Question

A small factory has different types of loads which are grouped together as follows

A) induction motors : 1200 hp, 0.8 lag PF

B) Heating loads: 100kW at unity PF

A 3 phase synchronous motor is installed at the factory to improve the factory's overall power factor. Calculate how much reactively power per phase the synchronous motor must supply to the system to maintain an overall power factor of 0.9 lagging. 1 hp = 0.746 kW

together as follows: a. Induction motors: 1200 hp, 0.8 lagging power factor; b. Heating loads: 100 kW at unity power factor. A three-phase, synchronous motor is installed at the factory to improve the factory's overall power factor. Calculate how much reactive power per phase the synchronous motor must supply to the system to maintain an overall factory power factor of 0.9 lagging [1 hp=0.746 kW).

Answer 1

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е, а Top Heating Lea lea I m m For induction motor, Active power absorbed, P₂ = 1200 СР 1200 » 0.74 6 895.2 KW. Pf cos Oz - 0.8 dag) O, cast (0.8) 36.860 Reactive power taken, 2 P tan 02 895.2 tan 36.860 671. 4 KVAR For heating load, Қа Active power taken, P, 2 100 Pf - cose = 1 => 0,20

Reactive power taken, For the synchronous motor, sogno Let the reactive power supplied by the motor be Qc and it is calso assumed does not absorb any active power. that it Total active power taken by the system, p. P + P₂ 100 + 895.2 Z 995. 2 KW Total reactive power taken by the system Q = Q & Q - Qc z O + 671.4 - Q 2 (671.4 - Q.) KVAR 1 Given over all power factor 0.9 Ilag) 27 cos e = 0.9 2 0 = 25.840