Contactor Overload Relays

All electric motors have a lifespan, and to keep them running efficiently and safely they must be protected. One of the main causes of failure is electrical overload, sometimes called overcurrent. When a motor draws more current than it is designed to handle, it causes the temperature to build up, resulting in overheating. This damages motor windings and coils. It is important to protect the motor and its circuit, and this is where the use of overload relays with contactors can help.

What Is Overload Protection?

Overload is where a motor draws a high current above its rated value for an extended amount of time. Overload causes motor overheating, causing damage. To prevent this from happening, devices such as contactor relays are specifically designed for industrial control motor protection. They are used with contactors as part of a motor starter or in a control panel or centre.

What Are the Different Types of Contactor Overload Relays?

Motor protection devices can be classified into two main types, which are thermal and electronic. Thermal overload relays utilise a bi-metallic strip that bends due to heat generated by a heating element carrying the motor current. When excessive current passes through the heating element, the bi-metallic strip bends enough to trigger a mechanism, opening the N/C (Normally Closed) contacts. This interrupts power to the contactor's control circuit, stopping the motor. Thermal overloads usually offer an adjustable current range as well as a manual or automatic reset option. They are a cost-effective and robust solution for basic motor protection.

Electronic overload relays don't have a bi-metallic mechanism. Instead, they use components such as current transformers (CTs) or temperature sensors to measure the motor’s load current electronically. They are generally more accurate and offer a wider current range than thermal devices. Electronic overloads often feature a selectable trip class, providing enhanced protection against single-phasing, overcurrent, and undercurrent conditions, and can offer communication capabilities for remote monitoring and control.

How Contactors with an Overload Relay Works

A contactor with an overload relay combines a contactor, which is a heavy-duty switch for controlling high-current loads, with an overload relay, which protects motors from overheating caused by overcurrent conditions. The overload relay can be adjusted to trip at a specific current level, allowing for customisation based on the motor's full load current rating. When an overload occurs, the overload relay trips, disconnecting the motor from the power supply. The contactor is responsible for the switching, whereas the overload relay protects the motor from damage.

Benefits of Using a Contactor with an Overload Relay

Contactor and overload relay combinations offer several key benefits:

• Comprehensive Motor Protection: Ensuring reliable operation and preventing costly motor damage from overloads and other fault conditions.
• Extended Motor Lifespan: Adjustable overload relays safeguard motors from overheating, which extends their lifespan and reduces the need for frequent replacements.
• Enhanced Safety: In the event of an overload, the overload relay disconnects the motor, preventing potential damage and improving overall safety.
• Cost-Effectiveness: Preventing equipment damage and reducing downtime results in significant cost savings over the long term.
• Easy Monitoring and Adjustment: Overload relays are relatively easy to monitor and adjust, allowing for flexible configuration and adaptation to different motor applications.

Industrial Applications of Contactor Overload Relays

Adjustable overload relays are essential components in various industrial applications, ensuring the safe and reliable operation of motors and other electrical equipment. They are commonly used in the following:

Motor Control Systems

Contactor and thermal overload relay combinations are fundamental to motor control systems, providing reliable switching and overload protection for motors of all sizes, from small fractional horsepower motors to large industrial motors driving heavy machinery.

HVAC Systems

In HVAC systems, contactors with overload relay units control and protect motors in fans, pumps, and compressors, ensuring efficient and safe operation, maintaining comfortable indoor environments, and preventing equipment failures that could disrupt climate control.

Pump and Compressor Control

Overload relays with contactors control and protect pumps and compressors in various industrial applications, preventing damage from overloads and ensuring reliable operation in critical processes like water distribution, air compression, and refrigeration.

Conveyor Belt Systems

Contactor and overload relay combinations are often installed in conveyor belt systems to control and protect motors, ensuring smooth and efficient material handling in various industries.

Electric Vehicle Charging Stations

At electric vehicle charging stations, overload contactors can be used to protect charging equipment and ensure safe operation during charging sessions, preventing damage from excessive current draw and ensuring the safety of both the charging equipment and the vehicle.

Industrial Lighting Systems

Contactor relays are used in industrial lighting systems to control and protect high-intensity discharge (HID) lamps and other lighting loads, ensuring efficient and reliable lighting while preventing damage to expensive lighting fixtures.

Power Distribution Panels

Contactor and overload relay units are commonly found in power distribution panels to control and protect various circuits and loads, providing a central point for managing and safeguarding electrical distribution throughout a facility.

Water Treatment Plants

Thermal contactors and overload relays can be used to control and protect motors in pumps, filtration systems, and other equipment, ensuring the continuous and reliable operation of essential water treatment processes.

Manufacturing and Production Lines

Contactors with overload relay combinations are essential in manufacturing and production lines to control and protect motors in various machines and equipment, ensuring smooth and efficient production processes and preventing costly downtime due to motor failures.

Cranes and Lifting Equipment

Adjustable overload relays are used in cranes and lifting equipment to protect motors from overloads and ensure safe operation when lifting and moving heavy loads, preventing damage to the motor and ensuring workplace safety.

Agricultural Machinery

Contactor and overload relay combinations are used in agricultural machinery to control and protect motors in pumps, irrigation systems, and other equipment, ensuring reliable operation and preventing costly downtime that could disrupt farming operations.

Oil and Gas Industry Equipment

In the oil and gas industry, adjustable overload relays protect motors and equipment in drilling rigs, pipelines, and refineries, ensuring safe and reliable operation in hazardous environments and preventing costly damage to critical equipment.

Welding Machines

Contactor relays are commonly used in modern welding machines to control the high currents required for welding processes and protect the equipment from overloads, ensuring safe and efficient welding operations and preventing damage to the welding machine.

Industrial Fans and Blowers

Thermal contactors are often utilised to control and protect motors in industrial fans and blowers, ensuring efficient ventilation and air circulation in various industrial settings, maintaining air quality, and preventing equipment failures that could disrupt critical processes.

Chemical Processing Plants

Contactor and overload relay combinations can be used to control and protect motors in pumps, mixers, and other process equipment, ensuring safe and reliable operation in potentially hazardous environments and preventing costly downtime or accidents.

Trusted Adjustable Overload Relay Manufacturer, Supplier & Distributor in Malaysia

RS is your trusted source for adjustable overload relays in Malaysia. As a leading manufacturer, supplier, and distributor, we offer a wide selection of high-quality contactor and thermal overload relays from top brands like Schneider Electric, Siemens and ABB. Our adjustable overload relay prices also cater to diverse budgets. Buy your adjustable overload relays from RS and experience quality, reliability, and expert advice.

Buy Adjustable Overload Relays Online from RS

Get your contactor and thermal overload relays online, along with other automation and control gear, like photoelectric sensors and level sensors, to enhance your industrial control systems. We offer competitive prices and a seamless online ordering experience. Enjoy fast, nationwide doorstep delivery. For detailed delivery information and fees, visit ourDelivery page.