Solid State Relays.

[Wp100]

Hi,

Have got two Crydom SSR, one 4A and one 2A.

My load is 4.7A, is it possible to either parallel the two relays to handle that load or to add a triac of heavier current handling to just one of them. I have some BTA 16A triacs but not sure if or how they could connect ?

thanks

 

[canadaelk]

If the SSRs are zero-crossing types you could get away with it (for a while). I would use the triac. See the Motorola/ON Semi datasheet for the MOC3009 for application info. E

 

[JimB]

Have got two Crydom SSR, one 4A and one 2A.

My load is 4.7A, is it possible to either parallel the two relays to handle that load

I suggest that such a connection is a really bad idea, you have no way of determining the way the current will split between the two devices.
The lower rated device would probably be overloaded.

JimB

 

[Reloadron]

I agree with JimB in that I would just use a SSR rated for your load including overhead rather than try to parallel SSRs.

Ron

 

[Stewart]

Hi Wp100
I am afraid that paralleling these relays would not be an option.
What will happen is that one relay would switch on a fraction of a second before the other, carry the entire load until the SCR in the output burnt out. This could fail open circuit, in which case the second relay will switch on and the same will happen to it, or it will fail short circuit.
Regards
Stewart