Low-voltage Circuit BreakersEarth Leakage Circuit Breakers

Structure of an Earth Leakage Circuit Breaker

Our earth leakage circuit breaker is generally composed of a ZCT (Zero-phase-sequence Current Transformer) + Earth leakage relay + Circuit breaker.
The ZCT detects earth leakage current, notifies the electronic circuit, and shuts off the circuit using an internal tripping device.

Necessity of Earth Leakage Circuit Breakers

Dangers of earth leakage

A person feels tingling when a current of less than 5 mA is applied to the human body, however this range does not produce life-threatening effects. When a current of between 5 mA and 20 mA is applied, the motor nerves are paralyzed and the person becomes unable to move. If this condition continues, it puts the person in danger. When a current of between 20 mA and 100 mA is applied, irregularities in heart function occur, and it endangers the person’s life. A leakage current of 100 mA or more can cause a fire.
An earth leakage circuit breaker detects earth leakage of approximately 15 to 30 mA, and immediately shuts off the circuit within 0.1 seconds, preventing an accident.

Dangers of earth leakage

In order to prevent accidents caused by earth leakage, laws and regulations prescribe the locations where earth leakage breakers must be installed.
As shown in the figure below, in cases such as when an electrical device is used in a location where there is humidity or moisture, or when a portable motor-driven appliance is used in a location of high conductivity such as an iron plate or iron frame, an earth leakage circuit breaker is necessary.