What is the difference between a relay and a contactor?
2 Answers
The essential difference between a relay and a contactor lies in the load they can handle. A contactor is designed for larger current capacities, while a relay is for smaller ones. Additionally, contactors are used in main circuits, whereas relays are employed in control circuits. Below is an introduction to the functions of relays and contactors: Functions of a contactor: Used to connect and disconnect larger current signals, driving power equipment such as motors. Functions of a relay: Used for signal conversion, serving as an interface for control signals between devices of different voltage levels. Its contacts generally have a smaller load capacity and are used to drive electrical components like contactors.
Although both relays and contactors are used to control circuits, they have fundamental differences. From the perspective of actual automotive circuit repairs: a relay acts like a transfer station, using weak current to control strong current, such as controlling low-power devices like car lights. They are small in size, simple in structure, and typically have only one set of contacts. Contactors, on the other hand, are specifically designed to handle high currents, such as motor drives in electric vehicles. They come with arc suppression devices to prevent contact burnout, have a more robust and durable structure, and feature dust-proof housing designs. Their design purposes differ from the outset—relays protect delicate circuits, while contactors withstand frequent switching of heavy loads. Therefore, if a relay in a car fails, it can be replaced for just a few dollars, but a faulty contactor may require disassembling major components.
