Generator Voltage output Adjustment

[faresos]

Hello All:

Can we adjust the generator voltage output to compensate for voltage drop, if so what is the percentage? The generator is 800KW, 480Y/277V and about 400ft from the building. Other wised I might need to increase the conductors size.

Thanks,

 

[ron]

Is the load always the same?

At low load, the voltage would be very high and at varied load levels it would sway from high to some normal value.

 

[junkhound]

Hello All:

Can we adjust the generator voltage output to compensate for voltage drop, if so what is the percentage? The generator is 800KW, 480Y/277V and about 400ft from the building. Other wised I might need to increase the conductors size.

Thanks,

You can always move the sense points of the field control down to the load, then voltage drop will be accommodated for by the regulator.

 

[faresos]

Is the load always the same?

At low load, the voltage would be very high and at varied load levels it would sway from high to some normal value.

I'm sure the load will varies from time to time. This is like an office building with many IT server racks (fed from 300KVA UPS). The building is served from 1000KVA transformer, which I anticipate the actual load will not exceed 600KVA. So for high load, would the voltage regulator adjust the voltage automatically? Are there voltage sensors at the main service bus (or ATS) to monitor the voltage and the voltage regulator adjust the voltage accordingly?

 

[faresos]

You can always move the sense points of the field control down to the load, then voltage drop will be accommodated for by the regulator.

Are the sense points part of the ATS? Is the voltage regulator function is to maintain the desire voltage value at the load and is done automatically?

 

[ron]

Are the sense points part of the ATS? Is the voltage regulator function is to maintain the desire voltage value at the load and is done automatically?

Voltage regulator sensing happens at the generator.

Data Center loads may be too sensitive for high voltage during load overall loads. The UPS may go to battery on what it considers a "bad" voltage source.

Properly sizing the feeder conductor is the way to go

 

[Bugman1400]

Raising the gen bus voltage to compensate for VD is the essence of Load Drop Compensation (LDC) and is done frequently. You need to ensure that your local gen bus is never above 1.05pu or any rated nameplates. You also need to do the calc to make sure this will work. If the VD is too severe, just raising the gen bus voltage may not be enough.

 

[GoldDigger]

You can always move the sense points of the field control down to the load, then voltage drop will be accommodated for by the regulator.

It is fairly common for battery chargers and IT equipment electronic power supplies to have terminals for remote voltage sensing as part of their standard configuration. If you do not need to use the remote sensing you just jumper the sensing terminals to the output terminals.

Is there equivalent built-in provision for remote sensing in standby generators, or would it require field modifications?

 

[junkhound]

It is fairly common for battery chargers and IT equipment electronic power supplies to have terminals for remote voltage sensing as part of their standard configuration. If you do not need to use the remote sensing you just jumper the sensing terminals to the output terminals.

Is there equivalent built-in provision for remote sensing in standby generators, or would it require field modifications?

Have seen Basler and Cat regulators where one simply moves the sense voltage connections out to the load and brings those leads back to the regulator thru 10 ohm resistors,
(page 8 on link, first schematic I pulled up on internet)

Am not sure how NEC covers where the OCP goes if sense moved, different regulators likely have different OV schemes also.


http://doc.diytrade.com/docdvr/1198946/14153731/1282325988.pdf