Contactors

In simple terms, a contactor, contactor switch or contactor relay is a device designed for switching an electrical circuit on or off. They are part of the relay family, but the main difference is that a contactor is used in applications with higher current capacity is involved. Contactors are typically used for motors, lighting circuits, heating, and other electrical loads. A contactor can function on its own or as a power control device or as part of a motor starter.

RS Hong Kong offers a comprehensive range of high-quality electrical contactors from industry-leading brands including Schneider Electric, Siemens, Eaton, ABB, and Lovato. We also stock a selection of accessories used to enhance the function of the contactor including Contactor Overload Relays, auxiliarycontacts, mechanical interlocks, and much more. Overload Relays, auxiliarycontacts, mechanical interlocks, and much more.

How does a contactor work

Contactors are switches designed for high current load devices and can be controlled remotely. Unlike standard relays, they can handle more than 10 amperes and are used in large-scale control circuits. In addition, contactors feature high coil voltages and incorporate spring-loaded contacts that quickly open and close to assist with arc suppression, ensuring the contactor's ability to interrupt heavy motor currents with minimal damage over a longer life cycle. Contactors are versatile and used in basic light switches to complex applications such as controlling electromagnets.

Different types of contactors

There are various types of contactors, and each type will have its own set of specifications depending on your application.

AC vs DC contactors

AC contactors are typically used in applications where the current alternates direction. For residential purposes, 3-phase contactors--a specialised type of AC contactor--are used for optimising energy utilisation. They are also commonly used in industrial and commercial applications because they provide a more efficient power supply for large motors and heavy electrical loads.

On the other hand, DC contactors are used in applications where the current flows in a single direction, such as in battery-powered systems.

Different voltages of contactors

AC and DC contactors are available with coils designed to operate at various voltages to suit different applications. Typical coil voltages include 12V, 24V, 48V, 110V, 240V, 400V, and 440V.

Take note that the contactor coil voltage does not need to match the load voltage being switched. For instance, the coil voltage could be 24V DC, while the motor being controlled could be 400V AC.

Reversing vs non-reversing functionality

Reversing contactors are designed to change the direction of the motor's rotation, which is crucial in applications like conveyor belts, cranes, and other machinery requiring forward and backward motion. Meanwhile, non-reversing contactors are used in applications where the motor operates in a single direction.

AC3 and AC1 categories

AC contactors are divided into categories, with AC3 and AC1 being the most common. AC3 contactors control inductive loads that need frequent switching and high starting currents. AC1 contactors are for non-inductive loads with lower inrush currents, such as lighting and heating circuits.

Number of poles

The number of poles determines the contactor's ability to manage multiple circuits simultaneously. Common variants include 2-pole, 3-pole, and 4-pole contactors, with each pole representing a separate electrical contact. For more specialised applications, contactors with 8 or even 10 poles are available.

Contact configuration

Contactors are designed with various contact configurations to meet specific application needs. The configuration of the contacts affects how the electrical load is controlled and protected. When choosing a contactor, consider factors like contact type, coil voltage, and power ratings to ensure compatibility with your device or system.

IEC standards

At RS Hong Kong, our contactors are manufactured and tested according to International Electrotechnical Commission (IEC) standards. This compliance ensures that our contactors meet stringent safety, performance, and reliability criteria.

Applications of contactor relay

Contactor relays are versatile and essential components in various industrial applications. They provide reliable control and automation for numerous electrical systems. Here are some common industrial applications of contactor relays.

• Motor control: Contactor relays are used to start and stop motors in industrial machinery and equipment.
• Lighting control: A contactor relay manages large lighting systems in factories, warehouses, and commercial buildings.
• HVAC systems: A contactor relay controls heating, ventilation, and air conditioning systems in industrial and commercial settings.
• Pumps and compressors: A contactor relay operates pumps and compressors in water treatment plants, manufacturing, and other industrial processes.
• Conveyor systems: A contactor relay automates the operation of conveyor belts in production lines and material handling systems.

How to choose the right contactor switch for your needs

When choosing a contactor switch, consider the voltage and current requirements, number of poles, and contact configuration. Ensure the contactor can handle the electrical load and is suitable for your environmental conditions. More importantly, check for compliance with standards like IEC to guarantee safety and performance.

At RS Hong Kong, we provide high-quality contactor switches. Our wide range of products meets strict safety and performance standards, ensuring you find the right solution for your needs.

For added safety measures, please check out our comprehensive guide to workplace safety and industrial site safety here.

How to order contactors from RS?

At RS Hong Kong, we are the trusted supplier of high-quality contactor switches, relays, and other power supplies. Our wide range of products, including brands like Schneider Electric, Siemens, Eaton, ABB, and Lovato, meets strict safety and performance standards.

To order contactors from RS Hong Kong, visit our website and browse our catalogue. Follow the instructions to complete your purchase. You will receive an order confirmation email with your order details and delivery estimate.

We strive to provide excellent service to ensure a smooth and satisfactory shopping experience. If you need assistance, our customer service team is available to help with product selection and order placement.

How delivery works at RS Hong Kong

Ready to place your order? Get contactors and other supplies under our Automation & Control Gear line such as float switches and sounder beacons from our RS website. Check our ordering and delivery information below.

For same day delivery, orders must be placed on Monday through Friday before noon. Next day delivery is available for orders placed on Monday through Friday afternoons, as well as orders placed on Saturdays, Sundays, and Holidays, but only for Hong Kong stock.