Frequently Asked Questions

Detecting AC Power Failure

The RFC-1/B has a power failure alarm that causes the system to call an operator after a failure. This alarm works fine when notification is only needed after AC power returns. In the absence of a generator there is nothing to control and if there is a generator then power failure is less of an issue.

There are plenty of reasons to have the RFC-1/B monitor for AC power failure: generator failure, brown-outs, etc. The built-in power failure alarm may not be sufficient in these conditions.

An uninterrupted power supply will allow the RFC-1/B to operate normally when AC power fails. An inexpensive home-office UPS will typically power the RFC-1/B for an hour or more.

Monitoring AC power with the RFC-1/B is easy. Required items are a small wall-plug power transformer in the 3-9 VDC range and an unused telemetry channel. The output current is not critical as almost no current will be drawn.

Program the telemetry channel with the unit word "volts" and select an appropriate scale, probably "204.0", with linear tracking. Use the link on the right if you need help with programming.

Use a meter to read the AC line voltage at the wall outlet and adjust the trim pot on the telemetry channel until the channel gives the same reading as the meter. The RFC-1/B can now report the line voltage at the site.

The RFC-1/B can be programmed to monitor the AC line voltage input and generate an alarm just like any other telemetry input.