## Power consumption

## Power consumption

(OP)

Hi,

I have the following doubt: My client wants to record the power consumption in KW/Hr. I can take the power measurement from the relay in Kw, how I can use this value to get the Kw/Hr consumption?

Thanks

I have the following doubt: My client wants to record the power consumption in KW/Hr. I can take the power measurement from the relay in Kw, how I can use this value to get the Kw/Hr consumption?

Thanks

## RE: Power consumption

## RE: Power consumption

## RE: Power consumption

kW * (time period, in seconds) * (1 hr / 3600 sec) = kWh

If you know the average kW for many specific time periods, just add do the above calculation and sum all of the periods.

(Note that kWh and kW/Hr are VERY different quantities).

## RE: Power consumption

A graph of kW versus time gives instantaneous consumption, which is what he is asking for. kWh would be the integral of the kW graph. Such a graph would provide a visual indication of demand fluctuations (kW/hr), but I have never seen a need to put a numerical value on such a quantity.

Depending on the particular rate schedule, utilities can charge for

Demand (kW)

Energy (kWh)

Fuel (kWh)

and perhaps other things such as capital cost of supply, although this is usually reflected in the demand charge (a per kW charge based on peak kW usage during a moving period). Decreasing the demand (peak shaving) is one of the most effective ways to cut the electric bill.

Regards,

William

## RE: Power consumption

I am not sure if you should need the variation of power in time KW/Hr as you requested. If still this needs to be estimated determine the tangent of the curve in several points along the desired interval.

Suggestions:

1- Check if the data for KW are in RMS or instantaneous value.

2- Are you only interested in active power P (kW) or total power S (kVA)?

## RE: Power consumption

Vince Socci

www.ontargettechnology.com

## RE: Power consumption