Erric Ravi
RCCB or Residual Current Circuit Breaker is one of the most reliable devices to identify and trip electrical leak currents. It is a differential current detecting device used extensively in residential and industrial applications to secure low voltage circuits whenever there is a leakage fault. This device is also, at times, called a Residual Current Device or RCD. RCCB or RCD comprise a switch operator that instantly turns off in the case of current leakage. It, however, does not return to its original position through neutral. RCCB is vital in providing safety from small current leaking that may arise due to failure of insulation or by accidental human touch, which is usually not possible using only MCBs or fuses.
Do We Need RCCB When We Already Have MCBs?
To understand this question and answer it better, we should first understand the 2 most common yet hazardous electrical faults.
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A high current failure has resulted due to a low resistance fault or short current. MCBs usually protect this.
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Earth leak occurs due to several factors, including unforeseen human touch, insulation breakage of cable/appliance/socket, etc. MCBs cannot detect such low leakages, and if necessary steps are not taken, it may lead to permanent damage to appliances and even fatal accidents to human beings. RCCB comes into the picture in such cases and offers crucial electrical protection.
How Does A RCCB Function?
The core principle behind an RCCB is that incoming current to the equipment shall go back in full. RCCBs can identify the slightest difference of a few milliamperes and cut off the power supply within a fraction of a second.
Residual current is the current that leaks from a system. RCCBs are manufactured to maintain continuous monitoring of the system to study the difference between the residual current of the live wires and the neutral wires. Whenever this device detects a shift in the current number, it gets triggered to trip down the circuit. Thus, simply put, an RCCB can pick up the variation between current values in phase and neutral and disintegrate the circuit whenever there is a mismatch. Hence, the RCCB ensures reliable protection and MCB to the users of the electrical system and its connected devices.
RCCB is assembled following IS 12640 (part I): 2008 or IEC 61008-1 1996. For residential purposes, generally, the 2 pole RCCB and the 4 pole RCCB are used. The 2 pole RCCB is used for single-phase supply with only one live wire and a neutral wire. Simultaneously, the 4 pole RCCB is used for 3 phase connection with 3 phase wires and 1 neutral wire. Both these RCCBs come with a rotary switch that is used to turn the device on and off. It also has a test button that helps in conducting periodical tests to ensure its functionality.
Schneider Electric India offers the best RCCBs that are apt for domestic and industrial uses. Visit their website today to know more.
