#contactor relay

What is the relay used for ?

A relay is an electronic device used to control a high-power circuit using a low-power signal. It is essentially an electromagnetic switch that uses a small amount of current to control a larger current.

Relays are commonly used in various types of circuits, including:

Control circuits: Relays are often used in control circuits to turn on or off other components such as motors, lights, and valves. They are used in industries such as manufacturing, automation, and process control.

Automotive applications: Relays are used in cars to control various systems such as the starter motor, fuel pump, and headlights.

Protection circuits: Relays can be used in protection circuits to disconnect a circuit if an abnormal condition such as an overload or short circuit is detected.

Communication systems: Relays can also be used in communication systems to amplify and switch signals.

How Do We Differentiate a Contactor from Other Relays?

 Contactors can be described as a special-purpose type of relay that are intended for interrupting and establishing high-power circuits repeatedly. Contactors commonly have multiple contacts that are normally open, so that load power is shut off when coil is disconnected to power source. Contactors are switching devices for auxiliary and control circuits and are used to interlock, control and provide signals to switchgear panels as well as switching devices. Reasonably, the most frequent industrial use for contactors is for electric motors. Most of the integral horsepower motors, that are 1hp and above, are controlled with contactors.

 A contactor is a magnetically-operated device often used to control power that is above 5kW while the term “relay” is commonly associated with power below 5kW. A contactor can be a relay but a relay cannot be a contactor.

Relay Vs. Contactor

 Relay

Goes     “Click” when energized.

Switches     loads of lower wattage

Applications     include control circuitry

Generally     switches currents less than 10-15 Amperes.

Generally     switches voltages less than 240 VAC

Switches     AC or DC

Not     normally rated in horsepower.

Double     throw is typical (normally open and normally closed contacts in one unit).

Relay     coils are AC or DC, but tend to be 5-24VDC with back emf power diodes to     protect relay control electronics.

The     buck just gets passed here. Relays tend to be "pilot" control     devices, controlling more powerful contactors.

 Contactor

Goes     “Clunk” when energized.

Switches     loads of higher wattage

Applications     include power circuits (from electric motors to a country's main power     grids).

Generally     switch currents above 10-15 Amperes.

Generally     switch voltages 120 VAC or greater.

Switch     AC or DC, resistive or inductive loads, but generally switch AC Loads.

Usually     includes a horsepower rating.

Single     throw is the norm (either normally open or normally closed contacts, rarely     both).

Usually     A.C. powered coils (24 VAC for safety- interlocked with EPO or EMO, and     Panel open interlock switches; 120-240VAC for simplified operations are     typical applications)

The     buck stops here. Contactors are the real deal. They can be controlled by     smaller, less powerful relays.