast to stop and that the reverse isnt active until motor is stationary as the interlocks on a forward reverse contactor wouldnt stop you trying to run it backwards straight away after hitting stop button even though the motor was still near full speed but coasting down.
Please remember that if you install a reverse system its down to you to safety access the machine , avoid reverse signal on forward rundown etc etc and any mechanical or electrical issues that arise due to your inexperience may land on your lap, which can be expensive if dealing with 75kw motors like i do.
Sorry to seem harsh but having a drive shaft snap can cause high maintenance costs or even serious injury if not worse.

 

[Davey101]

I know nothing about shredders, but I would have thought that altering the wiring, saftey systems, or design of a piece of kit like this would be foolhardy at least, and perhaps criminal. Although it may cost a fortune, I should think he would be best speaking to the manufacturer, or at least someone familiar with the install and maintenance of shredders.

All IMHO of course

 

[marksparky]

cheers for the replies folks think il maybe pass this up would be a bit out of my depth i thinks dont have much experience with motors and the likes lol