Just how hot does a SSR get?

[Loetz]

I've started to build my control box, and I'm happy with the way it's coming together, but I am a little worried about the heat from the SSR.

Take a look at this picture of what I have so far...

I had to cut out the holes for the SSRs so that they would fit, but they are still touching the plastic around them. Is that going to be ok or will this cause problems?

Also I'm planning on putting a sheet of plexiglass across the middle when I'm done with it, but the tops of SSRs will only be around 1mm away from touching the plexiglass. Maybe even less than that. Is this going to cause a problem?

Both SSRs have heat sinks and are attached to a metal rail.

 

[screamlead]

Not sure about anyone else but i would have mounted them the other way round with the heat sinks on the outside. Unless you stick a fan on the inside to blow out the hot air or suck in cold??

 

[Aleman]

Definitely heat sinks on the outside . . . and as long as the SSR base contacts the heat sink base there should be no issue with heat transfer.

 

[MankySteve]

Your going to have main voltage live contacts exposed with your current set up. So yeah as other have said heat sinks up.

 

[Mark1964]

we have the heat sinks on the inside of the box and have heated up water in our hlt from cold. Yes they get hot but not wire melting hot i wouldnt worry about where you have them now. Just go ahead as you have them will be no problem the ssrs really need to be on the inside as do the heat sinks

 

[Loetz]

You guys are probably right about mounting the heat sinks outside of the box, but I'm not sure how I would do that with this box at this point. And I like having the heat sinks attached to the metal rail on the back of the box anyway. I'll probably just have to install a fan. The 2nd hand electronics shop across the street from me has a whole box of old computer fans for almost free.

I want to use the top half of the box for mains in and out and the three XLR connections.

I've read around that I should install fuses in the box. Is that true? What fuse would I use?

The plan is to be able to set the box on a table like this or mount it on a wall.

 

[Mark1964]

wouldnt leave the ssrs there they will be live and risk electric shock its your choice but as i said our solid state relays and heat sinks are inside the box and get warm but not very hot

 

[Loetz]

wouldnt leave the ssrs there they will be live and risk electric shock its your choice but as i said our solid state relays and heat sinks are inside the box and get warm but not very hot

Oh, I'm planning on putting a sheet of plexiglass over the middle of the box. The SSRs won't be exposed.

 

[Swift Pint]

I dont know what others experience is, but I've got a couple of really small heat sinks from RAM on my SSR, and they seem absolutely fine & hardly get hot at all. I dont think you need to go OTT on heatsinks / cooling. What does everyone else reckon?

 

[keith1664]

I have 2 SSR's on heatsinks inside a metal box with a few holes drilled in it, no fan and it doesn't even get warm.

 

[evanvine]

I ran my first PID/SSR without a heat, it melted the plastic of the SSR!
You MUST insulate those exposed SSR terminals, if not, you have an accident (fatal?) waiting to happen.

 

[Loetz]

I dont know how many times I can type that I'm putting plexiglass over the SSRs.

 

[evanvine]

I dont know how many times I can type that I'm putting plexiglass over the SSRs.

At least 10 more!

 

[Loetz]

:

 

[BigYin]

I have my SSR's mounted so the heat plate is clear of the sidewall of the box they are housed in, and an old fan from a pc drives air passed the plates, and that air exits from numerous holes in the box beyond the SSR's.

It works a treat, and the SSR's never get hot.

So, either heat sink as others have done, or fan. Don't really need both heat sinks AND fan, but you DO need one or the other.

Apart from the risk of damaging the SSR, actually the performance of the SSR degrades as it warms up, so the amount of current it allows through to the heating element reduces. Best avoided!

 

[Loetz]

I've read around that I should install fuses in the box. Is that true? What fuse would I use?

So, I still don't know what to do about the fuses. Each of the SSRs will be connected to their own mains which are serviced by 15a fuses.

Do I need to have another fuse in the box? I've seen some posts about putting a 1a fuse in the box, but I don't understand where or why.

The hope is to have the brewery together for Easter!

 

[evanvine]

Do I need to have another fuse in the box? I've seen some posts about putting a 1a fuse in the box, but I don't understand where or why.

I think the other fuse you are refering would be for the PID power supply.
To make any sense this would need to be circa 10mA

 

[Loetz]

Is this something that is seriously needed?

 

[evanvine]

Is this something that is seriously needed?

Not really!
But you did ask.