# How is motor contactor rating determined?

Contents

Size of Main Contactor = 100%x6 = 6 Amp. Making/Breaking Capacity of Contactor = Value above Chart x Full Load Current (Line). Making/Breaking Capacity of Contactor = 8×6 = 52 Amp.

## How do you select a contactor for a motor?

Power contactors have 3 poles or 4 poles versions. You should select the suitable contactor according to the number of phases of the load. For example, if you want to control a 3 phase motor, you should use 3 pole contactor. If you want to disconnect the neutral, your choice should be 4 pole version.

## What is rating of contactor?

NEMA contactors for low-voltage motors (less than 1,000 volts) are rated according to NEMA size, which gives a maximum continuous current rating and a rating by horsepower for attached induction motors. NEMA standard contactor sizes are designated 00, 0, 1, 2, 3 to 9.

## How do I choose a power contactor?

When selecting a contactor, please make sure that the contactor’s rated current is specified for the AC-3 load type. Ensure that you are looking at the right table. You can see the rated current for the AC-3 load is lower than the rated current for the AC-1 load.

## What is AC1 and AC3 rating of contactor?

The difference between AC1 and AC3 contactors is AC1 contactors are used for general purpose resistive loads but AC3 contactors are used for high inductive, squirrel cage motor switching. The rating of AC3 is lower than AC1. Because AC3 switches high inrush currents.

## Is contactor rating per pole?

Contactors are rated by designed load current per contact (pole),maximum fault withstand current, duty cycle, voltage, and coil voltage.

## How do you calculate contactor coil current?

First, the type of the AC contactor for the motor generally adopts the ac-3 series. Then, the working current of the motor is estimated: I=5.5*2=11A. At last, the working current of the AC contactor can be about: 11*1.5=16.5A.

How to Calculate AC Contactor Current Rating for Motor?

Rated Power Current ratings AC Contactor Model
15 kW 30A CJX2-4010

## How do I choose a contactor size?

As per above chart:

1. Type of Contactor = AC7b.
2. Size of Main Contactor = 100%X Full Load Current (Line).
3. Size of Main Contactor = 100%x6 = 6 Amp.
4. Making/Breaking Capacity of Contactor = Value above Chart x Full Load Current (Line).
5. Making/Breaking Capacity of Contactor = 8×6 = 52 Amp.

## How is star delta starter contactor rating calculated?

Main & Star-delta contactor calculation

1. Main contactor rating = 58%X Full Load Line Current = 7.96A.
2. Delta contactor rating = 58%X Full Load Line Current = 7.96A.
3. Star contactor rating = 33%X Full Load Line Current = 4.53A.

## How is contactor coil voltage selected?

Contactor Coil Voltage

You should next confirm the control voltage to be used to power the contactor. This can be the same as the line voltage, however often a lower voltage is selected for the contactor for safety purposes. Generally, coil voltages are 250V or below.

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## What is AC1 and AC2?

1)AC1– Non-inductive or slightly inductive rows. 2) AC2– Starting of slip-ring motors. 3) AC3– Starting of squirrel-cage motors and switching off only after the motor is up to speed. (

## What does AC1 mean on contactors?

AC-1 – This category applies to all AC loads where the power factor is more than 0.95. These are primarily non-inductive or slightly inductive loads, such as resistive loads. Breaking the arc remains easy with minimal arcing and contact wear.

## What is AC1 duty in contactor?

AC duty (Alternating Current) for Contactors:

AC-1: Such duty contactors are used in resistive loads such as heaters and electrical furnace. Non-inductive or slightly inductive loads are included which means the power factor of the load lie between 0.95 to 1.