SSR Issue

brynod

Member
Join Date
Feb 2012
Location
CT
Posts
5
I am using a Magnecraft 861 series Zero cross 10amp SSR to control a small inductive load (1.5 amps) of a fluorescent light fixture. I am providing the coil voltage from an AB remote IO 16 point output module. When the output is energized and I provide 116v ac to the SSR coil the relay will not change state. When I put a VOM's test leads across the coil the relay will change state and functions properly. Any suggestions?
 
I have verified the voltage first at the contact of the output module and also at the coil of the relay. It appears that the resistance of either a digital or analog meter allows the relay to change state.
 
More likely the SSR won't switch OFF without the additional load of the VOM.

Model number of the AB output card please?

If it's a standard triac output, you will need a load resistor to be able to drive the SSR.
 
Which part number are you using?
http://www.bb-elec.com/bb-elec/literature/861Series.pdf

Off state triac leakage is almost definitely going to hold those SSRs in the conducting state.

You can add a load to the SSR coil (incandescant pilots lights can work nicely, often adding a useful feature to the machine), or trade your SLC triac module for a relay module.

If your using the very common 1746-OA16, you can swap it for a 1746-OW16 with no wiring changes, but be sure to study the effect that may have on other connected equipment. The relay module may introduce a tiny switching delay, and is typically good for about 500,000 cycles at full rated load before you would start to see contacts sticking.
 
Last edited:
Unfortunately not. The hardware is already mounted in the feild. I am considering a bleeder resistor across the load output of the relay. I am leaning towards the relay never truly turning off and by applying the meter is enough resistance to change the relay state.
 
Yes, I would be 90% sure you are right. You can be 100% sure by looking up the off state leakage of the 1794-OA16, or by adding a load. Any 120vac load in parallel with the SSR coil that doesn't push the total beyond the limit of the output point can work. It could be a tiny little neon light or a resistor or a mechanical relay, as long as it draws enough to pull the AC voltage down below 10vac when the triac is off.
 

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