Relay compatible with CT

Electromechanical Relays
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1

I am going to be installing a radon mitigation system, with the fan in the attic, which is largely inaccessible. The electrical feed for the fan will originate at the main electrical panel in the basement. We want to monitor the fan to ensure that it is operating via the home security/alarm system.

I am a retired electrician. I thought I could put a small current transformer in the circuit breaker panel that would feed a relay with a contact which would open on loss of power.

The fan is designed to run continuously, should the fan motor fail, it should go into a locked rotor state tripping the breaker.

I would not want to create a spurious alarm with loss of normal utility power, until our whole home emergency generator picked up the load – so a relay with a time delay?

Would you be able to recommend some components which I could accomplish this with?

All thoughts are sincerely appreciated,

2

Hello @tlpoole23

Welcome to the TechForum

From what you have described you may want to look into an Uninterruptible Power Supply (UPS) instead. An off-time relay would do what you are describing, but if there is a loss of power the relay would also loss power so it would not work, and the fan would create a spurious alarm

3

Products like the CR9321-NPN exist which can very conveniently provide a contact closure in response to current flow, though as mentioned the time delay part brings some complexity.

Assuming what you’re after is a “don’t alarm just because the power glitched” sort of functionality, it seems you’d be looking for a condition where the power’s on but the fan circuit 'aint drawing any. You may wish to check your alarm system’s manual for the availability of any sort of configuration options regarding delays or logical AND conditions, as they may be very useful here.