Solid State Relay HEATSINK

Discussion in 'General Electronics Chat' started by Dritech, Sep 18, 2015.

  1. Dritech

    Thread Starter Well-Known Member

    Sep 21, 2011
    756
    5
    Hi all,

    I am planning ti use a SSR to turn on an appliance which consumes 1100W at 240V.
    The appliance will be turned on for about 1.5 hours each day.
    The SSR is an OMRON G3NA-240B 40A 200-240V.
    Is it possible to use the SSR for this application without a heatsink?
     
  2. bertus

    Administrator

    Apr 5, 2008
    15,646
    2,345
    Hello,

    Did you read the datasheet?
    That says that the 240B can work with 0.1 to 6 A without a heatsink:

    Omron_SSR_ratings.jpg

    Bertus
     
    Dritech likes this.
  3. Alec_t

    AAC Fanatic!

    Sep 17, 2013
    5,779
    1,103
    I'm surprised. The triac in the SSR will drop about 1.6Vrms, at a current of ~4.6A, so will dissipate ~ 7.3W. I would have expected that to require a substantial heatsink. But if the manufacturer says it's ok ......
     
  4. Dritech

    Thread Starter Well-Known Member

    Sep 21, 2011
    756
    5
    EH I missed that part. Thanks for the reply.

    I will be using the SSR with a timer to turn off the supply of an ironing machine after a pre-set time.Is there something I must be concerned about?

    Also, the ironing machine consumes 1100W at 240VAC. That makes it consume about 5A right? so no heatsink will be required.
     
  5. AnalogKid

    Distinguished Member

    Aug 1, 2013
    4,520
    1,247
    Correct, but that assumes that the relay is mounted in free air. If it is in an enclosure of any kind, long term reliability will decrease.

    That is a full size SSR package with a large heat conducting surface on the bottom. An acceptable heatsink would be just bolting it to something metallic that normally is cooler than the relay is when operating.

    ak
     
  6. #12

    Expert

    Nov 30, 2010
    16,261
    6,768
    What AK said.
    It depends on the size of the case.
    Seven&1/3 watts with a radiating surface of 4.5" x 2.28" x 1" (approximately).
    Over 10 square inches per face (Not including the 1 inch sides).
    Think for a moment.
    That's a lot more radiating surface than a 10 watt resistor.
     
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