madmachinst
Stainless
- Joined
- Jan 15, 2007
- Location
- Central FL
Contactor sizing
OK so my question about the potential relay just occurred to me I can use the Supco APR5 with its basic SPST NC contact and make things work though a DPDT contactor. problem is How big can I get one of those? I figured out just 20 amps to keep the idler going on idle then say about 140 amps single phase to keep the machine running at its highest draw. If all this is going through the contactor, do they even have contactors that big. Or do I only need something big enough to switch the 20 amps and regarding all the rest of the amperage the contacts are already closed so no arcing at the higher amperages, then again maybe just resistance welding? I need the contactor to switch between the pony motor and idler on the potential relays command.
OK so my question about the potential relay just occurred to me I can use the Supco APR5 with its basic SPST NC contact and make things work though a DPDT contactor. problem is How big can I get one of those? I figured out just 20 amps to keep the idler going on idle then say about 140 amps single phase to keep the machine running at its highest draw. If all this is going through the contactor, do they even have contactors that big. Or do I only need something big enough to switch the 20 amps and regarding all the rest of the amperage the contacts are already closed so no arcing at the higher amperages, then again maybe just resistance welding? I need the contactor to switch between the pony motor and idler on the potential relays command.
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