Devices that provide the proper voltage and current needed to operate gas discharge lamps such as fluorescent and HID are called ballasts. Ballast limits the current transmitted to gas discharge lamps. In this way, it prevents the lamp from deteriorating by pulling the high current.
Ballast is the mechanism that controls how much electrical current goes from the power source to the lamp. The ballast’s duty is not to protect the lamp by limiting the current only. It also provides the ballast for the voltage needed to ignite the lamp.
Gas discharge lamps need high voltage when first switched on. Under high voltage, an electric arc is formed and triggers the gases in the lamp. After the arc is formed, ballast tries to limit the current by reducing the voltage. In this way, the light output of the lamp is fixed and protected. If the current is not limited in the lamps with gas discharge, the lamp is heated and malfunctioned uncontrollably. Keeping the temperature in a safe range is extremely important for lamp life.
The ballast is divided into the magnetic ballast and electronic ballast.
Magnetic ballast has a simple design. A transformer is used with copper winding wire. The length and the thickness of copper wire determine the output current of ballast. Magnetic ballasts are big and heavy structure.
Electronic ballasts use electronic circuit elements to control the output current. Current can be managed sensitively with electronic ballasts. According to magnetic ballasts, electronic ballasts are smaller and lighter. In addition to this, it has higher electrical efficiency.
Electronic ballasts are used in almost all modern applications. Because, electronic ballasts reduce energy consumption compared to magnetic ones, allowing energy to be used more efficiently. Electronic ballasts can also provide control of the output current so that brightness can be increased and reduced at the time of need.
In the lighting systems used in magnetic ballasts, it is possible to change the ballasts in electronic ones.