the most out of ssr's

[MrLights2000]

how can i get the most power out of my ssr's i want to put almost 1000 lights on 1 ssr seprated over 4 channels is this possible if so does anyone have any ideas of how to do this

thanks,

danyn smith

[random_rodder]

Depending on the specs of the SSR, you could have 1200 or so lights.
As I understand it, the COOP SSR's we use can handle 3 100 light strands per channel, and the SSR's have four channels...

Sure someone will correct me if I'm wrong...


Brian

[Dan Ross]

I just looked at 1 strand of 100ct mini's and it draws .34 amps, 3 strands per channel should not be a problem.

edit. this is provided you are using a coop SSR.

[jmelvin]

Wouldn't this all depend on what amp triac you are using. My design uses an 8 amp chip per channel. http://www.christmasinshirley.com/forum/viewtopic.php?t=237

[P. Short]

All of the posts are referring to loads of 1A or less. The limit of the SSR is usually more related to the amount of heatsinking than to the current limit of the triacs. Without any heat sink at all, the TO220-based SSR should be kept under 1-2A (regardless of the rating of the triac), because it will hit the internal temperature rating long before it hits the current rating.

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Phil

[A Marchini]

All of the posts are referring to loads of 1A or less. The limit of the SSR is usually more related to the amount of heatsinking than to the current limit of the triacs. Without any heat sink at all, the TO220-based SSR should be kept under 1-2A (regardless of the rating of the triac), because it will hit the internal temperature rating long before it hits the current rating.

--

Phil

Man, Phil, I think we need a Bot on this website to continually spit out this message. I wish I had a dollar every time you address this. I could take the family out to the new steak house and feed everyone filet mignon.

T.

[Macrosill]

Even if a good heatsink is installed their limiting factor would then be the trace sizes and fuse ratings on the ssr. 1 amp per channel is the safe limit Sean Bowf calculated when designing the board. I have pushed it a little harder on a channel or 2 but keep things usually no more than 1 amp per channel and 4 amps per ssr board.

[ErnieHorning]

When you run more current than your heatsink can get rid of, the TRIAC gets hot and it stays on and can’t be turned off electronically. This just causes it to get hotter until it either fries itself or smokes the board.

[Sean Bowf]

how can i get the most power out of my ssr's i want to put almost 1000 lights on 1 ssr seprated over 4 channels is this possible if so does anyone have any ideas of how to do this

thanks,

danyn smith

You are looking at 3.3amps spread over 4 channels if you are using the normal 100 count minis. Make sure this is what you have, and if so, there should not be a problem.

There are some out there that run the SSRs with no heat sinks. Personally I mount a heat sink on mine even though I try to keep to the 1 amp or less per channel rule.

The SSR PCB was designed to easily handle 1 amp per channel. So the PCB should not cause a problem if kept at or under this current.

Sean

[Wayne J]

You can pick up cheap heat sink material at a hardware store. I use 3/4" aluminum angle .050 thick. It is cheap insurance.

http://img525.imageshack.us/img525/4923/gluezf4.th.jpg (http://img525.imageshack.us/my.php?image=gluezf4.jpg)

[Macrosill]

This has been discussed in the past but I will bring up the point again. How much of a cooling effect will the heatsink have on the 4 triacs in a small enclosed space like the outlet box? After you add in the cabling and receptacles then essentially close off all air circulation by making the box raintight by placing a bag over it or whatever raintight method you use. I am not saying a heatsink is a waste but I just want to bring it up so someone does not get the idea of putting a heatsink on and then trying to push the triacs at a higher amperage because they fell the heatsink will cure the heat issues.

[scharbon]

Wayne,
Notice you used wooden dowels as spacers instead of nylon, ceramic, or some other non-conductive material. I thought wood had some conductive properties (especially if it gets damp). I guess you haven't had any problems with that or you woudn't be using it.

