The power factor correction means bringing the
power factor of an AC circuit closer to one by using the equipment which
absorbs or supply the reactive power to the AC circuit. Generally, the power
factor correction can be done by using the capacitor and the synchronous motor
in the circuit. The power factor correction will not change the amount of real
power, but it will reduce the apparent power and the total current drawn from
the load.
Video source By- Learning Engineering
The power factor correction methods are mainly classified into three types:-
In three phase system, Power factor Correction
means reducing the phase difference between voltage and current. Since majority
of loads are of inductive nature, they require some amount of reactive power
for them to function. This reactive power is provided by the capacitor or bank
of capacitors installed parallel to the load. They perform as a source of local
reactive power and thus less reactive power flows through the line. Mainly they
reduce the phase difference between the voltage and current.
The three phase synchronous Condenser was running
without the mechanical load, and it is connected in parallel with the load. It
absorbs and generates the reactive power by varying the excitation of the motor
field winding. For inductive loads, synchronous condenser is connected towards
load side and is overexcited. This makes it perform like a capacitor. It draws
the lagging current from the supply or supplies the reactive power.
The synchronous condenser has some disadvantage
like it is costly and their installation; maintenance and operation are also
not easy.
This is an AC exciter generally used to improve
power factor of induction motor. They are mounted on shaft of the motor and is
linked in the rotor circuit of the motor. It improves the power factor by
providing the exciting ampere turns to produce required flux at slip frequency.
Further if ampere turns are increased, it can be made to operate at leading
power factor.