What is a Ballast
Ballasts are used in all discharge lamps, it is used to limit the amount of current in the lamp and it provides a better starting voltage. There is low and high power factor ballast, the low power factor ballast is cheap and inefficient while the high power factor ballast has better efficiency.
It is an integral component of the lighting system it has a direct impact on the light output.
What is a Ballast factor
A ballast factor is the ratio of lamps light output using the selected ballast, compared to the lamps rated light output which is listed in lamp catalogs. Mostly the general-purpose ballasts have a ballast factor which is less than one while special ballasts have ballast factor greater than one.
What are the major functions of a Ballast
- It provides higher starting voltage to the lamps because it needs higher voltage in the start than to operate
- It could match the line voltage to the operating voltage of the lamp
- It can limit the lamp current to prevent immediate destruction because the lamp impedance will decrease if the arc is struck.
Why do we need Ballasts
It is used in discharge lamps, an arc discharge lamp operates in negative resistance if the current flow continues in this conditions it will increase quickly and the lamp will be burned, so in order to control the current ballasts are used
Ballasts are used for the arc discharge, in these lamps the arc discharge is possible at a specified voltage, and this is provided by the open-circuit voltage of a ballast.
Ballast circuit types
Instant start ballast
It could start the lamp instantly with higher starting voltage, it is efficient too but it may affect the lamp life
It has a slight delay to start a delay of 0.5 seconds it will supply the starting current to heat the filament prior to the starting and continues during operation. It uses 2 to 4 watts more than an instant start ballast
Programmed rapid start
It also has a delay of 0.5 seconds to start, it also heats the filament by the starting current but cuts of during the operation
Types of Ballasts
There are two types of fluorescent ballasts they are magnetic and electronic ballasts
It is classified into
- Standard core coil
- High-efficiency core coil
- Cathode cut out or hybrid
Standard core coil is a core coil transformer which is inefficient to operate fluorescent lamps, the high-efficiency ballast upgrades the aluminum wiring and the lower grade steel of standard ballast with copper wiring and enhanced ferromagnetic materials
The cathode cut out ballasts are the high efficient ballast they incorporate electronic components that cut off power to the lamp cathodes after the lamps are lit. which could save the current
Mostly all full-size fluorescent application uses electronic ballasts, it can improve the fluorescent system efficiency by converting the 60HZ input frequency to a higher frequency and by doing this the lamp will only consume less power. By using electronic ballasts there won’t be any lamp flicker and dimming.
Some of the electronic ballasts can operate four lamps at a time