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# Single Phase Power Equations

## Power equations for single phased electrical systems.

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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

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## Citation

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• The Engineering ToolBox (2005). Single Phase Power Equations. [online] Available at: https://www.engineeringtoolbox.com/single-phase-electrical-d_887.html [Accessed Day Month Year].

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12.8.9

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