Answer Posted / shahid parvez
ELCB stands for “Earth Leakage Circuit Breaker” and it is used for protecting a person from electric shock and injury. The needs of these devices arise because of the number increasing in injuries as well as deaths because of electric shock. This device is invented almost 50 years ago, but nowadays ELCB is not suitable because of its some disadvantages hence another device RCB (Residual circuit breaker) or RCD (Residual Current Devices) whose functionality is same with more advantages, but theory of operation is entirely different from ELCB.
Residual Current Breaker (RCB) works on the assumption that the current going to the electronics device must come out from the neutral wire, if there is no other way for current flow. In simple words, RCB measures the current going inside the connected device and coming out from the device. If both of these current are equal, then there would no problem with the normal functionality of the device.
This device is also known as Current Operated ELCB.
This device is more sensitive and accurate than ELCB and its functionality does not (entirely) depend on the earthed rode wire connection like voltage ELCB.• ELCB is the old name and often refers to voltage operated devices that are no longer available and it is advised you replace them if you find one.
• RCCB or RCD is the new name that specifies current operated (hence the new name to distinguish from voltage operated).
• The new RCCB is best because it will detect any earth fault. The voltage type only detects earth faults that flow back through the main earth wire so this is why they stopped being used.
• The easy way to tell an old voltage operated trip is to look for the main earth wire connected through it.
• RCCB will only have the line and neutral connections.
• ELCB is working based on Earth leakage current. But RCCB is not having sensing or connectivity of Earth, because fundamentally Phase current is equal to the neutral current in single phase. That’s why RCCB can trip when the both currents are deferent and it withstand up to both the currents are same. Both the neutral and phase currents are different that means current is flowing through the Earth.
• Finally both are working for same, but the thing is connectivity is difference.
• RCD does not necessarily require an earth connection itself (it monitors only the live and neutral).In addition it detects current flows to earth even in equipment without an earth of its own.
• This means that an RCD will continue to give shock protection in equipment that has a faulty earth. It is these properties that have made the RCD more popular than its rivals. For example, earth-leakage circuit breakers (ELCBs) were widely used about ten years ago. These devices measured the voltage on the earth conductor; if this voltage was not zero this indicated a current leakage to earth. The problem is that ELCBs need a sound earth connection, as does the equipment it protects. As a result, the use of ELCBs is no longer recommended.
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