Do I need to use an SSR?


 

Dave Rogers

New member
I’ve bought an Inkbird ITC-106VH PID controller with the intention of building my own ATC.
The PID uses 110vAC and I will using a 12vDC fan. The output from my PID is 12vDC.
My question is should I use the PID output to switch the input SSR and have my 12vDC wired through the output, or am I ok to hook up my fan directly to the PID output?
The only negative I can think is that the fan will be drawing all its power straight from/through the PID whereas if I use the PID to switch the SSR all the power for the fan will be coming from its own 12vDC plug in power supply?
Anyone have any input?
Thanks
 
I’ve bought an Inkbird ITC-106VH PID controller with the intention of building my own ATC.
The PID uses 110vAC and I will using a 12vDC fan. The output from my PID is 12vDC.
My question is should I use the PID output to switch the input SSR and have my 12vDC wired through the output, or am I ok to hook up my fan directly to the PID output?
The only negative I can think is that the fan will be drawing all its power straight from/through the PID whereas if I use the PID to switch the SSR all the power for the fan will be coming from its own 12vDC plug in power supply?
Anyone have any input?
Thanks



Yep.

Check your specs, the 12v output for driving SSR is only 30 ma. Its a voltage signal.

You want a ssr with dc load
 
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I thought the output side of the SSR was just normally open contacts that close when the input is energized. It seems that is not the case so I cannot wire my 12vDC through the output as I planned.
I’m thinking I will have to have a 110v receptacle controlled from the output of the SSR and have my 12vDC power supply plugged into that.
Or just get a different relay, with a 12vDC coil and I can run my 12vDC fan power through the normally open output contacts as I originally thought.
 
I thought the output side of the SSR was just normally open contacts that close when the input is energized. It seems that is not the case so I cannot wire my 12vDC through the output as I planned.
I’m thinking I will have to have a 110v receptacle controlled from the output of the SSR and have my 12vDC power supply plugged into that.
Or just get a different relay, with a 12vDC coil and I can run my 12vDC fan power through the normally open output contacts as I originally thought.

It is normally open, just a Solid State Relay.
But you must have a dc ssr.

Output of controller is some form of Pulse Width Modulation
The fast SSR (ssr is a relay) will do same the input does. (a mechanical. Relay cannot do this many times /sec, its not fast enough. The ssr can switch hundred times /sec without wear)

pwm basically changes the average voltage the motor sees, and controls motor speed this way. It may work very poor at low. Output%, but the fan is useless at low % anyway. (Fan flow will be proportional to square of output).

Simply wire the dc. Load ssr. Into one side of the motor power to switch the circuit on-off. In a high frequency control, This will happen many times/sec as approach 100%, at which point it just. Stays on. This works better for resistance heating than driving motor.


If a controller has analog output signal, instead of pwm, a speed controller might be needed.


Looks like Your controller has a control period to set from 0-4 sec. Default is 2.
At 10% output its on 0.2 sec and off 1.8
At 90% its on 1.8 and off. 0.2

You may need a diode across the motor leads.

These periods are too long to effectively be Voltage control at low frequency. The blower will always start full speed, possibly blowing ash around. If the control period can be set very low, fractions of second, it would act more like voltage control, real pwm. Variable speed, not variable on-time.
 
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