In the field of electrical engineering, contactors play a crucial role in controlling the flow of electricity within circuits. These electromechanical devices are essential components in various applications, from industrial machinery to residential HVAC systems. Understanding how contactors work and their different types, such as auxiliary contactors and electric contactors, is fundamental to comprehending their functions and applications.
How Contactor Works?
At its core, a contactor is a switch designed to handle large electrical currents. It consists of a coil, contacts, and an enclosure. When an electrical current passes through the coil, it creates a magnetic field, which attracts the contacts, closing the circuit and allowing electricity to flow. When the coil is de-energized, the contacts open, interrupting the circuit and stopping the flow of electricity.
Contactors are commonly used in applications where manual control or remote operation of electrical systems is required. They can handle high voltages and currents, making them suitable for switching heavy loads such as motors, heaters, lighting circuits, and power distribution systems.
Types of Contactors
Electric Contactors
Electric contactors are the standard type of contactors used in most applications. They consist of a coil, contacts, and an enclosure made of durable materials such as metal or plastic. Electric contactors are available in various sizes and configurations to accommodate different voltage and current ratings. They are typically controlled by switches, relays, or programmable logic controllers (PLCs) and are commonly found in industrial machinery, HVAC systems, elevators, and other electrical systems.
Auxiliary Contactors
Auxiliary contactors, also known as auxiliary contacts or auxiliary switches, are additional components that are often used in conjunction with electric contactors. Unlike electric contactors, which control the flow of electricity directly, auxiliary contactors are used to provide feedback or auxiliary functions, such as signaling, interlocking, or controlling other devices.
Auxiliary contactors are typically mounted on the side or top of the main contactor and consist of one or more sets of contacts. These contacts are mechanically linked to the main contacts of the contactor, so they open and close simultaneously. Auxiliary contactors can be normally open (NO), normally closed (NC), or changeover (CO), depending on the specific application requirements.
Differences Between Auxiliary Contactors and Electric Contactors
While both auxiliary contactors and electric contactors serve important roles in electrical systems, they have distinct functions and characteristics:
1. Functionality:
- Electric Contactors: Electric contactors are primarily responsible for controlling the flow of electricity within a circuit. They open and close the main circuit to enable or interrupt the flow of current to the load.
- Auxiliary Contactors: Auxiliary contactors, on the other hand, provide auxiliary functions such as signaling, interlocking, or controlling other devices. They do not directly control the flow of electricity but instead provide feedback or additional control signals based on the status of the main contactor.
2. Configuration:
- Electric Contactors: Electric contactors consist of a coil, contacts, and an enclosure. They are available in various sizes and configurations to accommodate different voltage and current ratings.
- Auxiliary Contactors: Auxiliary contactors are additional components mounted on the main contactor. They consist of one or more sets of contacts that are mechanically linked to the main contacts of the contactor.
3. Application:
- Electric Contactors: Electric contactors are used in applications where direct control of electrical loads is required, such as starting and stopping motors, controlling heating elements, or switching lighting circuits.
- Auxiliary Contactors: Auxiliary contactors are used in conjunction with electric contactors to provide auxiliary functions such as signaling when the main contactor is energized or de-energized, interlocking to prevent simultaneous operation of conflicting circuits, or controlling other devices based on the status of the main contactor.
Conclusion
In summary, contactors are essential components in electrical systems, providing reliable control of electrical loads in various applications. While electric contactors serve as the primary switches for controlling the flow of electricity, auxiliary contactors offer additional functionality such as signaling, interlocking, or controlling other devices.
Understanding the differences between these two types of contactors is crucial for designing and implementing effective electrical systems that meet specific application requirements. So, whether you’re starting a motor, switching a lighting circuit, or controlling a complex industrial process, knowing how contactors work and their different types ensures safe, reliable, and efficient operation of electrical systems.