When designing equipment with switching functions, most engineers find that switching high currents and high voltages is a major problem. A solid-state solution may be possible, but it’s complex and expensive. One sure approach is to use a contactor. High-voltage, high-current contactors are available that can solve even the toughest of switching problems.
Contactor Basics
A contactor is just a heavy-duty mechanical relay for switching high voltages or high currents, or both. A common application is the contactor in every car and truck that starts the engine. When the ignition switch is turned or button is pressed, 12 V from the battery is applied to a contactor. It contacts then close, connecting the 12-V battery to a starter motor that spins the engine and starts the vehicle.