Thermal Overload Relays

ATO as a Chinese supplier provides JR28 and JR36 two series 3 phase thermal overload relay. 25A, 32A, 36A, 63A, 93A, 160A rated current can be chosen. Thermal overload relay is equipped with a flame retardant shell to withstand wear and high temperature.

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Thermal Overload Relays

Thermal overload relay is used for overload protection of motor or other electrical equipment and electrical lines. As a type of overload protection component, thermal relay has wide applications in production due to its small size, simple structure and low price.

ATO as a supplier provides JR28 and JR36 two series 3 phase thermal overload relay. 25A, 32A, 36A, 63A, 93A, 160A rated current can be chosen. The 3 phase thermal overload relay is equipped with a flame retardant shell to withstand wear and high temperature. 3 phase thermal relay is often used in AC motors.

JR28 3 Phase Thermal Overload Relay

JR28 3 phase thermal overload relay rated operating current is available at 25A, 36A and 93A. Ambient air temperature between -5 ℃ and 40 ℃.

JR26 3 Phase Thermal Overload Relay

ATO thermal overload relay features overcurrent and phase-failure protection functions. Optional current 20, 63, 120 Amps, rated insulation voltage 690V.

Thermal Overload Relay Function:

Under normal circumstances, turn on and off the no-load and load current in the high-voltage circuit. When the system fails, it can cooperate with the protection device and the automatic device to quickly cut off the fault current to prevent the accident from expanding, thereby ensuring the safe operation of the system. Thermal relay generates heat by the current flowing into the thermal element, which deforms the bimetallic sheets with different expansion coefficients. When the deformation reaches a certain distance, it pushes the connecting rod to act to disconnect the control circuit, thereby causing the contactor to fail. The main circuit is disconnected to realize the overload protection of the motor.

How to Select Thermal Overload Relay?

In principle, the ampere-second characteristic of the thermal overload relay should be as close as possible or even coincide with the overload characteristic of the motor, or under the overload characteristic of the motor. And at the same time, the thermal overload relay should not be affected (no action) at the moment of short-term overload and startup of the motor.
When thermal overload relays are used to protect motors in long-term work or intermittent long-term work, they are generally selected according to the rated current of the motor. For example, the setting value of the thermal overload relay can be equal to 0.95-1.05 times the rated current of the motor, or the median value of the setting current of the thermal overload relay can be equal to the rated current of the motor, and then to adjust.
When the wholesale thermal overload relay is used to protect the motor with the repeated short-time operation, the thermal overload relay has only a certain range of adaptability. If there are many operations in a short time, a thermal overload relay with a fast saturation current transformer should be used.
As a supplier, ATO suggests that the special working motor with positive and reverse rotation and frequent on and off, the thermal overload relay should not be used as an overload protection device but should be protected by a temperature relay or thermistor embedded in the motor winding.

Thermal Overload Relay in Overload Protection

Thermal overload relay is mainly used for circuit overload protection. Its working principle is that after overloading the current overheating element, the bimetallic sheet is heated and bent to push the action mechanism to drive the contact action, so that the circuit is disconnected to realize load stopping and play the role of overload protection. In view of the fact that the heat transfer takes a long time during the thermal bending process of the bimetallic sheet, the thermal relay cannot be used as short circuit protection, but only as overload protection.

Other ATO Relays

Thermal Overload Relays

Thermal Overload Relays

JR28 3 Phase Thermal Overload Relay

JR26 3 Phase Thermal Overload Relay

Thermal Overload Relay Function:

How to Select Thermal Overload Relay?

Thermal Overload Relay in Overload Protection

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