Quote Originally Posted by JAZZCNC View Post
No instead about it they are completly different things.! . . . Circuit breaker is a type of Fuse where a contactor is a Switch they do different jobs. Both are needed.
What I think your meaning is can you get away without the Contactor and use general pupose Relay Contact of the Pilz relay instead.? The answer is yes but not recommended for high surge devices like VFD or Toroidal transformers. Few reasons really.
Pilz relays are not cheap and over time those high intial surges will take there toll on the contacts and if for some reason say the transformer shorted internally then has wears it could melt the relay contacts before the Circuit breaker tripped.!
Using a contactor for high surge devices lowers the stress on the expensive safety relay contacts because your only passing low current thru them to turn on the Contactor Coils.

The Master safety relay which is what your Pilz will essentialy be shouldn't connect directly to any high power device it's function is to monitor lower voltage safety circuits IE 24V E-stop , guards etc before allowing a reset. Then turn off any contactors or Relays if any of those safety systems fail using low voltage.
Only the Contactors or relays suitably sized should directly power devices.

Now in your case if you don't want to buy Contactor and are prepared to risk the expensive Pilz then yes it will work without contactor going directly thru the relay contacts but you will lower it's life.

If you really don't want to risk the Pilz relay then you could use a Normal relay with suitable size contacts for the high power devices but Contactor is the correct way and won't cost much more money.! . . . Certainly much cheaper than a Pilz relay.!!

Oh and by the way I forgot to explain why it's not a good idea to use the Cslabs circuit of killing power to the controller.? It drops the ethernet signal to Mach3 and the plug-in will time out meaning a reset of Mach3 which is a royal pain in the arse.!
Sorry what I meant is, why do we need to use the contactor switch instead of just direct connection to power source, is it the same purpose as having a mechanical switch for example? can I just use a disconnect switch and be done with it?

I definitely will get one but all I find is ones controlled with AC voltage, I read that I can make them work with DC though