RCCB (Residual Current Circuit Breaker)
RCCB are important safety measures for protecting electrical circuits. This current-sensing device automatically disconnects a circuit when a fault occurs, or the current exceeds its sensitivity.
Designed to protect an individual from shocks, electrocutions, and fires, an RCCB is especially helpful in cases of earth faults that occur suddenly. As a result, an RCCB ensures that an electric shock will not occur in such cases since it trips the circuit immediately.
Principle behind RCCB
As stated by Kirchhoff’s law, RCCBs work by matching the incoming current with the outgoing current in a circuit. This allows an RCCB to compare live and neutral wire current values. The live and neutral wires should have the same current flowing to the circuit. If a fault occurs, the residual current is the differential between the neutral wire current and the fault current.
RCCBs also have a test button that allows users to test their functionality by creating a small leakage current. By pressing the test button, the live wire on the load side is connected to the supply neutral, bypassing the neutral coil of the RCCB. This causes an imbalance in currents and fluxes, which should trip the RCCB. This means the RCCB must be replaced or repaired if it does not function correctly.
Advantages and Disadvantages of Residual Current Circuit Breakers
Some of the advantages of using RCCBs are:
- Simple test and reset buttons make them easy to install and use.
- This device provides protection against earth faults as well as leakage currents.
- It disconnects the circuit automatically when its sensitivity exceeds its rating.
- Suitable for both cable and busbar connections with dual terminations.
- In addition to protecting against voltage fluctuation, it includes a transient voltage filter.
Some of the disadvantages of using RCCBs are:
- In the absence of standard waveforms, the RCCB will not function. The main reason is that RCCBs are designed to operate with normal supply waveforms.
- RCCB might trip unintentionally. Due to sudden changes in electrical load, especially in old appliances, a small current can flow to the earth when there is a sudden change in electrical load.
- RCCBs do not protect against current overload. It covers only when the live and neutral currents are different. Despite this, detecting an excess of current is impossible.
- The RCCB does not protect against shocks caused by line neutrality. This is mainly due to the balanced current in them. By holding both terminals together, the current is balanced.
- The RCCB does not protect from overheating caused by improperly screwed conductors.
