223V+ on 208Y/120V 3P/4W Common?

[mightymx]

I am trying to verify the supply voltage to a commercial building in the US (I am having no luck getting in contact with the electrical company). I believe it is supposed to be 208V, however when I check the line-line voltages, all three are reading 223-224V. Is it common for 208V to be supplied this much higher? The panel is labeled 208Y/120V 3P/4W, 225 amps. All three line-neutral voltages are 129-131V. Can someone confirm the nominal supply voltage is 208V based on the information I have provided. Thank you!

 

[waross]

That is a 120Volt system running about 6% high.
Some utilities like to keep the voltage a little on the high side to increase billing.
When I was the system engineer for a small island utility, I lost that fight with the General Manager.
The voltage stayed high.

 

[RRaghunath]

Yes, the voltage is high depending on when the measurement is done. During peak hours, the same could be a lower than 208 Volts.
The distribution transformers in the field are not provided with any feature for on-load correction of output voltage.
The nominal voltage output of the transformer is about 5% higher than rated, assuming the transformer input voltage stays rated. This is done to take care of transformer voltage drop when it is loaded.
If the voltage is unacceptable for any reason or high even during peak hours, distribution company will be obliged to take corrective measures, I suppose!

 

[waross]

The nominal voltage output of the transformer is about 5% higher than rated,

It's called regulation.
The PU regulation of a transformer is the PU voltage drop under load.
Consider possible primary voltage drop depending on the time of day, and the voltage drop in your service conductors when the transformer is fully loaded and transformer regulation of between 3% and 5%.
Expect the voltage to be closer to nominal or even less during peak loading.
The difference between %Impedance Voltage and regulation?
The power factor.
% impedance is measured at short circuit conditions and very low power factor.
% Regulation is measured or calculated at a representative power factor and rated load rather than short circuit.
% Regulation is less than %Impedance voltage.

 

[TugboatEng]

One problem I have experienced is that single phase power in the USA is typically 220-240v and 3 phase supplies 208v. Single phase motors are tolerant of the low voltage but resistive heating elements lose a substantial amount of capacity at 208 (30+% if my memory is correct). If they're using 3 phase power to drive 1 phase heating loads such as residential grade dryers, heaters, ovens etc... that may explain the preference for the higher voltage.

 

[waross]

It's 25%, Tug, but millions of apartment dwellers never notice the difference.
Most appliances run on 120 Volts, so no problem.
The oven heating on/off cycle just runs more on time. It may actually give closer temperature control of the ovens.
Any larger three phase motors will be 200 Volt rated or 208-230/240 Volt rated.
That would be for elevators and building HVAC.