I have two issues happening at the same time (very much related).

  1. The APC brand UPS backups in my office all start buzzing at the same time, then click once every 5-10 minutes. This happens at all times of the day.
  2. If my car is plugged in (Tesla wall charger), the Tesla app starts over when I hear the noise the APCs make. It does this 3 or 4 times, then the car turns the charging off and I get an alert that the charging is interrupted.

Note, I have tried two different chargers and both do the same thing. (One charger is the wall charger, and the other is the charger that is never used that came with the car.)

I have called the electrician and the power company and both parties say that everything is normal. I am having the breaker boxes exchanged out ($5000 later.) This is scheduled, but doubt this is the cause also.

I don't think this was a surge as the second car charger that I use still does the same thing, and it was not plugged in when this problem first started.

What could the issue here be?

  • \$\begingroup\$ This might be a local thing: what's an APC? \$\endgroup\$ – mmmm Feb 7 at 0:28
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    \$\begingroup\$ the AC power is dropping out ... what else would make a UPS kick in? \$\endgroup\$ – jsotola Feb 7 at 0:35
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    \$\begingroup\$ Brownouts. The make power line recorders, but they are rather expensive. Maybe you could rent one. With solid evidence, maybe the power company will act. fluke.com/en-us/product/electrical-testing/power-quality/vr1710 \$\endgroup\$ – Mattman944 Feb 7 at 0:37
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    \$\begingroup\$ the UPS may have a logging feature ... see if you can query the UPS about any anomalies ...... btw, the device is a UPS, not an APC .... APC is a brand name \$\endgroup\$ – jsotola Feb 7 at 0:38
  • \$\begingroup\$ @mmmm APC is a popular brand of UPSes. \$\endgroup\$ – Hearth Feb 7 at 1:03

This could be due to many reasons and by inspecting the cause of each possibility you may troubleshoot the problem depending on your context:

  1. Brownouts:

    • high electricity demand even temporarily like a start-up of heavy equipments.
    • related in some cases to the weather condition. Try to correlate the timing.
    • construction project or civil works in the neighborhood.
    • malfunction of a smart meter (if applicable).
  2. Frequency or voltage fluctuation:

    • a ups can switch to bypass mode on voltage or frequency fluctuations.
    • some ups have a switch to select between narrow or wide frequency tolerance.
  3. Harmonics:

    • a ups at the same time creates harmonics (charger) and is vulnerable to harmonics making it switching to bypass.
    • harmonics can be created by any nonlinear equipment. Do not underestimate small machines in inspecting this cause like lighting dimmers (especially dimmers), battery chargers, ...
    • elevators are double suspects: heavy start-up and harmonics creators.
  4. Electrical installation problem:

    • Sometime loose connections may be a source of trouble creating resistance in the circuit and they are dangerous on the safety level since they may cause fire.
    • wires dimensioning and simultaneity issues

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