SSR switching of 240vac element

Thread Starter

ed1966ss

Joined Mar 25, 2008
6
I built a powder coating oven that uses a pid controller and ssr to control the temperature via 240vac elements. I'm using an ssr with a computer heatsink and fan for cooling.

The question that has come up is if it is appropriate to use an ssr that does zero cross trigger switching to control a 240vac heating element. Obviously the ssr only switches one 120vac leg of the circuit, the other leg is directly connected to the other terminal of the element. Does this setup contribute to premature ssr failure? Thanks
 

Thread Starter

ed1966ss

Joined Mar 25, 2008
6
What type of PID output: ON-OFF, PWM, or Phase control?

Ken
It's a rather simple pid (TC-408) and the instruction manual doesn't clearly state, but I believe it uses on/off control. Nothing in the manual talks about the ability to control the ssr output contacts nor is there any mention of PWM or phase control capabilities. It simply outputs 8vdc to control an ssr.
 

Pich

Joined Mar 11, 2008
119
The ssr will see the full 240 v when in the off position therefore it need to be rated for 240v ac.
 

Thread Starter

ed1966ss

Joined Mar 25, 2008
6
The ssr will see the full 240 v when in the off position therefore it need to be rated for 240v ac.
The ssr output is rated to 380VAC. Why would the ssr contacts in the off position see 240V? Wouldn't the load contacts be open at this point?
 

Pich

Joined Mar 11, 2008
119
When they are open they see 240 volts potential, you are using the ssr to cotrol power to the heater right? The 380 v rated ssr will do fine but it need to be rated for AC
 
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