0
\$\begingroup\$

I have a system outdoors (~200W) that is powered from the house with a battery backup on UPS. When the UPS switches over to battery power, there is no way to currently generate a notification that the main power is lost.

The system has a LTE connection and a Raspberry Pi. I'm wondering if there's a relay that could sit between the AC power, and use the GPIO of the Pi to send a notification that the UPS has switched over?

What kind of relay should I be looking for? What things do I need to consider?

\$\endgroup\$
1
  • \$\begingroup\$ are you certain that the ups does not have a monitoring port? \$\endgroup\$
    – jsotola
    Apr 23, 2020 at 2:19

3 Answers 3

1
\$\begingroup\$

You need a relay with a 120VAC coil (if in US or Canada, 240VAC elsewhere) and low current SPDT contacts. The relay coil would be connected in parallel with the UPS AC input.

\$\endgroup\$
1
\$\begingroup\$

Sounds like you just have to detect the loss of AC power, and nothing to do with the UPS, so an AC-adapter plugged into the input power and driving a signal relay with gold contacts (or just driving a transistor) would work.

You could use an AC-coil relay, but then the wiring would be at mains voltage, and typically the contacts are not appropriate for signal levels.

\$\endgroup\$
0
\$\begingroup\$

An AC mains-operated relay, with low coil consumption (around 1.2VA) and a set of gold-plated SPDT contacts, would suffice.

Here's the schematic.

enter image description here

\$\endgroup\$
0

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.