Pump Control Relay
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Got_Nailed
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You fry the computer card. The same as if it hits your network. Yes more can happen but that’s the normal.
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Of course, the computer isn't as pricey a resource as it used to be, but I'll still shut one off if there's lightning in the vicinity. Given the reasonable cost of standalone controllers, I'm not sure how a PC is superior. I chalk up a lot of the home automation interest to the "Because it's there." mindset. Which is okay by me.
Jadnashua
Retired Defense Industry Engineer xxx
A direct lightning strike will smoke nearly anything. If you want to protect from near misses, use a high capacity surge suppressor. For the relay cards, consider opto-isolators.
Bob
More dumb questions about relays spec. Are all relays designed to operate in both VAC and VDC for the coil and the contact voltage? For the 220V pump, I believe the startup surge current can be almost 30A. I presume, I have to select one that is rated for 30A and 240 V? Thanks
More dumb questions about relays spec. Are all relays designed to operate in both VAC and VDC for the coil and the contact voltage? For the 220V pump, I believe the startup surge current can be almost 30A. I presume, I have to select one that is rated for 30A and 240 V? Thanks
Bob NH
In the Trades
The coil is usually designed for AC or DC. That is not to say that a DC coil won't work on AC, or vice versa, but I can't tell you what the result would be. A 24 VDC coil might not work on 24 VAC, and a 24 VAC coil would probably overheat and might burn up on 24 VDC. That is because the coil has higher impedance (not just resistance) at 60 Hz than it does at DC. Most big suppliers (Grainger for example) sell relays with AC rated coils and relays with DC rated coils.garcanser said:
You must separate coil ratings and contact ratings. For starting a motor, pick a relay or contactor (a contactor is just a bigger relay, usually open frame) that is horsepower rated (that will be the contacts) at particular voltages.
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