System Power/E-Stop

Hi all. I'm working on wiring diagrams for my electric build. Before I get too deep into things I'd like to make sure I'm on the right track with my mains power switch/e-stop circuit. Below is a diagram of what I had in mind. Seems a little different from some of the other diagrams I've seen and I want to make sure I'm not missing anything. Thanks in advance for the feedback.

 

I do not believe it will work the way you want it to unless you use a specific E-Stop switch. To pick the contactor, 2POS/NO must be switched on. Then when you hit the E-Stop it will drop. What happens when you let go of the E-Stop. It will work if the E-Stop is a locking type switch and not a momentary contact switch.

 

That is a fine circuit. I assume because you indicate and E-stop you will in fact use an E-stop switch, in which case it is fine. The only issue I see is finding an affordable contactor, but you can always find things if you look hard enough.

 

Yes, the plan is to use an actual e-stop switch (AutomationDirect GCX1226-120L). Auber sells 40A 2 pole 120v coil contactors for $18, which isn't too bad. Since I'm only planning a 30A system (for now) a 40A contactor for mains should be fine.

 

The auber 40 amp contactor is rated for a 50 amp resistive load. In the typical electric brewery (if there is such a thing), most of the load is resistive. The only exception would be the pumps but they pull less than 1.5 amps each.

 

So what you're saying is a 40 amp contactor is more than enough?

 

If you have a 30 amp system, the 30 amp contactor would be sufficient. It is rated for a 40 amp resistive load so even this is slight overkill. There is a difference in the connectors between the 30 amp (screw clamp) and 40 amp (lug). If you think you might go bigger (50 amp) someday, you might as well spend the extra 3 or 4 dollars and get the 40 amp.

 

Search ebay as well for definite purpose contactor. You just need to know the number of poles (2), resistive amps (min=30), and coil voltage (120 vac). You can find great deals on industrial quality components, switches, SSRs, and PIDs if you do your homework and know what you are looking for. That said, shopping ebay can be time consuming and if you are buying other stuff from auber anyway, it may be simpler to just buy there.

 

Nice catch on the different connections. I had missed that.

 

I know what you mean about ebay being time consuming. I'm about done sourcing parts for the plumbing side of the new setup, just starting to put together my shopping lists for the control panel and related electrics.