220v 3 phase Barrel Switch or Contactors (relays)

[Dan]

Folks

I am rebuilding my Norton tool grinder, this thing was originally wired 480v 3 phase with an Allen Bradley style RT- full voltage reversing starter.
My question is can I just throw a barrel switch on this thing or do I have to use a similar starting circuit?

Thanks in advance

 

[Tony Wells]

Really depends on the current draw, but I suspect you won't find a barrel switch heavy enough. I'd stay with the contactor setup. You'll need to change heaters and coils on the contactors you have, if you intend to use them rather than simply replace them.

 

[Dan]

Thanks Tony,

I used the wrong name.

The switch I was talking about is called a Drum Switch not barrel, I will check the HP rating on the motor tomorrow, hopfully one of these will work.

http://www.grainger.com/Grainger/ww...ch&Ntt=DRUM+SWITCH&N=0&sst=subset

 

[Tony Wells]

No problem, Dan. I knew that's what you meant. I hope you find a heavy enough switch. I would simplify things a bit. Is there another motor to control, such as a coolant pump?

 

[Dan]

Thanks Tony and David for your speedy replies ,

Tony,
no other motor, or pump. What are the heaters and coils for? Can I bypass them?

David,
Safety is always my highest priority, This 3 phase motor will run off my converter which has a power fail circuit built in so for momentary power losses it is not a concern. The relays are rated for 480 I have 220, I know low voltage turns them on, Maybe if I can use the original contactors and it's already wired so not too much to figure out. For space and simplification I would like to use a drum switch, less wires and mess. Will the drum switch work? Or could I damage the motor?

 

[Dan]

Here are pictures of the motor, it is a 1 HP motor.

 

[Tony Wells]

Dan,
the heaters typically found in a motor starter type contactor are for overload protection, and won't be correct for 220. The coils on the contactor are what actually moves the armature by becoming an electromagnet when energized by the low voltage. If the control transformer has multiple taps for the primary, and you can set it to 220, then the coils will be fine. If not, you may have to do something different.

You say the starter are rated for 480, but is that what the machine was actually running on before you acquired it? What is the motor set up for?

You won't damage the motor, but David's point is well taken as far as safety goes. Less shock hazard at the control, and a no restart feature that won't be there on a drum switch. You could look at a low current (cheap) drum switch, and use it to control the contactors of the push button station wiring is a mess, but it's not that difficult to wire, normally.

edit: a 1 hp motor is not a problem finding a reversing drum switch for. If you don't mind the risks described so far, then go for it. Tons of them in use on BP type mills all over the world.

 

[Dan]

Thanks guys!

I have the power protection on my phase converter so I have decided to go with the drum switch, It will be safe, easier for me to wire, smaller profile and more cost effective.

Thank you Dave and Tony for your input.

Best

Dan

 

[Dan]

The Drum switch works great !

Thanks again!