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exp 19

# exp 19 - Experiment 1 9 L p a t t Var Volt-Ampere and Power...

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Experiment 1 9 Lpatt, Var , Volt-Ampere, and Power' Factor OBJECTlVE To study the relationship among wait, var and vdt-ampere. To determine the apparent, active and reactive power of an inductive load. To improve the power factor of an inductive load. We now know the fdlowing facts: a) Apparent power supplied to a load b the simple product of voltage and current. b) Active power supplied to a load is measured by a wattmeter. When reactive poser is imrohred, the apparent power is larger than the active power. Reactive power may be inductive or capaWe. in most electromechanical devices the reactiie power will be inductive due to the inductance presented by coils. Reactive power can be calculated by the equaW Reactive power = d(Apparent power? - (Real power2) ( 1 1 If the phase angle between the vottage and current is known, the active power can be found by the equation: Active power = E x 1 x cos @ = Apparent Power x cos 4 (2) The ratio of active power to apparent power is called the pawer factor of an AC circuit. Power factor can be found by the equation: PF = PIE1 = Active Power / Apparent Power (3) The value of the pawer factor depends on how much the current and voltage are out of phase. When the current and voltage are in phase, the active is equal to I x E, or in other words, the power fador is unity. When current and voltage are out of phase by 90°, as in a purely - ~ e or induct'i ciradt, the power factor is zero, resulting in a zero value of achral power. In circuits containing both resistance and

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I Watt, Var, Volt-Ampere, and Power Factor reactance, the value of the power factor is some value between one and zero. If the phase angle c\$ between the voltage and current is known the
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