What is Residual Current Circuit Breaker: Functions and Working Principle?

In today’s society, which operates with numerous electrical appliances, it is crucial to understand how the electrical components work. The varying effects caused by electrical faults like short circuits or current leaks can cause dangerous effects like electric shock or fire outbreaks. To minimize such risks, several protective devices are provided in electrical systems. Among such devices, the most important is the Residual Current Circuit Breaker (RCCB). This article aims to explain what RCCB is, its purpose, how it functions, and why it is an indispensable item in the modern world of electrical systems.

What is RCCB? 

RCCB, or Residual Current Circuit Breaker, is a device intended to protect against leakage currents in a given circuit. It switches off the supply voltage each time it sees a difference between the connected live (hot) and neutral wires. This imbalance clearly shows a current leak that may be dangerous to humans and appliances, implying a current leakage.

RCCB is an important safety item that excludes electrical failure incidents due to leakage. Such leakages may occur if a person touches the live wire or due to an appliance malfunction. RCCB immediately interrupts the electrical supply once it detects a leakage, thus protecting people and equipment.

Function of Residual Current Circuit Breaker  

A residual current circuit breaker performs the duties of a circuit breaker by detecting leakage currents that the other circuits may not detect. Normal circuit breakers can only be tripped by overcurrent or short circuits. However, RCCBs can trip by any residual current, meaning that if there is a leak, the RCCBs will detect it. The main functions of a Residual Current Circuit Breaker are as follows:

• Protection from Electric Shock: The main role of RCCBs is to protect people from electric shocks due to the earth's faults. For instance, if someone accidentally touches a live wire, the RCCB can measure the leakage current and break the circuit before much damage occurs.

• Fire Prevention: Steady direct leakage current can result in overheating of electrical equipment or wiring and, therefore, cause fires. Since they can sense these leakage currents and break the circuit, they are useful in preventing electrical fires.

• Fault Detection: The function of RCCB includes identifying faults in the wiring and appliances. A current in the system is a sign of a problem that must be corrected to avoid further system loss.

• Electrical Isolation: RCCBs also operate as switching devices that disconnect the power supply to the circuit at fault until it becomes safe to supply again.

Residual Current Circuit Breaker Working Principle  

RCCBs work based on current variation from the ‘live’ phase to the neutral phase. In a healthy circuit, the current that enters via the conductor should be equal to the current that leaves via the return or neutral lines.

However, when some problem arises, like a leakage current because a person has touched the live wire or insulation failure, this stability is disturbed. The working of the residual current circuit breaker relies on the imbalance mentioned above.

An RCCB uses a core balance transformer and includes a primary and secondary winding. The live and the neutral conductors go through the primary winding while inducing magnetic fields, which are proportional to the currents within the conductors. Normally, these magnetic fields are opposites of each other, meaning that when the first field engulfs a point, the second has its magnetic field pointing in the opposite direction; hence, in actual sense, there is no net magnetic field in the transformer core.

Leakage current: Whenever there is a leakage current, an unbalanced field in the core occurs, causing a residual mass current, which in turn sets up a voltage in the secondary winding. This induced voltage causes a trip circuit, which halts the circulation of the current, which offers further damage.

The general working of the residual current circuit breaker is extremely effective, making it possible for RCCBs to identify leakage currents as low as 30mA. This level can trigger a potentially fatal electric shock.

Purpose of RCCB  

RCCB has the purpose of safeguarding human life from electrocution that may be fatal. However, it would be hard to overemphasize its ability to protect appliances and the entire electrical system from damage. Some of the key purposes of RCCBs include:

• Human Protection: RCCBs protect people from electrical shocks because they can switch off against leakage currents.

• System Safety: They meet the requirements of a safe system by detecting unauthorized circuits and avoiding hot circuitry and possible fire.

• Compliance with Electrical Standards: This device is typically required by law in most countries when installing electrical bridges in homes and businesses.

Why RCCBs are Important in Electrical Installations?  

RCCBs are crucial in electrical installations due to the following reasons:

• Enhanced Safety: RCCBs work hand in hand with circuit breakers, offering extra protection that the latter does not offer. A normal circuit breaker will safeguard against overload and short circuits; it might not see leakage currents, which can be lethal in small amounts. This is where RCCBs have strategic importance.

• Mandatory Requirement: Traditional electrical safety codes demand RCCBs in homes and businesses worldwide. This is because there has been evidence of their efficiency in preventing mishaps that arise from electrical failure.

• Cost-Effective Protection: An RCCB will save consumers more money in the long run since replacing damaged equipment with electric currents and fires will be significantly higher than the cost of a good quality RCCB. Consequently, the residual current circuit breaker price is a small price the user will pay to protect a circuit.

Also Read - MCB vs RCCB: Which is Best for Your Home Appliances?

Conclusion  

It is very important to understand what RCCB is and how it contributes to the electrical safety in your house or workplace. RCCBs are intended to sense small residual currents due to electrical outrage and isolate the electric supply to prevent electric shock, fire outbreak, or damage to electrical appliances. One of the primary functions of residual current circuit breakers is to protect that normal circuit breakers cannot provide. As such, it plays a crucial role in protecting any complicated electrical installation today.