What is Power Factor of Electrical System ?

Power factor is one of the most important theory in electrical industry. The phenomion of power factor is only affected in alternating current (AC) circuits.

The cosine angle between the current and voltage in an alternating current device is known as power factor and we can simply draw the power triangle and the cosine angle beweeen apperent and real power is known as the power factor.

Power Triangle

• Real Power (P)
• Reactive Power (Q)
• Apparent Power (S)

The effect of power factor is consider as disadvantage for the elelctrical system and folloing are several disadvantages of the system.

Disadvantages of lower power factors

1. Large KVA ratings are applied when low power factor occurs
2. When the power factor increases the size of the conductor also getting higher
3. Copper losses also become greater
4. Low voltage regulations occurs
5. Handling capacity of the power system get low due to low power factor effect

Why we getting low power factor in the system?

1. Alternating Current motors (induction motors) which having low lagging power factor
2. Most of the lighting loads are inductive sometimes (Except LED lights)
3. Loads on the power system very

How to improve power factor of the system?

1. By Using Static Capacitor: Static capacitors are which connect the capacitors which parral to the equipment which operates under low and lagging power factors.

Advantages of Static Capacitors

1. Reduce the losses of the system
2. The maintains of static capacitor are really easy
3. Static capacitors can easily installed
4. No rotating parts are involved in static capacitors
5. It can work under normal operating conditions (No special conditions required)

Disadvantages of Static Capacitors

1. Static capacitors are got very low lifespan ( 8-10 years)
2. Repair of such capacitors are uneconomical
3. These capacitors got really high tendency to get damage.

2. Synchronous Condenser:

Synchronous motors which take the leading where over excitation occurs known as a synchronous condenser.

Normally these synchronous condensers are connected parallel with the power supply

Synchronous condensers are taken the leading current out of the neutralize the lagging component of the power system.

Advantages of Synchronous Condensers:

1. The winding of the synchronous motors got higher thermal stability
2. Current which drawn by the motor can get change by any quantity
3. The fault of the system can easily remove by the synchronous condenser in the system

Disadvantages of the Synchronous Condenser:

1. Compare to Static capacitors synchronous condensers are high cost
2. So self-starting torque in the synchronous motor so auxiliary additional supply needs to provide for starting.
3. The high cost of maintenance required for synchronous condenser compares with static capacitors.
4. Normally this System create an additional noise into the system
5. Losses of the motors need to be accurate

3. Phase Advancers

Phase advancers are used to improve the power factor of the induction motor and normally phase advancer is a simple type of AC exciter.

Advantages of Phase Advancers

1. The phase advances are convenient to use where the synchronous motor unable to use
2. The exciting appears of the turns of the power supply and the lagging KVAR is getting reduced considerably.

Disadvantages of Phase Advancers

1. Phase advancers are not much economical for the motors which bellow 200 horsepower ratings.
2. Phase advancer is mounted on the shaft as the main motor

Why this power Factor Improvement is Important

Power factor improvement is really important for the consumer to pay the electric charge on the maximum demanded in KVA value.

The improvement of the power factor reduces the maximum KVA value of consumers power systems so savings can gain by the demand.

The number of electricity units directly depends on the power factor. When the power factor of such system is getting high, the power also getting high.

So the improvement of the power factor in plant improved the earning capacity.

Normally when we consider about the power stations the need to deliver more KW to meet to increase the power demand in the system.