The ballast is an iron core inductive coil. The function of the inductance is to cause changes in magnetic flux when the current in the coil changes, thereby generating induced electromotive force. Since its direction is opposite to the direction of the current, it hinders the current change. The ballast can be composed of inductors, resistors, capacitors and leakage transformers independently, or can be composed of these devices or a combination of electronic components. In practical applications, the function of the ballast is not limited to the ballast itself, but other functions or devices required in the circuit are often included in the ballast.
