Strange behavior of my home inverter

I have a 1500W/970W home inverter. If I switch off the main incoming breaker to the house, the inverter kicks in immediately and there are no issues.
However, when there is a power outage with the mains incoming supply, the inverter fails to switch on.
What could be the reason? Isn’t manually tripping the incoming breaker the same as the mains supply going off, at least from the perspective of the inverter? How do I explain this behavior to the visiting service technician?

I’m pinging my electrician husband to see if he has any suggestions. @Bob_Blaylock?

I’m not an electrician, but:

If your inverter automatically comes on in a power outage without shutting off the breaker – isn’t there a risk of its putting power into the lines outside the house, thereby risking the lives of power company employees trying to fix the problem, who can only turn off the power from their end of the lines?

Don’t they therefore have to be set up so as to either somehow trip that breaker themselves, or else to only go on if someone has manually shut it off?

  A lot more detail about this “inverter” is needed.

  An inverter is a device which converts DC (as from a battery) to AC, and steps it up or down to the desired voltage.

  Assuming that the device you’re talking about is truly an inverter, then you must have some source of DC power to go into it.  A bank of batteries, perhaps?

  And from your description of the problem, I take it that it is supposed to be set up to power your home in the event of a power outage from the utility?  1500 watts is not very much for such a purpose.  That would be enough to power a good microwave oven, but not much else at the same time.

  Anyway, what @thorny_locust said could be very relevant.  Backup power systems for a home or other building need to be cut from the utility while they are operating, to avoid backfeeding power back into the utility’s lines.  This is primarily for the safety of utility workers that may be working on those lines, trying to restore power; but also because a backup power system for one building is surely not going to be robust enough to power all the other buildings that might be feeding off that utility line.  The usual mechanism is called an Automatic Transfer Switch (ATS); where, when the utility fails, the ATS disconnects from the utility, and connects to the backup power system.

  Perhaps yours is set up so that what you think is the main breaker is also set to activate your backup power system, in a more manual mode; where manually turning off that breaker activates the backup power.  It would certainly make sense for your system to be set up in some way to make sure that it is now allowed to backfeed into the utility; and if it is able to know the state of the main breaker, that would o be a way to do it.  Next time you have a power outage, try manually turning off the main breaker, and see if your “inverter” comes on.

  And if it’s really only 1500 watts, then know that while you’re running on it, you can’t run very much.

I’m going to take a wild guess that this may be something like a Tripp-Lite PowerVerter. These are combination battery chargers and inverters. They normally range from about 750 watts to 2000 watts and are surprisingly common for emergency systems.

My (admitted) guess might be that the house is losing only one leg of the service coming into the house. Most of the lights go out, but there is still power to one side of the center-tapped transformer serving the residence. Maybe the “inverter” is on the leg that is still energized. But when the master breaker is turned off, both legs are disconnected.

Again…totally a SWAG.