Capacitor Bank and

Improvement of power

factor

Instructor

Rethwan FaizAssistant Professor

AIUB

Hello! Every One

American International University-Bangladesh (AIUB)Group Members-1.Shahriar Niloy. 14-26876-2 2.Kabir,Md.Ahshan 14-26903-23.Nurnobe ,Md. 14-26845-24.Hossain,Mohammad Ismail 14-27342-25.Shahabuddin,khan Istiak 13-24372-2

Contents:•Capacitor Bank•Power factor•Causes of low power factor•Disadvantages of low power factor•The Need for Power factor correction•Methods for improving Pf•Advantages of power factor correction•How capacitor Bank install in the plant•Reference

What is Capacitor Bank?A  capacitor bank  is a group of several capacitors of the same rating that are connected in series or parallel with each other to store electrical energy . The resulting bank is then used to counteract or correct a power factor lag or phase shift in an alternating current (AC) power supply.

What is the reason for using it? Capacitor banks are generally used in

substations. Since most of the household and industrial appliances are either resistive(eg. incandescent light,

heater, etc.) or inductive(e.g. refrigerator, air-conditioner, motor, etc).

The capacitive load of the capacitor bank will help to adjust the power factor as close to 1 as possible, in

which case the voltage and current are in phase and deliver maximum usable

power to the load.

Power Factor:  The power factor is the ratio of the real

power that is used to do work and the apparent power that is supplied to the circuit.

The power factor can get values in the range from 0 to 1.

When all the power is reactive power with no real power (usually inductive load) - the power factor is 0.

When all the power is real power with no reactive power (resistive load) - the power factor is 1.

The power factor can be expressed in two ways:■ Power factor (pf) = Useful power

(kW) divided by the total power (kVA),or

■ Power factor (pf) = The cosine of the angle between useful power and total power= cos ø.

Cause of low power factor:

Low power factor results when KW is small in relation to KVA.

What causes a large KVAR in a system? Inductive Loads• Transformer• Induction motors• Induction generators (Wind mill

generators)• High intensity discharge (HID)

lighting

Disadvantages of low power factor:

• The increase in reactive power increases the current flowing through the network

• Large copper losses• Large KVA rating and size of electrical

equipment• Greater conductor size and cost• Poor voltage regulation and large

voltage drop• Low efficiency• Reduced handling capacity of the

system

What can I do to improve power factor?You can improve power factor by adding power factorcorrection capacitors to your plant distribution system.

95% power factor provides maximum benefitTheoretically, capacitors could provide 100% of needed reactivepower. In practical usage, however, power factor correction toapproximately 95% provides maximum benefit.

Other methods of improving PF :

Synchronous Condenser

Phase Advancer

■ To reduce losses in the distribution system

■ Reduction of electricity bills■ Extra kVA available from the existing

supply■ Reduction of I2R losses in transformers

and distribution equipment■ Reduction of voltage drop in long

cables.■ Extended equipment life – Reduced

electrical burden on cables■ and electrical components.

How much can I save by installingpower capacitors?

Where should I install capacitors in my plant distribution system?

At Load-Because capacitors act as kVAR generators, the most efficient placeto install them is directly at the motor, where kVAR is consumed.Three options exist for installing capacitors at the motor.

Want big impact?Use big image.

At the service feeder-When correcting entire plant loads, capacitor banks can be installedat the service entrance, if load conditions and transformer sizepermit. If the amount of correction is too large, some capacitors canbe installed at individual motors or branch circuits.When capacitors are connected to the bus, feeder, motor controlcenter, or switchboard, a disconnect and overcurrent protectionmust be provided.

References-i. https://en.wikipedia.org/wiki/Traffic_lightii. http://circuitdigest.com/electronic-circuits/fo

ur-way-traffic-light-circuitiii. https://www.youtube.com/watch?

v=_XtsEVTrogc&feature=youtu.be iv. http://www.powershow.com/view/1f2279-

MTA5Y/Traffic_Signs_powerpoint_ppt_presentation

What about maintenance?Capacitors have no moving parts to wear out and require very little maintenance.Check fuses on a regular basis. If high voltages,harmonics,switching surges, or vibration exists, fuses should be checked more frequently.

References-i. International Journal of Emerging Technology

and Advanced Engineering Website: www.ijetae.com (ISSN 2250-2459, ISO 9001:2008 Certified Journal, Volume 4, Issue 8, August 2014)

ii. http://www.eaton.com/electrical.iii. http://www.electrical4u.com/capacitor-bank-

reactive-power-compensation/