SSR switching of 240vac element

Discussion in 'General Electronics Chat' started by ed1966ss, Mar 25, 2008.

  1. ed1966ss

    Thread Starter New Member

    Mar 25, 2008
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    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
     
  2. KMoffett

    AAC Fanatic!

    Dec 19, 2007
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    What type of PID output: ON-OFF, PWM, or Phase control?

    Ken
     
  3. ed1966ss

    Thread Starter New Member

    Mar 25, 2008
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    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.
     
  4. KMoffett

    AAC Fanatic!

    Dec 19, 2007
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    Zero-crossing SSR will work fine.

    ken
     
  5. Pich

    Active Member

    Mar 11, 2008
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    The ssr will see the full 240 v when in the off position therefore it need to be rated for 240v ac.
     
  6. ed1966ss

    Thread Starter New Member

    Mar 25, 2008
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    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?
     
  7. Pich

    Active Member

    Mar 11, 2008
    119
    4
    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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