Single Phase Power Equations
Power equations for single phased electrical systems.
Single phase power equations:
Real Power
Wapplied = U I PF / 1000 (1)
where
Wapplied = real power (kilowatts, kW)
U = voltage (volts, V)
I = current (amps, A)
PF = power factor - 0.7 - 1
Total Power
W = U I / 1000 (2)
Brake Horsepower
- Brake horsepower is the actual power delivered to or by a shaft.
WBHP = U I PF μ / 746 (3)
where
WBHP = brake horsepower (hp)
μ = device efficiency
Example - Horsepower vs. Current and Voltage
An AC motor consumes 8 amps of current. The voltage supplied is 12 V, the efficiency of the system is 96% (0.96) and the power factor is 1. The horsepower can then be calculated as
WBHP = (12 V) (8 A) (1) (0.97) / 746
= 0.125 HP
≈ 1/8 HP