Solid State Relay: 12VDC when rated for AC?

[ntsqd]

I have been given some industrial SSR's. 6-32 VDC triggers them, but the power 'contacts' are rated for 50 amps at 120-240 VAC.

Best to assume that 50 amps is all that should be switched, even at 12 VDC?

Or can I base max 12 VDC amps on watts calc'd from the ratings with a ~25-30% reduction to account for the difference (cooling time) in current flow?

I don't have a specific application for these SSR's, I just want to know what I can plan on being safe & reliable for them to switch.

 

[Rando]

Unfortunately these most likely won't work for switching DC loads. Most AC SSRs use a silicon controlled rectifier (or TRIAC) to switch the load side, which will only work with AC. If you have the model number I am sure you can find a spec sheet that should reveal all.

I have been given some industrial SSR's. 6-32 VDC triggers them, but the power 'contacts' are rated for 50 amps at 120-240 VAC.

Best to assume that 50 amps is all that should be switched, even at 12 VDC?

Or can I base max 12 VDC amps on watts calc'd from the ratings with a ~25-30% reduction to account for the difference (cooling time) in current flow?

I don't have a specific application for these SSR's, I just want to know what I can plan on being safe & reliable for them to switch.

 

[ntsqd]

Well that would sure be a bummer. I was looking forward to the robustness & MTBF rating of these relays. They're at home and I'm at work. I'll have to try to look at them this evening.

 

[DaveInDenver]

If it's a thyristor type SSR, then Rando is correct, but the SCR type SSRs can work on DC. The unfortunate part is Rando's point that it's unlikely that the same SSR will work for both DC and AC. The problem would be that if it's designed for AC it is very likely to be a triac type, which means that with a DC load the triac would latch on until you killed the power and be pretty useless for a controlled relay. Best advise is like Rando says, stick the part number into the The Googles and see what it says.