Switch Controlling Solenoid
Switch Controlling Solenoid
(OP)
I have a very basic question. A system with two 120VAC pressure switches needs to activate a 3-way air solenoid that would open the valve if either switch activates. Can I just splice these wires together and attach them to the solenoid?





RE: Switch Controlling Solenoid
If the solenoid has a 120 Vac coil, it would be correct to series the pressure switch contacts that open to de-energize the solenoid.
Consider the pressure shelf positions. If one switch is a low pressure switch, wire the common and normally open switch. For the low trip the contact is open while sitting on the shelf thus below the trip condition. The normally open contacts close after sufficient pressure exists. If the other switch is a high pressure switch, you would wire the common and normally closed contact. On the shelf the high pressure switch would not exceed the setpoint thus would be closed. For a high pressure trip the contacts open after the pressure increases above setpoint. Also, if the trips must be clear to start something, you could need a startup time delay with a contact across the low pressure switch contact that permits increasing to satisfactory pressure before applying the low pressure contact.
We also like additional contacts that generate alarms that indicate why the solenoid tripped. Most of us prefer transmitters that can indicate the pressure thus provide indication of the measurement device failure. Pressure switch failure can be undetected for a very long time without anyone being aware.
RE: Switch Controlling Solenoid
RE: Switch Controlling Solenoid