30A Control Panel Schematic Feedback

[michaeltrego]

Hi all,

I have been researching all the great contributions from P-J, Kal and other builders in order to come up with a design for my 30A 5500W, single PID system. Here is my schematic. Will my smoke test be smoke free?

Thanks!

Mike

 

[mwill07]

what software did you use to make this? I'm working out something similar and am tired of drawing w/ powerpoint.

thanks!

 

[michaeltrego]

what software did you use to make this? I'm working out something similar and am tired of drawing w/ powerpoint.

thanks!

I tried a bunch of different open source tools (I'm on Linux), but settled on Dia. For me, it was the easiest at handling the routing of wiring. And it works on all major operating systems.

 

[mwill07]

I tried a bunch of different open source tools (I'm on Linux), but settled on Dia. For me, it was the easiest at handling the routing of wiring. And it works on all major operating systems.

well it looks great, will definitely help you lay out the box as well as think about the schematic.

I'm sorry I can't comment on the technical aspects, I'm an entry-level guy myself trying to lay out my control box too.

 

[clearwaterbrewer]

I think your wiring looks good, I would add a 30 A fuse/CB to each leg to protect SSR in case of internally shorted element (I saw the smoke 2x in a row!) if you already have one in the breaker box, you are good, but if it is 40 or 50, you are not...

may want to have some higher amperage pump fuses on hand, a pump may draw more than 2A at startup.. then again, it may not...

I would also go with 12x14-14x16 box myself...

Nice work!

 

[michaeltrego]

I think your wiring looks good, I would add a 30 A fuse/CB to each leg to protect SSR in case of internally shorted element (I saw the smoke 2x in a row!) if you already have one in the breaker box, you are good, but if it is 40 or 50, you are not...

may want to have some higher amperage pump fuses on hand, a pump may draw more than 2A at startup.. then again, it may not...

I would also go with 12x14-14x16 box myself...

Nice work!

Thanks clearwater - I had read that the SSRs can only effectively be protected by ultrafast semi-conductor fuses. Will a regular circuit breaker provide the protection? And great point on the pump startup amps - I'll see if I can get some guidance from March on that.

 

[clearwaterbrewer]

If you have a 40A SSR, a ~23A element, and a 25A CB, I think you are good, but I cannot guarantee that... I know I blew two without a CB, and none since with a 30A one...

I would think it would take a lot more than 46A to blow a 40A SSR that has a heat sink... ~46A is the current you would have if both elements were on... way less than a motor starting.... maybe a direct short of 240V would blow it, but that usually makes a big orange ball in your vision-space... I have made a lot of those..

 

[mwill07]

looks like you have heavy gauge wire going between the elements and the contactors, you probably should have heavy gauge wire between the contactors and the SSR.

also, there are two red lines coming out of pin 2 of the SSR, going to each contactor. Would you be better off taking that to a bus to distribute to the HLT and Boil contactor?

 

[michaeltrego]

If you have a 40A SSR, a ~23A element, and a 25A CB, I think you are good, but I cannot guarantee that... I know I blew two without a CB, and none since with a 30A one...

I would think it would take a lot more than 46A to blow a 40A SSR that has a heat sink... ~46A is the current you would have if both elements were on... way less than a motor starting.... maybe a direct short of 240V would blow it, but that usually makes a big orange ball in your vision-space... I have made a lot of those..

OK - thanks again clearwater - FYI, I will only be running one element at a time.

 

[michaeltrego]

looks like you have heavy gauge wire going between the elements and the contactors, you probably should have heavy gauge wire between the contactors and the SSR.

also, there are two red lines coming out of pin 2 of the SSR, going to each contactor. Would you be better off taking that to a bus to distribute to the HLT and Boil contactor?

You're right mwill - I should have 10awg feeding the contactors as well. Is there really a difference if the SSR output has two direct lines to the contactors vs. going through a block?

 

[mwill07]

You're right mwill - I should have 10awg feeding the contactors as well. Is there really a difference if the SSR output has two direct lines to the contactors vs. going through a block?

no idea. Just seems like the contact block is the right thing to do. I'm sure twisting the wires and bundling them in the SSR would work fine, but it would be a cludge job. A professional would go with a contact block, I think.