1. The effect is different

The primary function of relay is signal detection, transmission, conversion or disposal. Its circuit current is generally small, which is generally used in control circuit to control weak signal.

The primary function of contactor is to connect or disconnect the main circuit. The main circuit refers to whether a circuit works or not is marked by whether the circuit is connected or not. The concept of main circuit corresponds to control circuit. Generally, the current passing through the main circuit is larger than that of the control circuit.

Contactors with large capacity are usually equipped with arc extinguishing cover. Generally, the contact capacity of relay will not exceed 5a, the contact capacity of small relay only needs 1A or 2a, and the smallest contact capacity of contactor is 9A; generally, the contact of contactor has three pairs of main contacts (main contacts are normally open) and several pairs of auxiliary contacts.

The contact of relay is usually not divided into main and auxiliary contacts; the contact of relay is sometimes set in pairs, that is, the normally open contact and normally closed contact are combined together, while the contactor is not set in pairs; for specific needs, the relay will be combined with other equipment into time relay, counter, pressure relay, etc., with additional functions, while the contactor generally does not.

2. Different opening and closing contacts:

In addition, the contactor is used to connect or disconnect the load with high power. In the (power) main circuit, the main contact can have interlocking contact to indicate the opening and closing of the main contact. The relay is usually used in electrical control circuit to expand the contact capacity of micro or small relay to drive larger load.

The contact of a contactor that can be turned on or off, as with a relay. Generally, relays have many open and close contacts. Of course, relays can complete some special functions, such as logic operation, by proper connection.

3. There is one arc extinguishing device and one is not

In fact, the most important difference between contactors and relays is that contactors have arc extinguishing devices, while relays do not.