What Is an AC Contactor? Your Essential Guide to This Electrical Workhorse

The best-performing AC contactors are referred to as electrical workhorses because of their unparalleled reliability and strength, as well as for how they have the ability to control high-power electrical loads in various industrial applications. 

In particular, they act as switches for such loads, enabling the safety and the efficiency of operations of equipment like motors, compressors, HVAC systems, and so much more.

Also pertained to as “the heart of electrical control,” this type of contactor is an essential component in various electrical systems. What are the things you should know about your AC contactor? Find out in this guide that will be discussing the following points: 

– Defining AC contactors and how they are different from relays

– How do AC contactors work? What are their key components?

– Why are AC contactors important? 

– Common applications of AC contactors

Defining AC Contactors and How They Differ From Relays

What is an AC contactor? Simply put, industrial AC contactors are electromechanical switching devices that are designed to switch AC loads on and off. More often than not, these tools are used to switch high-current AC loads.

Comparing this with a relay is like comparing an apple to an orange. While they are both switches operating in electromagnetic processes, they differ significantly in their applications, load capabilities, and design features.

Particularly, contactors are made for higher-power industrial applications, usually for the management of bigger currents, as well as voltages, whereas relays are typically used for low-power control circuits. In other, the two are generally polar opposites. 

The AC Contactor Working Principle

It’s All About Electromagnetism

Electromagnetism is the dynamics within AC contactors. So, basically, its working principle involves electromagnetic forces in cooperation with spring forces to make and break the connection between your source and your load.

That being said, once the coil is energized with low voltage, it generates a magnetic field and attracts the armature, causing movement in the contacts, then completing the circuit. You will understand those a bit better as you get to know the components up next.

What Are the Components at Play?

Here are the components working synergistically to make the electromagnetism a possibility once the contactor runs:

• Coil, or electromagnet, or solenoid: Known by these three terms, they act as the control switch. It’s wound with a certain number of turns of insulated wire, which could be energized with either AC or DC voltage.
• Armature: Another pivotal component in the contactor’s operations, this is typically made of a highly permeable magnetic material, designed so it quickly responds to the changes in the magnetic field. Once the coil is energized, this armature is pulled toward the coil’s center, overcoming the resistance of a return spring, essential to actuate the main contacts.
• Contacts (Main power contacts and auxiliary contacts): These contacts are responsible for the connection and interruption of your main circuit. Different from the auxiliary contacts which are for support, the main contacts consist of both static and moving sub-components.
• Frame, housing, or enclosure: This stands for the covering that provides insulation and protection to the coil and the contacts. 

TeSys Giga contactors

Manufacturer: Schneider Electric
Model: LC1G
Category: Control motors up to 800 A (450 kW/400V) or switch lines up to 1100A

View Product

The Importance of AC Contactors

What is the purpose of an AC contactor? From acting as the remote control to managing load, this equipment has several uses. 

Remote Control

These tools enable industries to switch high-powered circuits from a safe distance, minimizing the need to directly interact with live electrical components. The importance of this is that safety is enhanced. At the same time, industry managers will also be able to control from central panels or even remotely, thanks to networked systems.

Automation

An AC contactor is a key component in automation, too. They are easily integrated into programmable logic controllers and motor control centers, paving the way for the seamless control of machines, conveyors, and other automated equipment. Thus, the efficiency and precision of complex processes are duly guaranteed.

Safety

Furthermore, this equipment also provides the best of isolation in-between your control and power circuits, downgrading the risks of electrical shocks.

You may also connect them with emergency stop switches to enable the instant disconnection your high-risk, hazardous equipment during faults or emergencies.

Load Management

As your AC contactor control motors, lighting systems, heating units, and other resistive or inductive loads, they help in the effective management of electrical loads. Therefore, mishaps and issues in the operations are kept at bay. 

Common Industrial Applications

AC contactors are implemented in the following:

• Motor control in industrial machinery
• HVAC systems
• Lighting control in large buildings
• Heating elements
• Switchboards, and so much more

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