Once widely used, recent installations have changed to using residual current devices (RCD, RCCB or GFCI), which directly detect leakage current.
what is the purpose of elcb?
ELCB is generally used in industrial and housing electrical systems and is often used in places where the leakage is serious, such as bathrooms, swimming pools, etc.
The main purpose of an Earth Leakage Circuit Breaker (ELCB) is to prevent human or animal injury from electric shock and fire caused by a short circuit, by automatically disconnecting the circuit when a current leakage is detected. All in all, ELCB plays an important role in electrical system safety.
ELCBs protect equipment by detecting fault currents from the live wire to the ground wire. An induction coil in an ELCB device senses a sufficiently high voltage in the circuit, and it disconnects the device and remains off until manually reset.
What types of ELCB are available?
There are two types of ELCB
- Voltage operated (Voltage ELCB).
- Current operated (Current ELCBor RCD, RCCB).
Voltage Earth Leakage Circuit Breaker
Voltage ELCB is a voltage operated circuit breaker, it has been widely used, many are still operating, but are no longer installed in new buildings.
The voltage ELCB contains a relay coil, one end of the coil is connected to the metal body and the other end is grounded.
The voltage operated ELCB detects the potential rise between the protected interconnected metal products (equipment frame, conduit, enclosure) and the remotely isolated ground reference electrode.
They operate at a detected voltage of approximately 50 volts to open the main circuit breaker and isolate the power supply from the protected area.
If the voltage of the device body rises due to the insulation failure of the device or contact with metal parts, the difference between the ground voltage and the body load voltage may result, and the risk of electric shock may occur.
Compared with current ELCBs, voltage ELCBs have several disadvantages as below:
- A broken wire in the fault to the load part or the ground part will cause the ELCB to fail to operate.
- An additional third wire from the load to the ELCB is required.
- Separate equipment cannot be grounded separately.
- Any additional connection to the earth on the protected system may disable the detector.
- ELCB can sense equipment failure and cannot detect whether a humans accidentally touched the live part of ELCB.