**What is Control Gear?**

An electrical ballast (sometimes called control gear) is a device intended to limit the amount of current in an electric circuit.

Ballasts vary greatly in complexity. They can be as simple as a series resistor as commonly used with small neon lamps or light-emitting diodes (LEDs).

For higher-power installations, too much energy would be wasted in resistive ballast, so alternatives are used that depend upon the reactance of inductors, capacitors, or both. Finally, ballasts can be as complex as the computerized, remote-controlled electronic ballasts now often used with fluorescent lamps.

**Why Should I Improve My Power Factor?**

1) Lower utility fees

2) Eliminating the power factor penalty

3) Increased system capacity and reduced system losses in your electrical System

**What is Importance of power factor in distribution systems?**

The significance of power factor lies in the fact that utility companies supply customers with volt-amperes, but bill them for watts. Power factors below 1.0 require a utility to generate more than the minimum volt-amperes necessary to supply the real power (watts). This increases generation and transmission costs. For example, if the load power factor were as low as 0.7, the apparent power would be 1.4 times the real power used by the load. Line current in the circuit would also be 1.4 times the current required at 1.0 power factor, so the losses in the circuit would be doubled (since they are proportional to the square of the current). Alternatively all components of the system such as generators, conductors, transformers, and switchgear would be increased in size (and cost) to carry the extra current.

Utilities typically charge additional costs to customers who have a power factor below some limit, which is typically 0.9 to 0.95. Engineers are often interested in the power factor of a load as one of the factors that affect the efficiency of power transmission.

**How many key components are there in Ballast circuit?**

There are 3 key components in the circuit :

Ballast (or Choke) - the device that controls the current through the lamp

Starter - the switch that starts the lamp

Capacitor - the component that corrects the power factor

**What Causes Low Power Factor?**

What causes Low PF answer is Large KVAR

What causes a large KVAR in a system? The answer is inductive loads.

What are the Inductive Loads:

Answer is :

Transformers

Induction motors

Induction generators (wind mill generators)

High intensity discharge (HID) lighting

**What is the Power Factor ?**

To understand power factor, we ll first start with the definition of some basic terms:

KW is Working Power (also called Actual Power or Active Power or Real Power).

It is the power that actually powers the equipment and performs useful work.

KVAR is Reactive Power.

It is the power that magnetic equipment (transformer, motor and relay)

needs to produce the magnetizing flux.

KVA is Apparent Power.

It is the vectorial summation of KVAR and KW.

Power Factor (P.F.) is the ratio of Working Power to Apparent Power.

PF = KW/(KW+KVAR) = KW/KVA

**What is Power Factor Correction?**

It is often desirable to adjust the power factor of a system to near 1.0. This power factor correction (PFC) is achieved by switching in or out banks of inductors or capacitors. For example the inductive effect of motor loads may be offset by locally connected capacitors. When reactive elements supply or absorb reactive power near the load, the apparent power is reduced.

**How do we measure Power Factor ?**

Measuring power factorPower factor in a single-phase circuit (or balanced three-phase circuit) can be measured with the wattmeter-ammeter-voltmeter method, where the power in watts is divided by the product of measured voltage and current. The power factor of a balanced polyphase circuit is the same as that of any phase.

**What is the THD ?**

THD is defined as the RMS value of the waveform remaining when the fundamental

is removed. A perfect sine wave is 100%, the fundamental is the system frequency of 50 or 60Hz. Harmonic distortion is caused by the introduction of waveforms at

frequencies in multiplies of the fundamental ie: 3rd harmonic is 3x the fundamental

frequency / 150Hz. Total harmonic distortion is a measurement of the sum value of

the waveform that is distorted.

**What are the Problems High THD can cause ?**

Harmonic currents add to the fundamental load current and can affect revenue billing

by introducing errors into kilowatt hour metering systems, which will directly increase the net billable kilowatt demand and kilowatt hour consumption charges.

The commercial effects of harmonic distortion to power quality are dramatically

shorter equipment lifetimes, reduced energy efficiency and a susceptibility to

nuisance tripping. The costs of supply interruption are high, however caused,

resulting in data corruption, disruption of process manufacturing and failure of

telecommunications facilities etc.

**What is Crest Factor ?**

The Crest Factor is equal to the peak amplitude of a waveform divided by the RMS value. The purpose of the crest factor calculation is to give an analyst a quick idea of how much impacting is occurring in a waveform. Impacting is often associated with roller bearing wear, cavitation and gear tooth wear.

In a perfect sine wave, with an amplitude of 1, the RMS value is equal to .707, and the crest factor is then equal to 1.41. A perfect sine wave contains no impacting and therefore crest factors with a value higher than 1.41 imply that there is some degree of impacting.

**What are important Characteristics of Ballst ?**

Following Characteristics differentiate Efficiency of ballst from other each other ?

1.Power Factor

2.THD

3.Ballast Factor

4.Crest Factor at Input and Output

5.Lumens / Watt

6.Ballast Input Current

7.Ballast Out Put Current

8.Ballast Out Put Voltage

9.Ballast Input Power

10.Ballast Out Put Power

11. Ballast Out Put Frequency

**What is Ballast Factor?**

The Ratio of Ballast output power to Ballst input Power is the Ballast Factor .

**What is importance of Ballast Out Put Current ?**

All Tubes are rated to work most efficiently at certain Ballst Out Put Current or Tube Input Current. Current less than Rated current or more than Rated current ( Within the specified Tolerance range) will affect the life of Tube. Different tubes like T5, T4 , PLC or PLL have different rated currents .It is very important that ballast is well matched with the Tube Current Rating . We have notice even T5 tubes from different Brands differ in current ratings thus making Ballast design suitable for one Brand become unsuitable for other Make.