Tag: switchgear
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Vacuum Circuit Breakers: Features, Operation & Applications
In vacuum circuit breakers, vacuum typically at pressures ranging from 10-9 to 10-6 bar is used as the quenching medium. At such pressures, high dielectric strength can be achieved. The contact separation needed at such low pressures is only 0-20 mm and low energy mechanisms may be employed to operate the contacts through expendables bellows.…
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Switchgear Terminology & IEC Standards
Switchgear generally refers to the switching devices and their combinations, with the related control, measuring, protective and regulating equipment. The switchgear equipment basic purpose is switching and interrupting currents either under normal or abnormal operating conditions. Modern power systems, power lines and other apparatus operate at high voltages and carry large currents. When a short…
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Air-Blast Circuit Breakers: Features, Operation & Applications
Air-blast circuit breakers utilize a blast of compressed air typically at a pressure of 25–75 bar, which is directed across the path to cool and eliminate the ionized gas, in other words the air-blast is employed as the quenching medium. The air-blast cools the arc and sweeps away the arcing products to the atmosphere. This…
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Air Circuit Breakers: Features, Operation & Applications
Air Circuit Breaker Features & Operation An air circuit breaker employs atmospheric air as its interrupting medium. The arc is drawn between its contacts and extended via arc runners on to an arc chute where it is presented with a large cooling surface of arc splitter plates. These break the arc into a number of…
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Protective Relays: Function, Features & Operation
A protective relay is basically an electrical device that detects a fault in a power system and initiates the operation of the circuit breaker to isolate the defective section or component from the rest of the system. In other words, the prime function of protective relays is the timely and discriminative clearance of system faults.…
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SF6 Circuit Breakers: Features, Operation & Applications
Introduction Many modern designs of circuit breakers for use at transmission voltages utilize sulphur hexafluoride (SF6) gas both as an arc-interrupting/arc-quenching and a dielectric medium. At distribution voltages SF6 designs of circuit breakers are also used, however vacuum and bulk-oil circuit breakers still find a wide use as alternatives. The SF6 is an electron-negative gas…
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5 Causes of High-Voltage Switchgear Failures
Switchgear is basically equipment used switch ON or OFF generators, transmission lines, distributors and other equipment under both normal and abnormal conditions. Switchgear consists of switching and protecting devices such as switches, fuses, circuit breakers, relays, and so forth. In other words switchgear can be defined as equipment used for switching, controlling and protecting the…
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Switchgear Equipment
Switchgear can be defined as equipment used for controlling, regulating and switching ON and OFF power circuits. Switchgear units range from the small moulded-case unit circuit breakers in a household panel board to the huge, air break switches on 750 kV transmission lines. Switchgear equipment is generally divided into four groups, namely: Disconnect/Isolator Switches Disconnect…