# What Is Contactor And Types?

## What is the difference between a relay and a contactor?

Contactors are typically built for and used in 3-phase applications where a relay is more commonly used in single phase applications.

A contactor joins 2 poles together, without a common circuit between them, while a relay has a common contact that connects to a neutral position..

## What is a 4 pole contactor?

4 pole contactors are electrically controlled switches (relays) used for switching an electrical power circuit. … The physical size of contactors ranges from a device small enough to pick up with one hand, to large devices approximately a meter on a side.

## What is the difference between ac1 and ac3 duty contactor?

Difference between AC1 and AC3 contactors is AC1 contactor are used for less inductive loads such as resistive loads (the power factor of the load is near about 1) but AC3 duty contactors are used for high inductive, squirrel cage motors which will be off during the motor is running condition.

## What do the numbers on a contactor mean?

These auxiliary contacts (also called control contacts) each have an order number and a function number. The first number is used consecutively (order number) and the second number specifies the type of contact (function number).

## What’s a relay switch?

Relays are electric switches that use electromagnetism to convert small electrical stimuli into larger currents. These conversions occur when electrical inputs activate electromagnets to either form or break existing circuits.

## What is ac1 contactor rating?

AC-1 – This category applies to all AC loads where the power factor is more than 0.95. … AC-3 – This category applies to squirrel cage motors with breaking during normal running of the motor. On closing, the contactor makes the inrush current, which is about 5 to 7 times the rated full load current of the motor.

## What is NO and NC In Contactor?

Relays and contactors have two types of contacts, each suited for different applications: Normally open (NO) contacts allow current when the relay or contactor is energized. … Normally closed (NC) contacts allow current through when the relay or contactor is not energized.

## How many types of contactors are there?

The current carrying task of the contactor is done by the contacts. There are different types of contacts in a contactor namely, contact springs, auxiliary contacts, and power contacts.

## What is a magnetic contactor?

Magnetic contactors are a form of electrical relay found on most electrically powered motors. … They are detachable from a motor so that an operator may work with that motor; disassemble or maintain it, without the possibility of live current still passing through the device.

## How do you wire a 3 phase contactor?

How to Wire a Three-Phase ContactorShut off the power to the three-phase load. … Take additional black, red, and blue three-phase wire that is the same size as the supply wires and connect one end of these wires to the T1, T2, and T3 terminals on the contactor. … Connect the control circuit to the positive and negative control terminals of the contactor.

## What is difference between NO and NC?

NO is normally open i.e. the contacts are normally open and close when the switch is actuated. NC is normally closed i.e. the contacts are normally closed and open when the switch is actuated.

## What is NC contact?

A normally closed (NC) contact pair is closed (in a conductive state) when it, or the device operating it, is in a deenergized state or relaxed state. A normally open (NO) contact pair is open (in a non-conductive state) when it, or the device operating it, is in a deenergized state or relaxed state.

## Why do we need contactors?

Why are Contactors Used? Contactors are used for high power applications. They allow a lower voltage and current to switch a much higher power circuit, so they are generally larger and more heavy-duty than control relays, enabling them to switch higher power loads on and off for many thousands of cycles (Figure 1).

## Why use a relay instead of a contactor?

Relays are switching devices used in any control circuit for checking a condition or multiplying the number of contacts available. Contactors are switching devices used to control power flow to any load. Mainly used in control and automation circuits, protection circuits and for switching small electronic circuits.

## What is the function of contactor?

Function of contactor, generally used for connected and disconnected of electric current supply. Usually in use for applications: motors, heater, lighting or electric power distribution.

## What is 3phase contactor?

3 pole contactors are electrically controlled switches (relays) 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 220-volt motor switch. … 240V coil as standard.

## How is contactor overload tested?

So if any heater trips it breaks the voltage to the contactor and it de-engergises. So check out the contactor coil wiring, one tag should be wired via the contacts on the overloads. Once you have located this wire. Disconnect the power and do a continuity test on the heater switch.

## How is contactor size calculated?

Size of Main Contactor = 100%X Full Load Current (Line). Size of Main Contactor =100%x6 = 6 Amp. Making/Breaking Capacity of Contactor= Value above Chart x Full Load Current (Line).

## How do I choose a contactor?

In order to correctly select a contactor for your application, you will first need to consider the following points. Control circuit voltage e.g. 24VAC, 230VAC, 400VAC, 24VDC etc. Note: If AC then select correct supply frequency, if DC is low power consumption option needed?