Am I wrong about wood being a conductor? Are you doing something to minimize the possibility of the spacers contacting the circuitry? Or is that not wood and my eyes are failing me? I am curious because I am about to start enclosing my SSRs in some containers and I have plenty of wooden dowel but no nylon. Might be able to save a trip to Home Depot!!!

Thanks,
Steve

[BillAd]

Wayne,

Last year I used oak wooden spaces to support a 595 PCB. The copper traces dissolved after about one week where the wood contacted the board, probably from the high concentration of tannin found in oak and the moisture in the air. I now cut my own spacers from 3/8 inch plastic pipe that is used for the water supply to refrigerator ice makers. This material is very inexpensive and can be cut to the length desired.

Bill

[Wayne J]

Yes, it is wood, and it is oak. So looks like I'm in for trouble if the solder mask doesn't protect things. :(

[Sean Bowf]

I started out with wood spacers under my PCBs too. So far (knock on wood...pun intended), I have not had a problem. I did start buying little plastic spacers from Lowes...mainly because it was easier, less work, and I am lazy... :D

Sean

[jstlucas]

This has been discussed in the past but I will bring up the point again. How much of a cooling effect will the heatsink have on the 4 triacs in a small enclosed space like the outlet box?

Yeah, but try to find the posts...I was wondering that myself today. In the northern hemisphere the lights are going to be on when the nights are cold and that will help a lot in keeping the triacs cold. Wrapping the outlet boxes will keep the heat in, but running 4 8-amp triacs at 1 amp each shouldn't heat the interiors much and since the lights are sequenced and not on continuously the heating should be less. Maybe this year I'll put a thermometer in an outlet box or two and see what temps they run at relative to ambient.

[ErnieHorning]

In the northern hemisphere the lights are going to be on when the nights are cold and that will help a lot in keeping the triacs cold.
Unless your heatsinks are on the outside of the box and you don’t put them in a bag, I doubt that you’ll find that the cold will make much difference. The cold will only delay the initial warm up. After that, the captivated air will act more like an insulator.

This is also part of the reason that light bulbs don’t get dimmer when it’s cold outside.

Wrapping the outlet boxes will keep the heat in, but running 4 8-amp triacs at 1 amp each shouldn't heat the interiors much ...
Somewhere around 1.2 amps is the maximum that a single TO220 transistor can dissipate enough heat in open air. With 4 in an enclosed box, they will mutually heat each other, so the total heat will be more than 4 times. If left on long enough, they will be put over the edge. In my experience, unless the current is grossly high, the TRIAC will stay on continuously at high temperature but will still function correctly again once it returns to normal temperature.

[grages]

In the northern hemisphere the lights are going to be on when the nights are cold and that will help a lot in keeping the triacs cold.
Unless your heatsinks are on the outside of the box and you don’t put them in a bag, I doubt that you’ll find that the cold will make much difference. The cold will only delay the initial warm up. After that, the captivated air will act more like an insulator.

This is also part of the reason that light bulbs don’t get dimmer when it’s cold outside.

Wrapping the outlet boxes will keep the heat in, but running 4 8-amp triacs at 1 amp each shouldn't heat the interiors much ...
Somewhere around 1.2 amps is the maximum that a single TO220 transistor can dissipate enough heat in open air. With 4 in an enclosed box, they will mutually heat each other, so the total heat will be more than 4 times. If left on long enough, they will be put over the edge. In my experience, unless the current is grossly high, the TRIAC will stay on continuously at high temperature but will still function correctly again once it returns to normal temperature.

Sounds like we need a Heat Pipe design to transfer the heat outside. :)

[bonuts]

Or maybe a liquid cooled heat exchanging system like that of harcore PC overclockers. We could have tubing running in our yard along with the other wires. :D

I once saw a computer built in a sealed plexiglass case filled with cooking oil (the oil is not conductive like water and disappated heat). Some brave soul should seal a SSR enclosure and fill it with cooking oil. report back to us. :)

EDIT: On second thought, I think the 110AC power supply was left out of that computer case.