PID and SSR wiring

[Jordan West]

Hi, I have a couple of the Inkbird ITC100VL PIDs

I have a question regarding the SSR output...I am hoping to use 2 PIDs to trigger 1 Solid State Relay..(one at a time)

My plan was to connect the 2 negatives together on the PID's and then send them to the negative trigger of the SSR and with the positives from the PID's going through an on/off/on N/O switch to select which PID to take temperatures from and control the SSR...

My question is will this be fine? Can I common up 2 negative outputs together without one PID harming the other?

Does the negative terminal have a permanent negative and just switch the positive? or does it switch both? Manual doesn't really help

TIA

 

[Hoddy]

Hi, I have a couple of the Inkbird ITC100VL PIDs

I have a question regarding the SSR output...I am hoping to use 2 PIDs to trigger 1 Solid State Relay..(one at a time)

My plan was to connect the 2 negatives together on the PID's and then send them to the negative trigger of the SSR and with the positives from the PID's going through an on/off/on N/O switch to select which PID to take temperatures from and control the SSR...

My question is will this be fine? Can I common up 2 negative outputs together without one PID harming the other?

Does the negative terminal have a permanent negative and just switch the positive? or does it switch both? Manual doesn't really help

TIA

In short no. You should ideally be switching between the two. Whatever it is you are doing, or hoping to do.
I assume your looking at some kind of two stage heating control. So ideally switch each other/disconnect them from each other is the recommenced way forward.
And obviously, if your not qualified. Get a qualified electrician to check all of your work before you put it to work.

 

[Jordan West]

I'm switching the positives.. Its to control the HLT element..so the HLT pid will control the HLT element to heat up to strike temp then I switch to the mash tun pid to control the HLT element which has the HERMS coil in.. I just need to know if the PIDs can be wired like that, or if I need to switch the positive AND negative to the SSR.. Thanks

 

[Buffers brewery]

Hi, I have a couple of the Inkbird ITC100VL PIDs

I have a question regarding the SSR output...I am hoping to use 2 PIDs to trigger 1 Solid State Relay..(one at a time)

My plan was to connect the 2 negatives together on the PID's and then send them to the negative trigger of the SSR and with the positives from the PID's going through an on/off/on N/O switch to select which PID to take temperatures from and control the SSR...

My question is will this be fine? Can I common up 2 negative outputs together without one PID harming the other?

Does the negative terminal have a permanent negative and just switch the positive? or does it switch both? Manual doesn't really help

TIA

Just had a look at the spec for the pid you’re using. They have a pulsed low voltage dc output designed to drive a SSR. The low voltage output is not common to each device. I would advise you therefore switch the pid outputs independently i.e. both positive and negative, using a double pole, double throw centre off switch rated at 1 amp (the output of your pid is 12vdc 30 mA if I’m looking at the right one). Be safe and if in doubt get a sparks or friendly electronics engineer to look it over. Cheers

 

[Jordan West]

Yea I got a DPDT toggle switch to switch both poles...figured there was no way that could go wrong..Dont worry, I work for electrical companies and have all the help I need on the High Voltage side of things...Thanks for your time

 

[Drunkula]

I don't see why a common negative wouldn't work here. I'd like to be shown why, though.

 

[Jordan West]

I dont think the negative is a permanent 0v on the outputs...so you may damage the device when the other PID goes negative??

 

[Jordan West]

Im doing this now

 

[Drunkula]

I dont think the negative is a permanent 0v on the outputs...so you may damage the device when the other PID goes negative??

Are you using the same power supply for both pids? And what's the mininum switching voltage for the SSR? I'll check the ones I've got in a sec. Mine are 3 to 32. You're safer with the double throw but for me I'd still try it. I might do it when I've got 10 minutes and meature if there's any difference in voltage between the negatives using the same power supply.

 

[Jordan West]

yes but the PSU is 24V and the output is 12V

 

[Buffers brewery]

I don't see why a common negative wouldn't work here. I'd like to be shown why, though.

The problem you’re faced with is you don’t know what’s inside the pid. I’m guessing as the output is pulsed low voltage dc the output switch is probably a darlington driver (pair of transistors). Normally, you’d position this kind of device at the bottom (negative) end of the load so you’re in effect switching the “negative” line and the positive output is connected directly to the load. So, if you common up the “negatives” both pid’s are in control.

 

[Jordan West]

i emailed Inkbird and they said I cant common the negatives but with no explanation so im going with the dpdt switch...cant go wrong

 

[Drunkula]

So, if you common up the “negatives” both pid’s are in control.

I was wondering if the 3v minimum of the SSR switching would soak that up. And I couldn't really test that as I've got the relay versions and I'm not desoldering the relays for laughs. I kinda want to.... must resist.

 

[CBBC]

Doing something similar, just put a diode in each +ve line.