Thermal Overload Relay - Facts You Should Know About This Safety Device

Thermal Overload Relay - Facts You Should Know About This Safety Device


What is a thermal overload relay? A thermal overload relay is an electronic device used for thermal-mechanical protection for electrical circuits. It provides reliable protection against thermal overload or phase short-out in case of sudden power loss. It relives the overload condition by restoring the thermal supply and relieving the circuit from thermal damage. Relays are used for thermal overload protection in thermal-mechanical control systems, such as bus thermal motors, thermal control panels, and thermal switch contacts.


What are the applications of  The thermal overload relay is widely used in industrial applications to provide thermal-mechanical safety. It relives or replaces thermal contacts in thermal motors; controls thermal expansion and contraction; transfers alternating current (AC) through thermal control contacts; and provides protection against short-circuits and overload at the point of load separation. These relays allow the thermal mass to move smoothly without any jump or period of heating and cooling. They work with temperature compensation, overload, and temperature level changes.


The primary function of thermal overload relays is to protect the overload from heating up the supply circuit. The safety switch of the device can be set in either closed or open position according to the power supply circuit design. In order to provide temperature-relief, the relaying elements are designed with contacts that are placed on different points along the circuit. This arrangement allows the temperature-relief capacity of the device to be adjusted. The output of the device then causes the output voltage that is needed by the circuit.


How do thermal overload relays work? Before understanding how thermal overload relay  work, it is important to understand how thermal conductors work. The operation of this device starts by conducting a certain amount of motor current through the contacts. When the conductors heat up, the contactors short out. This causes the engine to slow down or to fail. When the test button is pressed, the relay automatically conducts a check of the complete circuit and stops the process when the temperature is verified.


The thermal overload relays use two types of controls. One type is a constant current source (CCS) that is used to control the speed of the motor current while the other type uses a pulse width modulation (PWM) to change the pulse width of the electrical current. Both types of controls are usually controlled through a four-position stop button. When the stop button is pressed, the current is suddenly reduced to zero and the motor current starts up.


If the thermal overload relay is mounted directly to the windings, it is called a direct mounted relaying unit. If the device is mounted indirectly, on the shaft of the windings, it is called a mounted indirect relaying unit. Both types of overload relays can be installed on shafts that are nearly identical so that they will share the same cooling requirements. However, the use of identical units will decrease the chances for them to properly protect your vehicle from overheating.


The thermal overload relay works in an entirely different way than a simple electronic overload protector does. The thermal overload relay uses a separate device that contains both an electronic circuit and also an accumulator. The electronic circuit is placed between the two elements. When the two elements fail to contact with each other, the stop switch will activate the interrupting current in order to cancel the short-circuit. This is done so that the motor will shut down before any damage occurs to the electrical components.


These are some important facts about thermal overload relays you should know. These safety protection devices are designed to protect you and the people around you from overheating. They can be used with both, electronic and physical overloads. They are also easy to install so you will not need anyone's help to install it. You can also reset and avoid the risk of overheating in case one of the circuit breakers or the interrupting current fails to stop the machine.