Lightobject.com Support Forum

I have a problem I am trying to solve. I will need to use (2) PT100 sensors with some kind of a control system. One sensor, "A" will be in a water tank. Sensor "B" will be attached to a heat source that is not always present. The idea is that when "A" is below its set-point, and, "B" is above its set point, a 9a 220V circuit will be completed, turning on a pump. If either either A or B conditions are not met then the pump will stay off. Only when conditions are met at both sensors should my pump power circuit be completed.(conditions met, means when A is below set point AND when B is above set point)

I was thinking it might be possible to use 2 of the JLD612's, wired in series. That way the circuit would be complete when both of them have their conditions met and the circuit would be inactive if either sensor does not have its conditions met.

Could someone please comment on this application and if it is feasible, also caution me on anything to be careful of and tell me how I would need to configure them. Will I need to use an external relay due to the high amps? Etc.

Thanks in advance for any help.

This will work if you use the mechanical relays bult into the JLD612s, fed by an external power source -- this will NOT work if you try to wire the SSR outputs of the 612s in series.

Then it will be a matter of setting the control parameters so that A is set for heating, and B is set for cooling and setting the SV values. Just wire up the C and NO terminals of the two relays of the two 612s in series with the big relay/contactor that controls the 9A 220V pump. Be careful about current through the built-in relays -- limit current through them to 1A MAX (even though they have a nominal 3A rating), so be careful about the coil current rating on the main relay/contactor.