There is a positive feedback relationship between the discharge current of the fluorescent tube and the on-resistance: when more current flows into the fluorescent tube,T8 tube light more gas is ionized,T8 tube light so that the on-resistance in the tube is continuously reduced,T8 tube light which will cause more current Into the fluorescent tube.
If the fluorescent tube is directly connected to a fixed voltage power supply,T8 tube light the fluorescent tube will be burned quickly due to the rising current. Therefore,T8 tube light an auxiliary circuit is required to control the current entering the fluorescent tube to a fixed level,T8 tube light and this current control circuit is usually It is called a ballast. The ballast is actually an inductance. When the on-resistance drops to a very low level,T8 tube light the fixed inductance and copper loss of the ballast make the on-current approximate to a constant value and start to work stably.
Ballasts are divided into inductive ballasts and electronic ballasts. Inductive ballasts need to be matched with a small element called Starter (commonly known as “Star”) to make the pressure difference between the filaments reach the desired level. The fluorescent tube is sufficient to discharge,T8 tube light but the electronic ballast does not need a starter,T8 tube light because the start-up work is already contained in the ballast.