Understanding Contactors: Types and Applications

A contactor is an electrical component that is used to control the opening and closing of a circuit. Depending on the operating principle and application requirements, contactors can be divided into various types. The following are some common types of contactors:

DC contactors: Suitable for DC circuits and are commonly used for low voltage and low power applications.

AC contactors: for AC circuits, usually capable of handling higher voltages and power.

Thermal Relay: Uses a thermal element to control the switching of a circuit. As current passes through the relay, the thermal effect of the current causes the thermal element to expand, which causes the switch to actuate.

Magnetic Relay: Uses a magnetic field generated by an electromagnetic coil to control the switching action. Typically used for higher current and power applications.

Solid-state relays: Use semiconductor elements (e.g. transistors, thyristors, etc.) to perform the switching function. Compared to traditional mechanical contactors, solid-state relays have no mechanical moving parts, longer life and no noise.

Time Relay: A contactor with a time delay function that switches a circuit after a set interval of time. Commonly used to control timing tasks and automated systems.

Heavy Duty Relay: Used to detect an overload in a circuit and break the circuit when a set current threshold is exceeded. Commonly used for electrical protection and overload protection.

These are just some of the common types of contactors, there are actually other special purpose contactors such as proximity switch relays, contactor combinations, etc. Each type of contactor has its own specific application scenario and advantages. Choosing the right type of contactor needs to be determined based on the specific circuit requirements and usage environment.

In semiconductor testing, contactors can also be referred to as the specialized socket that connects the device under test. In process industries, a contactor is a vessel where two streams interact, for example, air and liquid. See Gas-liquid contactor. For a person or thing that contacts, see Contact .

A contactor is an electrically-controlled switch used for switching an electrical power circuit.A contactor is typically controlled by a circuit which has a much lower power level than the switched circuit, such as a 24-volt coil electromagnet controlling a 230-volt motor switch.

Unlike general-purpose relays, contactors are designed to be directly connected to high-current load devices. Relays tend to be of lower capacity and are usually designed for both normally closed and normally open applications. Devices switching more than 15 amperes or in circuits rated more than a few kilowatts are usually called contactors. Apart from optional auxiliary low-current contacts, contactors are almost exclusively fitted with normally open ("form A") contacts. Unlike relays, contactors are designed with features to control and suppress the arc produced when interrupting heavy motor currents.

Contactors come in many forms with varying capacities and features. Unlike a circuit breaker, a contactor is not intended to interrupt a short circuit current. Contactors range from those having a breaking current of several amperes to thousands of amperes and 24 V DC to many kilovolts. The physical size of contactors ranges from a device small enough to pick up with one hand, to large devices approximately a meter (yard) on a side.

Contactors are used to control electric motors, lighting, heating, capacitor banks, thermal evaporators, and other electrical loads.