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______ are used to disconnect the live system for maintenance and repairs purpose.
Insulators
Isolators
Busbars
Isolators
Isolators are mechanical switching devices used to disconnect a part of a power system from the live circuit for maintenance, inspection, or repair. They are designed to operate only under no-load or extremely light load conditions as they lack arc-quenching capabilities.
Isolators are mechanical switching devices used to disconnect a part of a power system from the live circuit for maintenance, inspection, or repair. They are designed to operate only under no-load or extremely light load conditions as they lack arc-quenching capabilities.
IbreakтАЛтЙИ0 тАФ Isolators are intended for no-load switching current conditions.
VinsтАЛтЙеVsysтАЛ тАФ Isolators must sustain system voltage across the open contact gap.
An isolator provides physical separation between the energized section and the section to be worked upon, creating a visible break in the circuit. Since it cannot break the load current, it must be operated only after the circuit breaker has successfully interrupted the power flow in the line. This ensures safety for personnel by preventing accidental re-energization during maintenance.
Isolators are also known as 'Disconnecting Switches'.
They do not have a current-breaking capacity or arc-quenching medium (unlike Circuit Breakers).
Operational sequence: First open Circuit Breaker, then open Isolator.
Must be locked or interlocked with the Circuit Breaker to prevent operation while the circuit is live.
Ensures safety by creating a visible physical gap.
Cost-effective compared to circuit breakers.
Simple mechanical construction.
Cannot be opened under full load current.
Lack of arc-quenching chambers.
Risk of damage if operated during high fault currents.
Used in transmission substations.
Used to isolate transformers, buses, and lightning arresters for maintenance.
Insulators are support materials (porcelain/glass) to provide electrical isolation from ground.
Busbars are the main junction points in a substation that collect current from multiple sources.
Isolators are strictly 'Off-load' devices.
B is correct тАФ Isolators act as a safety mechanism to provide a physical, visible gap in the circuit, allowing maintenance to be performed safely after the circuit has been de-energized by a circuit breaker.
Always remember the golden rule of switching: Isolators are operated AFTER the circuit breaker is opened, and closed BEFORE the circuit breaker is closed (the 'make-before-break' or 'sequence' rule).