[Shop-talk] Two SSRs from one PID controller

[DAVID MASSEY]

 Since the minimum voltage required to turn the relays on is 3 volts wiring them in series will work also.  If they are the same model relay they should share the voltage and, by definition, receive the same current and they will both turn on.
Either configuration, series or parallel, will work provided the parallel configuration doesn't require more current than the controller can provide.
 
Dave 

 
 
-----Original Message-----
From: Mark Miller <markmiller at threeboysfarm.com>
To: shop-talk at autox.team.net
Sent: Sat, Oct 3, 2020 1:55 am
Subject: Re: [Shop-talk] Two SSRs from one PID controller

Short answer: yes, you can run them successfully in parallel. The PID 
relay control output puts out 12V at up to 30mA.  The relays turn on 
with a minimum of 3V (max 32V) applied, and at a low current.  So 12V is 
good (more than 3, less than 32), and the only issue is if 30mA, or 15mA 
per relay, is enough to trigger it. And it is.  This particular one does 
not spec the current to turn on but I looked at one from a 'real' 
supplier (Omega) and they spec a max of 14mA (and it's only that high 
because there is an LED in their relay showing that it is on).  Think 
about plugging two lamps into a wall outlet: it's fine as long as you do 
not draw too many amps - you have 15 or 20A max.  2 lights? OK (less 
than an amp each).  2 toaster ovens? Not so good (12-14 amps each). 
These are more lampish.  The output of the relays are where the large 
power will be controlled (which is why you use the relays).

Regards,

Mark Miller  707-490-5834
markmiller at threeboysfarm.com

On 10/2/2020 11:00 AM, shop-talk-request at autox.team.net wrote:
>> On Thu, Oct 1, 2020 at 7:10 PM <lee at automate-it.com> wrote:
>> I want to operate two solid-state relays simultaneously (one for a 110V circuit, the other for 220V) from a single PID. I had thought I would just wire them in parallel from the PID, but a bit of poking around the interwebs suggests otherwise. So I sketched up this drawing for two SSRs in series with a PID. Does this look correct for this situation? Any suggestions appreciated!
>>
>> (I'm a chemist, so I understand electron flow and related, but I trust this little Shop Talk community more than I trust my electrical intuition!)
>> Thanks!!!
>>  Lee
>>
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