Magnetic Contactor: Function, Symbol, How it Works, and Components

Table of Contents

What is a Magnetic Contactor?

A magnetic contactor (known in Indonesian as "kontaktor magnet") is an electromechanical device used to control the flow of electricity in electrical equipment such as electric motors, capacitor banks, etc.

A magnetic contactor is a magnet-based switch. This device operates when a magnetic force is generated. The magnet functions to connect and disconnect the contacts.

The contacts in a magnetic contactor consist of two types: main contacts and auxiliary contacts. The main contacts function to connect and disconnect the electrical flow in electrical devices, while the auxiliary contacts function to control the main contacts.

When selecting a contactor, you need to consider the following specifications:

1. Operating voltage
2. Electrical power
3. Current capacity
4. Number of contacts

Functions of Magnetic Contactors

A magnetic contactor is an electromechanical component used to control electrical flow in power circuits, especially in electric motors, heaters, lights, and other electrical equipment. Here are its main functions:

1. Connecting and Disconnecting Electrical Circuits

Magnetic contactors work like electromagnetically operated switches, allowing remote control of electrical loads (ON/OFF).

2. Electric Motor Control

Used to control the operation of 3-phase or single-phase induction motors, such as start/stop, forward/reverse (when combining two contactors).

3. Protection

Some contactors come with thermal overload relays to cut off current during overloads, preventing motor damage.

4. System Automation

Can be integrated with PLCs (Programmable Logic Controllers), sensors, or timers to automate industrial processes.

5. Reducing Current Load on Manual Switches

Contactors are designed to handle high currents, so control switches (like push buttons) only need to carry small currents to the contactor coil.

6. Star-Delta Starter Applications

Used in star-delta motor starting circuits to reduce high starting currents.

How Magnetic Contactors Work

Contactors work by utilizing the electromagnetic system generated in the coil. The coil, made from conductor windings, creates a magnetic field when electric current is applied.

This generated magnetic field moves the main contacts to connect with the fixed contacts. When the current to the coil is cut off, the magnetic field disappears. This happens because the coil contains a spring that automatically opens the contacts again.

Components of Magnetic Contactors

Magnetic contactors have several internal components, each with its own function and purpose.

1. Main contacts: Consist of 3 NO (Normally Open) contacts labeled with numbers 1-2, 3-4, 5-6. Main contacts are typically larger and thicker to handle relatively high electrical currents (load currents).

2. Auxiliary contacts: Have smaller and thinner construction, only capable of carrying relatively small currents. These include Normally Close (NC) and Normally Open (NO) contacts.

3. Contactor coil: This component consists of windings and is electromagnetic. When energized, the coil generates a magnetic field that changes the contactor's contacts from normally closed to normally open or vice versa.

Benefits of Using Magnetic Contactors

Using magnetic contactors in electrical systems offers several significant advantages:

• Improved Electrical Safety: Current to the motor passes through the contactor first, providing extra protection and enhancing electrical system safety.
• Easy Control: Contactors can be easily controlled by other electronic devices like relays or programmable logic controllers (PLCs), offering system flexibility.
• Simple Maintenance: Maintaining contactors is easier than manual switches. Their components are designed for durability and easy replacement.
• Minimized Spark Potential: Contactors produce fewer sparks compared to manual switches, reducing fire risks and component damage.
• Remote Control: Contactors allow motor control from a distance without requiring many large cables, making installations neater and more efficient.
• Cost-Effective: Contactors are generally cheaper for high-current applications compared to equivalent switches.

Tips for Choosing Contactors

To ensure optimal performance, it's important to select contactors with appropriate specifications. Consider the following:

• Coil Voltage: Determine the coil voltage (380VAC, 220VAC, or 24VDC).
• Motor Current: Check the motor's ampere rating (on its nameplate) and choose a contactor with a slightly higher ampere capacity.
• Application: Determine whether the contactor will be used for motor operation or lighting installations, as they have different requirements.

Additionally, choose high-quality contactors from experienced electrical manufacturers to ensure reliability and longevity.

This concludes our article about magnetic contactors from Electrical.Kelasteknisi.com. We hope you find it useful.