Thermal Overload Relay: A Comprehensive Guide

Overheating is a typical issue with electrical systems, particularly in industrial settings where high-power motors and other machinery are employed. The equipment may become damaged by overheating, and in severe circumstances, a fire may potentially break out. The usage of thermal overload relays stops this from occurring. Everything you need to know about thermal overload relay will be covered in this blog.

A Thermal Overload Relay: What Is It?

The purpose of a thermal overload relay is to safeguard electrical equipment against overheating. It works by keeping track of the equipment’s temperature and cutting off the power supply when the temperature rises above a certain point.

Motor control circuits frequently employ thermal overload relays. They serve as a safeguard against the engine overheating as a result of the extended operation or significant loads. Other pieces of equipment that might overheat, such as transformers, generators, and other electrical devices, also employ them.

A Thermal Overload Relay: How Does It Operate?

Thermal expansion is the basis for how thermal overload relay operate. A bimetallic strip within the relay swells when heated. When the bimetallic strip grows over a particular point, it comes into contact with a tripping mechanism, which opens the contacts of the relay. The connectors are made to cut off the equipment’s power supply, preventing overheating.

The manufacturer sets a certain temperature range for the bimetallic strip to be calibrated. The bimetallic strip stretches and the contacts of the relay open when the equipment’s temperature rises over this threshold, cutting off the power supply to the device.

Thermal Overload Relay Types

• Thermal overload relays come in two primary categories:
• Thermal overload relay of the bi-metallic strip type
• Thermal overload relay of the electronic kind
• Thermal Overload Relay of the Bi-metallic Strip Type

This is the standard model of the thermal overload relay, which measures temperature using a bimetallic strip. The bi-metallic strip is composed of two distinct metals with various thermal expansion coefficients.

The bimetallic strip expands as the equipment’s temperature rises, and this movement is what triggers the tripping mechanism.

Relay for Thermal Overload of Electronic Type

This kind of thermal overload relay measures temperature using electrical components. In comparison to the bi-metallic strip kind, it is more accurate and trustworthy. It detects temperature using a thermistor or thermocouple and then sends a signal to the tripping mechanism to cut off the power source.

Benefits of Thermal Overload Relays

• Protection from Overheating
• Thermal overload relays shield electrical equipment from overheating and shield it from harm.
• Thermal overload relays are more affordable than other types of safety equipment.
• Thermal overload relays are simple to install and don’t need any specialized tools or expertise.
• Thermal overload relays need little upkeep and can function for many years before needing to be replaced.

Conclusion

Relays that safeguard against thermal overload are a crucial component of electrical systems. They guard against overheating, which can harm equipment or possibly start a fire. The bi-metallic strip type and the electronic type are the two primary varieties of overload thermal relay.