Description

• RCCB (residual current circuit breakers) are also named as ELCB (earth leakage circuit breaker).
• This is a safety device used in electrical installations with high Earth impedance to prevent shock.
• It detects small stray voltages on the metal enclosures of electrical equipment, and interrupts the circuit if a dangerous voltage is detected.
• This is a specialised type of latching relay that has a buildings incoming mains power connected through its switching contacts so that it disconnects the power when earth leakage is detected.
• These breakers typically consists of a current transformer, which has multiple primary windings and one secondary winding.
• Neutral and line (or lines in multiple phase systems) wires act as the primary windings.
• A wire wound coil is the secondary winding.
• The current through the secondary winding is zero at the balanced condition.
• In balance condition, the flux due to the current through the phase wire will be neutralized by the current through the neutral wire, since the current, which flows from the phase will be returned to the neutral.
• When a fault occurs, a small current will flow to the ground also.
• This makes an unbalance between line and neutral current and that creates an unbalanced magnetic field.
• This induces a current through the secondary winding, which is connected to the sensing circuit.
• This will sense the leakage and send signal to tripping system.