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Heatbed SSR heatsink question.

arnoldstrife

New member
So I'm checking my math and ensuring I'm not missing something. So the Omron SSR Datasheet (https://assets.omron.com/m/453bbd7a38a218b5/original/G3NA-Series-Solid-State-Relay-Datasheet.pdf) and Voron build guide says the max AMP of the Omron G3A-210B-DC5 SSR is 4AMP without a heatsink. My Bed heater is a 750Watt Silicone AC Heater. I'm in US so 120Volts. so that's 6.25amps. Which means I should limit it to 60% bed heating power. to keep it under the 4amp limit.

I'm wondering then can't I add a heatsink to bring up the SSR to 10AMP limit (or 7amp because there's an asterisk that surface mounting causes a 30% derating of the load in the datasheet. I'm not sure what that means). I bought this one: https://www.amazon.com/YXQ-Heatsink-Solidstate-Aluminum-Cooler/dp/B01M8MIVJ7/ applied thermal paste and It looks better than the ones in the datasheet to meet the minimum requirements and I just need to run over 4amps for like a minute when it first heats up. Afterwards, it's comfortably between 10-30% load well within even the heatsinkless load.

So if my math is right, this should allow me to go full throttle and not limit the heat bed speed if I use this heatsink. I'm not sure if I'm missing any elements that I should be aware of or reading the datasheet wrong so I thought to double-check.
 
With a heatsink (and ideally also a fan cooling it) you can absolutely crank the PWM duty cycle of the SSR without problems.
 
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