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Written by Stelios Kontozoglou
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Tuesday, 27 October 2009 08:32 |
OHM'S LAW
Resistance, R = Voltage [ohm]
Current
Current, I = Voltage [ampere]
Resistance
Voltage, V = Current x Resistance [volt]
SINGLE PHASE A.C. POWER
Power = V x I x cosΦ [watt]
where cosΦ = power factor
THREE PHASE A.C. POWER
Power = 1.732 x V x I x cosΦ [watt]
SERIES A.C. CIRCUIT
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Reactive or 'Idle' Component = tanΦ x kW [kVAR]
Reactive kVA = kVAR = (kW2 + kVAR2)½ [kVA]
sinΦ
Active Component = kVA x cosΦ [kW]
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EFFICIENCY
Efficiency = 746 x Output Horsepower
Input Watts
INDUCTION MOTOR
Synchronous Speed, Ns = 120 x frequency (hertz) [rpm]
number of poles
Actual Speed, N = Ns(1-slip) [rpm]
Rotor output = Torque x 2 x π x N [watt]
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