a relay board to recommend

This relay board from eBay has very good quality, its opto isolated input driver IC makea it working really good directly from WebControl OPx.  We can not post the URL for this item. but its eBay item number is 310574415181, you can paste that into eBay item search and find it right away.
 
From a customer told us, he was using this relay board to drive load up to 30A for a long time without any problem.

CAI_Support said:

This relay board from eBay has very good quality, its opto isolated input driver IC makea it working really good directly from WebControl OPx.  We can not post the URL for this item. but its eBay item number is 310574415181, you can paste that into eBay item search and find it right away.
 
From a customer told us, he was using this relay board to drive load up to 30A for a long time without any problem.

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would be great having a silent potential free relay capable of switching DC and AC...

I've used a non-opto four relay board and an opto isolated single relay board. Both work fine but I don't have a lot of hours on either. All the eBay 5V modules seem to use the same 5V Songle relay rated at 10A AC 125/250V and 10A DC 30V. As often happens with Chinese electronics the documentation is little to nonexistent to outright wrong. So care is advised when hooking them up. For example on the isolated relay I used the silkscreen for Opto ground and relay power ground is reversed as was the Vcc/Gnd polarity on the eBay drawing showing how to connect the unit.  Some sellers include a schematic which is nice since some modules are active low and other active high control input. Depending on application that may be important. I used a 12V version of the relay (not module) to replace an SSR. The SSR snubber was causing problems with the CFL. It was passing enough current in the off state to cause the bulb to flash occasionally. Built up a little kludge board to mount it in the same footprint as the SSR it replaced.
 
Looking at PCB isolation and traces on my boards I would be very reluctant to use them on AC. 30A is 3X the rating of the relay and even at 10A I would be leery.  But at a $1-2 per channel they are a great deal if used with those caveats.
 
/tom

Would like to find a good relay to replace some ssr so i don't need heat sinks on the ssr, but must be rated AC  30A to use on wall socket

pittom said:

Would like to find a good relay to replace some ssr so i don't need heat sinks on the ssr, but must be rated AC  30A to use on wall socket

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Here is what high current relays looks like, these have 24V coils. Notice the size of the contacts, that is both for current carrying reasons and arc suppression when circuit is broken. Hard to believe poor little Songle is up to the task, but as I posted works it fine at lower current on both AC and DC.
 
http://www.allelectronics.com/make-a-store/item/rly-571/24-vdc-dpst-n.o.-30a-relay/1.html
http://www.mpja.com/DPST-NO-24VDC-Magnecraft-Contactor/productinfo/18955%20RL/
 
http://datasheet.octopart.com/PRD-11AY0-24-Tyco-Electronics-datasheet-11085422.pdf
 
Coils take a fair amount of power, one way to reduce steady state power consumption is to use a series resistor shunted with a cap. The cap supplies enough current to pull in and the resistor supplies hold current. 
 
/tom

Search on eBay with "JQX-62F relay", it will show a lot of 120A 120AC relays.  You may need use of little relay to switch the large relay's coil.

Nice,i can use a dc ssr to switch the  JQX-62F relay

My experience with Chinese 110V/220V DC and 12V/110V relays is that they have 10kOhm in open state...

I find that very difficult to understand. Can you provide more info? Assuming you are referring to an EMR the air gap is virtually infinite. I can't say I've used a huge number of these Chinese 5v and 12v relays but I've never experienced anything like that. As I've mentioned previously there may be a problem with creepage distance but that is not going to show up on a simple resistance test.
 
/tom

Tschmidt said:

I find that very difficult to understand. Can you provide more info? Assuming you are referring to an EMR the air gap is virtually infinite. I can't say I've used a huge number of these Chinese 5v and 12v relays but I've never experienced anything like that. As I've mentioned previously there may be a problem with creepage distance but that is not going to show up on a simple resistance test.

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I'm with you, Tom. I've used probably only 40 or 50, of 3 or 4 different types, and never experienced anything like that myself either.
The relay contacts are frequently shall I say "optomistically rated", but never had a leakage problem. Many times, the contacts might be rated for 240V AC, but the tracks on the PCB are far too close for 240V for my liking. Many of the boards invert (as previously described) but they've all functioned exactly as expected.

rossw said:

I'm with you, Tom. I've used probably only 40 or 50, of 3 or 4 different types, and never experienced anything like that myself either.
The relay contacts are frequently shall I say "optomistically rated", but never had a leakage problem. Many times, the contacts might be rated for 240V AC, but the tracks on the PCB are far too close for 240V for my liking. Many of the boards invert (as previously described) but they've all functioned exactly as expected.s

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sorry 10M open and 10k closed... and its not a 230 V AC version but dedicated dc

Efried said:

sorry 10M open and 10k closed... and its not a 230 V AC version but dedicated dc

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dedicated DC output will almost certainly be solid state, not electromechanical.
 
I would fully expect 10M or so "off".
I would expect 10K "closed" if you don't know how to measure it. (Hint: sticking your DMM across it in ohms mode is not going to tell you anything meaningful)

rossw said:

dedicated DC output will almost certainly be solid state, not electromechanical.
 
I would fully expect 10M or so "off".
I would expect 10K "closed" if you don't know how to measure it. (Hint: sticking your DMM across it in ohms mode is not going to tell you anything meaningful)

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yes indeed those are SSR, disregarding my measurements it does not work as potential free contact for my room thermostat
I may recommend the SSR from OMRON and PANASONIC having phototransistors, they are working well for that purpose (low or no DC current).
since they are not available at small quantities and at least the SMD needs some complicated procedures to fix, a ready to use piggy back solution would be fine...

Efried said:

yes indeed those are SSR, disregarding my measurements it does not work as potential free contact for my room thermostat
I may recommend the SSR from OMRON and PANASONIC which are working well for that purpose (low or no DC current).
since they are not available at small quantities and at least the SMD needs some complicated procedures, a ready to use piggy back solution would be fine...

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I'm not sure that any conventional SSR is appropriate for the application you want to use it in.
Optoisolator, sure. But not an SSR, which by its very nature is intended to switch a minimum current and a minimum voltage.
 
Why is it you always seem to be trying to shoe-horn the WRONG device into an application it wasn't intended and isn't suitable or appropriate for, and then blaming the thing that doesn't work rather than the person who mis-used the wrong part in the first place??

rossw said:

I'm not sure that any conventional SSR is appropriate for the application you want to use it in.
Optoisolator, sure. But not an SSR, which by its very nature is intended to switch a minimum current and a minimum voltage.
 
Why is it you always seem to be trying to shoe-horn the WRONG device into an application it wasn't intended and isn't suitable or appropriate for, and then blaming the thing that doesn't work rather than the person who mis-used the wrong part in the first place??

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Don't be insulting.
Wikipedia says "Many SSRs use optical coupling."