[GreenKeys] Solid State Motor Control Relay

[Jordan Spencer Cunningham]

I've been using electromechanical reed relays (okay, I like the clicking sound) for motor control. I have been using knock-off Foteks like this for controlling the loop circuits, though, since the reed relays common on the market-- perhaps on any market-- can't handle such high DC voltages. I have a large loop power supply with multiple loops, and I didn't want all my machines' magnets to engage needlessly when the shared loop PSU fires up. Would that hurt them? No, but better for various reasons to keep a circuit dead when it's not actually in use.

I used to get my SSRs from www.folgertech.com, but it appears that they have gone dark sometime in the past few months. I saw a rumor they were moving locations and going to reopen in Florida, so maybe they'll come back online next year sometime. These SSRs were about $2.00 each over there for the 25-ampers.

$4 is actually pretty good-- last time I looked on eBay (around two years ago), the cheapest I could find was about $10.

While I agree that an SSR rated for 10 amps should be more than sufficient for motor control, these cheap knock-offs can't nearly handle what they claim they're rated for. You can probably count on 50% of the rated load-- not that I've tested them, just that I've done enough research and seen this from others who have torn them apart and tested them. So I expect you'd still be fine with the 10-amper, but it certainly wouldn't hurt to get something beefier if the price is right.

-
Jordan Spencer Cunningham
teletype.net | GreenKeys Search Engine: teletype.net/gksearch
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On Sun, Dec 27, 2020, at 10:11 AM, ad7i wrote:
> Thank you Jeff.
> 
> Paul
> 
> 
> On Sun, Dec 27, 2020 at 11:46 AM Jeffrey Angus <jdangus at att.net> wrote:
>> On 12/27/20 8:39 AM, ad7i wrote:
>> > But I'm wondering if SSRs, in general, would be suitable for a TTY motor.
>> I use them for both controlling series governed motors and auto start.
>> 
>> -- 
>> "I am a river to my people."
>> Jeff-1.0
>> WA6FWI
>> www.foxsmercantile.com
>> 
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