Elevators

[steve66]

Here is one from an elevator submittal package:

Confirmation that the emergency standby power generator and/or building can accept the power generated to and from
the elevator during both Hi-Speed and Deceleration as shown on the layout drawing package. In cases where the generator
and/or building load is not electrically sized to handle the power return from the regen drive, additional separate chopper
and resistor units are available for purchase but not included in this proposal.

I'm wondering how one would do this. Specifically, how does anyone know what loads would be running while the elevator is regenerating power?

Or does the utility transformer absorb any overvoltage and transfer it back to the grid?

 

[GoldDigger]

Here is one from an elevator submittal package:

Confirmation that the emergency standby power generator and/or building can accept the power generated to and from
the elevator during both Hi-Speed and Deceleration as shown on the layout drawing package. In cases where the generator
and/or building load is not electrically sized to handle the power return from the regen drive, additional separate chopper
and resistor units are available for purchase but not included in this proposal.

I'm wondering how one would do this. Specifically, how does anyone know what loads would be running while the elevator is regenerating power?

Or does the utility transformer absorb any overvoltage and transfer it back to the grid?

When the grid is up. any excess regen power beyond local loads is transferred back into the grid. Just like Solar PV but on a small infrequent scale. If they do not have a bidirectional meter, this will increase their bill.
But the OP is specifically talking about when on backup generator power. There will be no grid connection and the generator cannot absorb excess power. There will be loss of voltage regulation, shutdown or even generator damage. Hence the possible need to add a resistor bank.

Probably the only load you can count on during a power outage event will be the exit lighting. Everything else might be powered off while elevators are still in use to exit the building. But an average power level, minus the power to elevator(s) themselves would be a good place to start.

 

[steve66]

Of course, so one or the other of the transformer and generator would normally be connected to the elevator.

So we just have to make sure they are large enough to absorb the reactive power.

 

[don_resqcapt19]

Of course, so one or the other of the transformer and generator would normally be connected to the elevator.

So we just have to make sure they are large enough to absorb the reactive power.

This is not reactive power...this is regenerated power when the elevator converts physical movement to electrical power as part of the breaking operation. You would need to consult with the generator manufacture on the ability of the generator to function correctly with a regenerative load.