Electrical Protection

Fuse

• Definition: A fuse is a protective device in circuit that contains a piece of wire designed to melt and break when there is a fault of overload & short Circuit.�Protection of Over load & Short Circuit�Fast Tripping Time 2ms�Automated function no indication or external contacts� Can’t reuse (other than re-wire)�Cheapest�Occupy less space�Mostly used in low voltage�Disadvantage: Difficult to find exact rating & type if required, Difficult to check status.

Isolator

�Definition: Isolator is a switching device which offers making and breaking of electric current in a circuit.��➤Switching ON/OFF, isolation�➤Used as Main switch or Main incomer�➤ Isolate portion of circuit/system/panel require Maintenance�➤No any protection�➤ Available up to 4 poles & 125A ratings.�➤Costlier than Fuse

MCB (Miniature Circuit Breaker)

• Protects from overload & short circuit conditions�Rated current not more than 125 Ampere�MCB can be reset very fast & don’t have any maintenance cost�Its interrupting current rating is under 10KA�Its trip characteristics are normally not adjustable� MCB is mainly used in domestic low voltage rating industrial Panel�Can provide status signal by adding component�Costlier than Isolator

MCCB (Molded Case Circuit Breaker)

➤Protects from overload & short circuit conditions�➤ Rated Current up to 1600A�➤ Their interrupting current ranges from around 10KA -85KA�➤ Its trip current may be fixed as well as adjustable for overload and magnetic setting.�➤ MCCB is mainly used for both low and high breaking capacity requirements mainly industrial.�➤ Provides external indication signal.�➤Costlier than MCB in price

RCCB AND RCD (Residual Current Circuit Breaker /Residual Current Device)

• Principle: RCCB works based on the principle of Kirchhoff’s current law. The law states that the incoming current must be equal to the outgoing current in a circuit.� RCCB/RCD differentiates the deviation in current values between live and neutral wires, Trips when observe leakage/drop as rated.�Provides safety and protection against earth fault as well as any leakage current� Automatically disconnects the circuit when the rated sensitivity is gone beyond� Available in 2,3,4 poles, rating from 10A-100A� Sensitivity 30, 100 300 mA� Does not provide protection against overload/short circuit� Extremely helpful to protect from shock�Costlier than MCB in Price

RCBO Residual Current breaker with Overload

• Provides safety and protection against current leakage/earth Fault, overload & short circuit.� Automatically disconnects the circuit when the rated sensitivity is gone beyond�Available in 1,2,3,4 poles, rating from 10A-100A� Sensitivity 30, 100, 300 Ma�Extremely helpful to protect from shock� Costlier in than RCCB/RCD in price

SPD (Surge protective devices )�

• Surge Protective Devices are designed to protect against transient surge conditions.
• Large single surge events, such as lightning, can reach hundreds of thousands of volts and can cause immediate or intermittent equipment failure. However, lightning and utility power anomalies only account for 20% of transient surges. The remaining 80% of surge activity is produced internally.
• Although these surges may be smaller in magnitude, they occur more frequently and with continuous exposure can degrade sensitive electronic equipment within the facility.

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Surge Protection Circuit

Phase Reversal

Interfacing DC/AC sources to control elements (Relay Protection Devices)