Over current protection device

Abstract

An over current protection device that surely prevents a burnout by opening a power supply circuit to an electric compressor upon an over current, includes a heater which generates heat by a current flowing through the electric compressor, a first over current relay unit which is serially connected to the heater, is thermoelectrically coupled thereto, and includes a first bimetal contact piece which opens a first contact at a temperature equal to or more than a first temperature, and recovers the first contact at a temperature lower than the first temperature and higher than 0 DEG C, and a second over current relay unit which is serially connected to the heater, is thermoelectrically coupled thereto, and includes a second bimetal contact piece which opens a second contact at a temperatureequal to or higher than a second temperature higher than the first temperature, and recovers the second contact only at a temperature lower than 0 DEG C, where both the first over current relay unit and the second over current relay unit open the power supply circuit to the electric compressor.

Description

technical field [0001] The invention relates to an overcurrent protection device, which protects electric compressors used in cooling equipment such as refrigerators and small air conditioners from being affected by burning damage caused by overcurrents in their overloaded and locked states. Background technique [0002] At present, in order to protect the electric compressors used in cooling equipment such as cold storage and small air conditioners from being affected by the overcurrent state, an overcurrent protection device is provided. The bimetal which senses the temperature and operates by the heat of the heater generated by the overcurrent flowing in the motor of the electric compressor switches the switch contacts connected in series between the motor of the electric compressor and the power supply. In this case, when the operating temperature of the bimetal is reached due to an abnormal temperature of the main body casing of the electric compressor or heat generated...

AI Technical Summary

Problems solved by technology

[0014] However, since two bimetals are operated by one heater, if the type of bimetal is changed, it is difficult to manufacture a type with a different magnitude of overcurrent even if a type with a different reversing operation temperature can be produced.

That is, since the heater is one type, for example, a type that uses two bimetallic strips to perform an inversion operation at 130°C, such as the first bimetallic contact piece performs an inversion operation when an overcurrent of 10 amperes flows for 10 seconds , the type that the second bimetallic contact piece flips when an overcurrent of 20 amps flows for 10 seconds, and it is difficult to produce a bimetallic contact piece that operates at different current values

Therefore, it is difficult to produce a type with a different current value of the overcurrent flowing to the motor of the electric compressor, and there is a problem that the degree of freedom of design is limited, and it is difficult to manufacture a type suitable for the electric compressor.

In addition, because it is a method of mechanically forcibly peeling the movable contact from the fixed contact, there is also a concern that it will not be peeled off when the welding is strong.

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