SUA1500l delayed relay click after turn off

[jeepster_apc]

I have a used Smart-UPS 1500. I remove the load, and press the off button. When the lights go out, I unplug the power at the wall socket.

After a few minutes, I hear a relay click. Not really a problem, I just find this strange.  It seems some slowly discharging capacitor is keeping a relay closed.

Is this usual behaviour?

[BillP · Accepted solution]

Yes, it is. This is the UPS braindeading itself and discharging the capacitors. It typically also causes the LEDs to flash on the front panel of the UPS, depending on model. All of this generally occurs 8-10 minutes after AC power is removed.