Solid State Relays

Hey all! Sorry I haven't been on much in a long while, I have been extremely busy with work.

I have noticed the prices of SSR's have dropped significantly, and they're far cheaper than contactors. Has anyone here had any experience with them? I am thinking about using some to control the quartz lights on my truck as opposed to having to get out and manually turn the breakers on, but I'm afraid of one failing and putting 120 to my 12V electrical system and frying my entire electrical system.

Also, do they need any sort of special cooling? Can I just mount them in a standard steel junction box?

Here's what I'm talking about for those that don't know:
24V 380V 40A 250V SSR 40 Da Solid State Relay Module 3 32V DC to AC | eBay

The lights I am controlling are standard 750W halogen lights. (Like what would be used on a fire truck)

Thanks, guys. I appreciate all the help throughout the years.

 

You must be a rich man with all that work.

Most of those modules.... including the SSR-40 DA's...... use an optoisolator input. The high voltage is isolated thru that optical module.

Usually if it says TTL or CMOS compatible.... you're safe.

 

...and use a heat sink.
.

 

Hi, Justin.

I have a SS relay on the 1,500 watt heater in my whirlpool tub that is working just fine. On the other hand, the DC SSRs I tried on my riding lawnmower project were a dismal failure.

Size your SSRs to about double the expected load AND definitely install them on heat sinks, the bigger the better. Do some research as to the protection systems used with both inductive and resistive loads and follow the recommendations.

 

HA! Not really! But I have lots of cool tools!

That's what I wanted to hear! Maybe if I put the "coils" on a 1A fuse as redundant protection it would help too in the event of something fails. I don't want to put another IDM in this thing...

The ones I linked were marked for 40A. In theory I can run 3 lights per relay if I had to, which is good to know. I think the 1/4" thick panel aluminum the compartment is made of would make a great heat sink. I can just mount a 1900 box extension ring over them.

What are you finding? I'm only finding information on overcurrent protection.

One last thing, are they going to be able to take any voltage fluctuations from the generator? The system is only powered by the onboard generator.