SSR Recommendations

[missing_link]

Any recommendations on which SSR would work best?

I am assuming that any SSR running a 15 or 20 amp load is going to require a heatsink and a Fan?

Would a March pump also require a heat sink on the SSR?

Linc

[ECC]

We've had success with the Crydom SSRs. D2425 and D2440 have both been used in systems. The BCS-460 has 5VDC outputs, so the 3-32V DC inputs of the Crydom line of D24xx work very well. Also tested Crouzet Gordos G240D25.

If you read the manufacturer's datasheet for the SSRs, they derate the load current based on what type of heatsink in used. Datasheet for the Crydom SSR is attached.

So in a nutshell, if you're getting anywhere close to the maximum load current (25amps in a D2425), then a heatsink is definitely recommended. If not, then just attaching it to a metal enclosure will probably suffice. I don't know how to quantify the heat dissipation of a metal enclosure (like a dual gang junction box for instance). A pump will only pull a few amps max, but a heating element could max out an SSR easily, depending on the wattage.

I'm interested to hear real world applications. How do you mount your SSRs? What are they rated for, and what is the load (amps)? Do they get hot? Have you ever seen a failure?

[bsfixit]

FYI D2425 SSR's are easily available on a certain popular auction site. just search D245, They are NIB ,10 bucks.

[bsfixit]

I got my first set of SSR's today .. I am going to get the other set sometime next week and start putting things together. Including the linksys wireless bridge
link: http://www.linksys.com/servlet/Satellit ... 4692497433
I came to realized that this is the easiest way to connect the BCS remotely at the brewery.

[tarheels]

i'm a little confused about what SSR's to get. Am i looking for 25 amp DC output. like these http://cgi.ebay.com/CRYDOM-Solid-State- ... .m20.l1116

thanks for the help

[ECC]

Yes, they have been used successfully. The Crydom D2425 SSR that you point to has a 25 Amp AC output.

[tarheels]

so i need DC input and DC output, sorry if this is a stupid question.

[ECC]

It just depends on what you want to control. The SSR control input has to be DC, because the BCS-460 has 5V DC outputs. That's why the 3-32V DC input Crydom D2425's work well.

As far as the output of SSR, it depends on what you are trying to turn on. If its a 120V AC heating element / pump / etc, it needs to be AC. If you want to turn on a 24V DC valve, the SSR output needs to be compatible with DC.

Just think of the SSR as a switch. The BCS controls the switch with a DC signal. If you want to switch a 120V AC, you need an SSR that can handle 120V AC output.

[bsfixit]

If I used a transformer that put out say 24v DC it should still work on a SSR rated for AC output. right? I mean its just solid state relay.
It should not matter what you switch with it.. AC or DC.. someone correct me if I am wrong.. the only issue I could think of is resistance of the output side of the SSR
would greatly affect the DC throughput.. but if all you want to switch is DC a regular mechanical relay should do the job . AND is probably much cheaper than an AC output SSR.

[ECC]

It should not matter what you switch with it.. AC or DC.. someone correct me if I am wrong.. the only issue I could think of is resistance of the output side of the SSR

I'm not saying this won't work, but I know that they offer different SSR's with both AC and DC output. So that leads me to believe that it won't.
One thing that I thought was interesting when testing some SSRs.. I hooked up the DC control, and 120VAC to one leg of the output of the SSR, but nothing to the other. Then I tested with a multimeter while switching the SSR on and off with the BCS-460. It read 120VAC when it was ON and OFF. I thought something was broken, but it turns out that there is a minimum load, 40mA in the case of the D2425s. When I hooked up a pump to the SSR, it switched as expected.