Demand Calculations

Key

kW = Kilowatt (Demand)

kWh = Koliwatt Hours (Energy)

I = Current

I1 = Phase 1 Current
I2 = Phase 2 Current
I3 = Phase 3 Current

V = Voltage

W = Wattage

pn = Phase to Neutral

pp = Phase to Phase

Basic kW Calculation

The most basic calculation for demand

kWh ÷ Hours = kW

Calculating Demand from Pulses

If you are trying to calculate Instantaneous Demand and have a pulse meter, try this equation

kWh / Pulse x 3,6000 sec/hour —————————————— = kW # of seconds between pulses

Single-Phase Calculation

Most Single-Phase applications will be for Residential and Small Commercial buildings

I x V = W

W ÷ 1,000 = kW

Balanced 3-Phase Power Measurement

Use if all 3 Phases pull the same amount of current

I x Vpp x 1.73 = W

W ÷ 1,000 = kW

Individual 3-Phase Current Measurement Phase to Neutral

Use if the Phases pull different amounts of current. Most simple calculation for these conditions

(I1 + I2 + I3) x Vpn = W

W ÷ 1,000 = kW

Individual 3-Phase Current Measurement Phase to Phase

Another method of calculating Demand if the Phases pull different amounts of current

(I1 + I2 + I3) x Vpp x .577 = W

W ÷ 1,000 = kW

Want to know more about Demand? Contact the experts at Brayden Automation Corp.