Output Relay VS output voltage

[martyjhuebs]

Without getting too into the weeds on things, I bought a Inkbird ITC-106VH and burned out the components for the SSR. I bought a replacement and got ended up with a ITC-106RH. The controller is meant for my RIMS tube. Can someone please let me know how the Output Relay is different than the Output Voltage and why the output Relay won't work for a RIMS tube? I've attached the picture to help.

View attachment 1503448878764.jpg

 

[golfindia]

I think the RH has a mechanical relay, which is not good for controlling an SSR. The VH model has a solid state relay and should control an SSR fine. Can you describe how it was all connected? What amperage SSR were you using?

 

[martyjhuebs]

I havent connected the PID at all yet. My SSR is a 40 amp. I don't think the SSR is necessary with the Mechanical Relay but I'm not sure if it will work with the RIMS

 

[passedpawn]

The PID's relay contacts are rated for 3A. Your RIMS element will certainly use more than that (for example, a 1500W 120V element will use 1500/120 = 12.5 Amps). If you're connecting the element directly to the pid, that's why your first one burnt up and your second one will too. Don't do that!

The best thing to do is use the PID to control an external switch, such as an external SSR (sold state relay) or an external mechanical relay that can handle the amperage.

Mechanical relays are not good choices though. The PID is going to be switching it on and off a LOT, and the relay's contacts will get fouled soon with carbon from the inevitable arcing that happens on contact closure. SSR's don't suffer from this.

 

[golfindia]

Most SSRs need 3-30ish DC volts to drive them. A PID with just a relay in it won't drive it without some sort of external power supply. A PID with a DC output for an SSR is the best solution, like the VH model, which supplies 12v for an SSR.

 

[passedpawn]

Most SSRs need 3-30ish DC volts to drive them. A PID with just a relay in it won't drive it without some sort of external power supply. A PID with a DC output for an SSR is the best solution, like the VH model, which supplies 12v for an SSR.

No problem driving the SSR with a relay. But you're right, I didn't include enough info to get the job done. OP shouldn't go forward with that PID, so seemed needless.

To make it work, the relay would need some voltage (say, 5V) on one side of the contact.

 

[augiedoggy]

No problem driving the SSR with a relay. But you're right, I didn't include enough info to get the job done. OP shouldn't go forward with that PID, so seemed needless.

To make it work, the relay would need some voltage (say, 5V) on one side of the contact.

Well to be fair.. Driving the SSR with a mechanical relay will likely burn up and fuse the contacts in the relay like you mentioned earlier...

 

[ajdelange]

Can someone please let me know how the Output Relay is different than the Output Voltage

The VH is an active device. When it calls for heat 12 VDC appears between pins 8 and 6. When there is no heat demand the voltage across these pins is 0. The supply isn't very 'stiff' i.e. it is a logic signal designed to drive an SSR and while it probably would drive a small mechanical relay that's not what it is intended to do.

The VR is a passive device with a pair of 'dry' contacts. When there is a demand for heat the NO (normally open) contacts close and pin 7 is connected to pin 8. When there is no demand for heat pin 7 is connected to pin 6 through the NC (normally closed) contacts. The contacts are limited in the amount of current they can handle. The implications of this have been given in other posts.

 

[processhead]

Not that this is the best solution for you, but I have modified PID units with a relay output to directly operate the input of an SSR when that was the only type of PID I had available.

SSRs are optically isolated and high impedance inputs that present a very low load to the device that drives them

Most PID units use a DC voltage to activate the internal relay's coil.

I tapped into the PID control voltage that drives the internal relay coil and soldered in two conductors to extend the signal to outside of the PID. This is what drives the SSR input.

I think 12 volts DC is pretty typical for the control voltage on many of these PID units,