When do the Nuisance Trips Happen with the Earth Leakage Circuit Breakers?

Nuisance trips can take place when there is an installation with two connections to the earth. Whenever there is any high current striking near by it can cause a voltage gradient in the soil which in turn provides the ELCB with enough voltage causing it to trip.

Whenever the rod used in the installation is placed close to any earth rod of adjoining building, the leakage in the earth in the neighbouring building can also raise the ground potential and in turn cause a huge difference in voltage between the two earths. This also causes the ELCB to trip. Such occurrences do not happen often but are encountered at times which close earth rods which are unsuitable for the ELCBs are used of the installations.

Nuisance trips are at times caused even from normal and harmless currents or earth leakage happens to an extent. Nuisance trip are more often seen in the RCDs rather than in the Earth Leakage Circuit Breakers.

One of the major causes of nuisance trips is due to the accumulated currents which are caused by the installations which have a low insulation resistance. This can happen if the equipment is older or can also take place in equipments which have heating elements or can also occur in the wiring in the buildings which are longer damp as well as rainy climatic conditions. The resistance can lower in such cases due to the tracking of the moisture. If the device which is used is 30 mA and if the burden from the various sources is 10 mA then the ELCB unit would trip at 20 mA. The individual appliances in this case are safe and out of risk but such occurrences will reduce the tripping level of the unit. Such problems were majorly seen in the old installations where a single Earth Leakage Circuit Breaker was used for the protection of multiple circuits. Many of such are now replaced with the RCDs as they provide more protection to the appliances but the RCDs are more often seen to suffer in cases of false trips. 

There are also occurrences when there is a passage of fault current which is not sensed by the Earth Leakage Circuit Breaker, but the operation of the ELCB is never compromised. The ELCB just does the same by preventing the earth metal work to rise due to the dangerous voltage conditions.

Read More

Pros And Cons Of Earth Leakage Circuit Breakers

The Advantages of Earth Leakage Circuit Breakers:

·        There is one major advantage of the Earth Leakage Circuit Breakers over the RCDs. The ELCBs have not very sensitive towards the fault conditions and hence have less nuisance trips.

·        The ELCB can have a nuisance trip in situations where the voltage as well as the current in the earth line is a fault current which occurs from a live wire.

The Dis-Advantages of Earth Leakage Circuit Breakers:

·        The ELCBs do not indentify faults which do not pass current via the CPC into the earth rod.

·        A single building system cannot be split into multiple sections using the ELCBs the independent fault protection as most of the earthing systems are bonded towards a pipe work.

·        The Earth Leakage Circuit Breakers can be easily tripped by the external voltages from the things which are connected to the earthing system. For example, metal pipes, a TN-C-S combined neutral or earth.

·        The ELCBs are also much different from the RCDs as the ELCBs when connected to the leaky appliances like water heaters or washing machines or at times electric cookers can make them trip.

·        Most of the ELCBs also add some extra resistance which acts as an additional point of failure and thus affects the earthing system badly.

There are some of the Earth Leakage Circuit Breakers which do not respond towards a fault current which is rectified. There are also similar issues with the ELCBS as well as RCDs but ELCBs being much older and with some good improvements over the years, any old Earth Leakage Circuit Breaker can have little and uncommon fault current to which it might not respond to. As failures are much common with any electrical and mechanical device, the Earth Leakage Circuit Breakers which are used for them have to be properly and periodically tested to confirm that they still function properly. The Earth Leakage Circuit Breakers do not function properly if any of the earth wires get disconnected from them and they will no longer trip. Hence such installations do not function properly. 

Read More

The History and Types of Earth Leakage Circuit Breakers

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 20^th 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. 

Read More

The Working Principle of Earth Leakage Circuit Breaker

The Earth Leakage Circuit Breaker or the ELCB as it is called is a safety device which is majorly used in the electrical installations. The Earth Leakage Circuit Breakers have high earth impedance which helps to prevent shock. The ELCB helps in detecting small and minute stray voltages on the metal enclosures of the electrical equipment and it also interrupts the circuit if any dangerous or high voltage is detected. These were in wide use in the initial days till they were replaced by the residual circuit breakers as they help in detecting the current leakage directly. The main purpose of the usage of the Earth Leakage Circuit Breaker is to prevent any sudden damage to humans or any animals due to the occurrence of electric shock. 

The Operation of Earth Leakage Circuit Breakers:

Any Earth Leakage Circuit Breakers can be stated as a special type of latching relay which has the main of the buildings incoming power connected to it. This is connected through the process of switching contacts as the ELCB automatically disconnects the power which there is an earth leakage.  The Earth Leakage Circuit Breakers also help to detect any fault currents which are from the live to the ground wire and it protects within the installation. This does not take place in the case of a voltage sensing Earth Leakage Circuit Breakers. 

Read More