Swapping out Electromechanical Relay for SSR

Thread Starter

iceburnhex

Joined Jun 14, 2022
5
Good afternoon all,

I was working on a project for basically opening/shutting a curtain via Alexa, and using a Relay Module I found online to run the software between it. My question is, would a Solid State Relay (SSR) work for a replacement of the louder and larger Electromagnetic Relays on the device?

The relays use 5VDC to run, and I checked and the current through the relays to be 0.7mA running, which I believe is just the signal to tell the curtain control box to run the motors a certain direction. I've never used any SSRs before, and while I found some datasheets on them, I'm not really sure what I should be comparing on them for the current relays I have.

Any direction or help would be great. I have no problem with orders from places like DigiKey and such either, so if you have any recommendations of a certain SSR, feel free to link it as well. Much appreciated!

Current Relays: W14-1CST
 

nsaspook

Joined Aug 27, 2009
10,405
What type of signals (AC/DC direct motor power, AC/DC motor power trigger, etc ...) are the relay contracts switching. Dry relay contacts are pretty universal in what they can switch but selecting a proper SSR requires circuit details that might make it not worth the effort if it's working with relays.
 

Thread Starter

iceburnhex

Joined Jun 14, 2022
5
What type of signals (AC/DC direct motor power, AC/DC motor power trigger, etc ...) are the relay contracts switching. Dry relay contacts are pretty universal in what they can switch but selecting a proper SSR requires circuit details that might make it not worth the effort if it's working with relays.
So the Control Box on the Curtain itself is powered separately, and uses an input from an external source to switch the motors in one direction or another. From what I can tell, the Relay 1 will switch ON, and draw a continuous 0.6-0.7mA until the curtain is in the close position. Then it switches back off. To Open it, Relay 2 switches ON, and does the same thing, until the curtain is Open.

I suppose my question becomes is it possible to replace these types of Relays with SSR, or is it something that would usually require a rebuild of the control circuitry to do the same thing with SSRs instead.
 

nsaspook

Joined Aug 27, 2009
10,405
So the Control Box on the Curtain itself is powered separately, and uses an input from an external source to switch the motors in one direction or another. From what I can tell, the Relay 1 will switch ON, and draw a continuous 0.6-0.7mA until the curtain is in the close position. Then it switches back off. To Open it, Relay 2 switches ON, and does the same thing, until the curtain is Open.

I suppose my question becomes is it possible to replace these types of Relays with SSR, or is it something that would usually require a rebuild of the control circuitry to do the same thing with SSRs instead.
Sure it's possible but not necessarily a trivial part replacement. What's the open circuit voltage on the Curtain Control Box contacts the relay switches?

A small MOSFET optocoupler SSR is likely what you need as a relay replacement.
https://www.infineon.com/cms/en/product/power/solid-state-relay/photovoltaic-relays/pvg612a/
 

Reloadron

Joined Jan 15, 2015
6,953
Good afternoon all,

I was working on a project for basically opening/shutting a curtain via Alexa, and using a Relay Module I found online to run the software between it. My question is, would a Solid State Relay (SSR) work for a replacement of the louder and larger Electromagnetic Relays on the device?

The relays use 5VDC to run, and I checked and the current through the relays to be 0.7mA running, which I believe is just the signal to tell the curtain control box to run the motors a certain direction. I've never used any SSRs before, and while I found some datasheets on them, I'm not really sure what I should be comparing on them for the current relays I have.

Any direction or help would be great. I have no problem with orders from places like DigiKey and such either, so if you have any recommendations of a certain SSR, feel free to link it as well. Much appreciated!

Current Relays: W14-1CST
OK, in addition to your subsequent post let's try and clean this up a little. You have a curtain which has a curtain open and close module. May we assume that the curtain control module has maybe a common or ground terminal along with an open terminal and a close terminal? That the open/close module has 5.0 volt inputs? Maybe the curtain control module just has a ground or common and a single terminal so when you apply a signal the curtain opens till it stops on its own and closes in the same manner? The currents you mention of 0.7 mA make no sense as I have never seen a relay coil which takes 0.7 mA (700 uA).

So exactly which mechanical relay(s) are you looking to replace? Most imported relay cards compatible with Alexa use a small standard Songle form C relay normally a Songle SRD-05VDC-C part number or similar. Then don't make any noise to speak of so my guess is you are not talking about those relay(s). This only leaves the likely mechanical relays in the curtain control module and I doubt those relays have 0.7 ma coil current. The module may only draw 0.7 mA at the open close terminal(s) but I doubt that is the curtain motor current? The actual curtain likely uses limit switches to tell the controller module when the curtain is fully open or fully closed. Less knowing exactly how things work and are configured it's hard to give a direct answer as to replacing mechanical relay(s) with a SSR.

Ron
 
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