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ELCB versus RCCB - ELCB vs RCCB

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ELCB versus RCCB - ELCB vs RCCB

Bài gửi  duyminh on Mon Apr 05, 2010 9:48 am











And ELCB is an Earth Leakage Circuit Breaker which is the same as an RCCB - a Residual Current Circuit Breaker, also sometimes referred to as an RCD - Residual Current Device.

You also get RCBOs - Residual Current circuit Breaker with Overcurrent protection, which combine the RCCB and MCB functions into one package.

If your RCCB/ELCB has tripped, there are but two possibilities : 1) It tripped on an earth leakage current, or more precisely on an imbalance between the currents in phase and neutral conductors, or 2) The device is faulty.

Be aware that the tripping current can be quite small. Here in New Zealand the RCDs are 30mA devices which means that a leakage current of as little as 20mA will often cause a trip, in other countries the limit is different and may be as little as 5mA. Also, the leakage current does not need to be present for long before the RCD will trip - 10 mS or less is not uncommon.

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If ELCB is taken to mean Earth Leakage Core Balance it means Residual Current Device. Earth Leakage Circuit Breakers can use other technologies beside Core Balance / Residual Current for a detection regime, which is why the RCD and RCCB names have superceded ELCB.

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ELCB
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RCD
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This depends on the design. If your unit has a seperate torroid centralising the conductors can be quite critical, perspex with holes drilled for each conductor is ideal for this application.

In the case of Miniature Circuit Breaker Cases with either RCD or RCDMCB and therefore the torroid built into the case, the conductors should be well centered. Problems can arise from a few items, capacitive leakage on start up of devices such as television sets, poorly constructed units and EMI. There are pirate items out there which look like major brands, especially Group Schnieder brands (Merlin Gerin, Telemecanique, Clipsal, Square D, PDL, Wilco, Ring Grip and others). Schneider have taken action and Ebay seems to have removed them from their listings. If you are suspicious contact your manufacturer's rep.

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An earth leakage circuit breaker (ELCB) is a device with two earth terminals used to directly detect currents leaking to earth from an installation and cut the power. They were mainly used on TT earthing systems before RCDs became common. They have been almost totally replaced by RCDs (except in very old installations) due to a number of problems. ELCB is connected to the grpunding wire, and it measures the current going through grpudn wire. If that current is too high, then it cuts the power feed. ELCB cannot detect earth faults that do not go through the earthing system and usually they introduce additional resistance and an additional point of failure into the earthing system.


A residual current device (RCD), or residual current circuit breaker (RCCB), is an electrical wiring device that disconnects a circuit whenever it detects that the flow of current is not balanced between the phase ("hot") conductor and the neutral conductor. The presumption is that such an imbalance may represent current leakage through the safety ground wiring or through the body of a person who is grounded and accidentally touching the energized part of the circuit.

RCDs/RCCBs operate by measuring the current balance between two conductors using a differential current transformer, and opening the device's contacts if there is a balance fault (i.e. a difference in current between the phase conductor and the neutral conductor). More generally (single phase, three phase, etc.) RCDs operate by detecting a nonzero sum of currents, i.e. the current in the "hot" or "hots" plus that in the "neutral" must equal zero (within some small tolerance), otherwise there is a leakage of current to somewhere else (to ground, or to another circuit, etc.). In the United States and Canada, a residual current device is also known as a Ground Fault Circuit Interrupter (GFCI) or an Appliance Leakage Current Interrupter (ALCI). In Germany, one is known as a FI-Schalter.

German law, for example, requires the installation of RCDs for circuits leading to bathrooms (due to the highly increased danger of leakage currents when operating electrical devices in a wet environment; a hair dryer falling into a bathtub might otherwise be fatal). In Finland the RCDs should be installed at least to bathroom circuits and to the circuits that are outside the house and similar potentially dangerous locations etc..

U.S. law (the National Electrical Code) requires GFCIs in bathrooms, kitchens, garages, exterior areas, crawl spaces, unfinished basements, near wet bars, swimming pools, and spas.

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RCCB & ELCB khác nhau hay giống nhau?

RCCB: Residual Current Circuit Breaker
ELCB: Earth Leakage Circuit Breaker
Residual có nghĩa là dư ra, nguyên nhân - không cụ thể
Earth Leakage: rò ra đất - nguyên nhân cụ thể hơn
Tuy nhiên, nếu nhìn trên góc độ mạch điện và các nguyên tắc bảo vệ thì rõ ràng RCCB và ELCB hoàn toàn giống nhau, chỉ khác nhau về tên gọi mà thôi. Tuy nhiên, đúng nhất chính là cấu tạo và phương pháp sử dụng của ELCB và RCCB là giống nhau hoàn toàn. Ngoài ra còn có một loại nữa là RCD, RCD - Residual Current Device là một thiết bị luôn gắn kèm với MCCB hay MCB. RCD có một cần liên kết với MCB để khi xảy ra hiện tượng dư dòng điện sẽ cắt MCB để cắt mạch điện. Một loại khác nữa có tác dụng vừa chống dòng rò, vừa bảo vệ quá tải được gọi tên là RCCBo (tên gọi theo ABB).

RCBO:Residual Current Circuit Breaker with Overcurrent Protection:là một thiết bị được tích hợp RCCB: (bảo vệ dòng rò/không cắt được quá dòng) + một cái MCB (bảo vệ ngắn mạch, quá dòng/ko cắt được dòng rò) => RCBO:vừa cắt dòng rò vừa cắt ngắn mạch/quá tải.








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