The Purpose of a Ballast Resistor

Fixed Resistors

• Ballast resistors come in a variety of types. The most common type is those used in electrical lighting devices, such as LED lighting. These fixed resistors are designed to limit the amount of current into these devices, which are inherently low-voltage devices in the first place.

Automobiles

• Fixed resistors aren't limited to use in lights. Some are used in automobile engines. These are sometimes used in the ignition coil system of an automobile to limit the amount of voltage to the various engine parts after it has been started. This prevents excess wear and tear on the engine because it operates on a lower voltage than would otherwise be supplied. Also, the resistor plays the opposite role during the starting process by supplying additional power to the automobile in order to allow the engine to crank at a faster rate. These types of resistors are generally found only in older automobiles.

Variable Resistors

• Some ballast resistors are self-regulating variable resistors that adjusts its resistance to the electrical current based on how high the current is to begin with. If current levels drop while in operation, the resistance of the ballast resistor drops with it. These types of resistors are best in electrical devices that require a large amount of voltage or where there are significant current fluctuations to account for. This provides more flexibility with the types of devices that can be used in various types of electrical applications where high voltage may prove to be a threat to the electrical device.

Electronic Ballasts

• Some devices use electronic ballasts. Electronic ballasts limit the amount of current flowing into a device, but usually allows the frequency to remain high enough to operate high-intensity devices such as fluorescent lamps. These are generally considered to be high-efficiency ballasts in that the lights are able to operate at high intensity, while the ballast provides significant resistance.