The Earth Leakage Circuit Breakers were initially used on the TT
earthing systems, but now these are replaced by the residual current devices.
There are few systems which still use the Earth Leakage Circuit Breakers.
The ELCBs which were used
earlier help in detecting the sine wave currents but were not useful for the
rectified fault current. As time passed by, the filtering capacity over the
nuisance trips has also seen some improvement. These Earth Leakage Circuit
Breakers used to offer very little safety and also the risk of a nuisance trip
was always high. Some of the major companies which manufacture the Earth
Leakage Circuit Breakers are Major Tech, Fuji Electric, Schneider Electric,
Legrand, Havells, ABB, Siemens AG, Areva T&D, Camsco, Telemecanique, Orion
Italia, Crabtree, MEM, and Terasaki.
The
Types of Earth Leakage Circuit Breakers:
There are majorly two types of
ELCBs. They are the voltage operated and the current operated.
The voltage operated ELCB s
were first seen and invented in the 20th century and they also
provided a major advancement in terms of safety. These were very useful for
mains electrical supplies which had inadequate earth impedance. Though there
are many voltage operated ELCBs, there are not many new installations. A
voltage operated ELCB helps to detect a sudden rise in the potential in between
the metal work (which is mostly inter connected) and an isolated electrode.
Most of these operate at a potential which is detected at 50 volts.
The voltage operated ELCBs also
have a second terminal which is used for the connection of the remote reference
earth connection.
The current operated ones are
the Residual-current devices or the RCDs which have majorly replaced the
voltage operated Earth Leakage Circuit
Breakers. They gained popularity as they help in protection of the earth
leakage using a different methodology of detection.
Whenever the term Earth Leakage
Circuit Breakers is used, it means the usage of the voltage operated ELCB.
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