What is the function of an overload protector in an industrial chiller?
2021-03-15
Industrial chillers sometimes shut down due to excessive cooling loads, a precaution taken to ensure the safe operation of the unit. At the heart of this protection system is the overload protector, which plays a critical role in preventing damage. Below, we’ll introduce industry professionals to the operating principles and proper usage of the overload protector. When running the chiller, it’s advisable to remain vigilant and take appropriate care to avoid unnecessary damage and potential equipment losses.
The overload protector is a circuit protection device designed to meet the practical needs of the electrical control industry. It incorporates microcontroller technology, offering comprehensive functionality, reliable operation, strong anti-interference capabilities, and robust performance in harsh working environments. This device provides effective protection for power systems and wound-rotor motors against overcurrent, short circuits, phase loss, phase imbalance, phase reversal, and during the motor startup process—specifically by automatically bypassing the high inrush current typically associated with motor start-up.
The components of an overload protection device for chillers: General refrigeration compressors used within the cooling system typically feature a bimetallic, snap-action overload protector. This protector consists of a heating element, a bimetallic strip, and two stationary contacts, forming a complete circuit that is connected in series with the compressor’s power supply.
The working principle of the refrigeration overload protection device is that, when the current in the system circuit increases unexpectedly, the heated wire generates significant heat. This causes the bimetallic strip to bend upward under the thermal influence of the heating element, ultimately triggering the circuit breaker and cutting off the entire power supply.
When the compressor casing or motor temperature becomes excessively high—even if the operating current remains normal—no thermal wire will activate. Similarly, even with very low current flowing through the circuit, the same phenomenon can occur if the water-cooled compressor’s housing or motor has already reached an unsafe overheating level. This feature effectively safeguards the safe operation of the refrigeration compressor. Conveniently, this protective mechanism is automatically resettable, making it highly user-friendly during operation.
Cooling unit overload protection device: The bimetallic strip also deforms, bending upward and disengaging from the two stationary contacts, thereby breaking the circuit. This protector features automatic reset functionality and provides dual protection against overcurrent and overheating—commonly used for installation between the driving and driven sides of a power transmission system. When an overload fault occurs (torque exceeds the set value), the torque limiter triggers a separation, effectively safeguarding both the transmission mechanism and the connected load.
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