Category: Power Systems
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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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DC to DC Power Converters: Function, Types, Operation & Applications
DC to DC power converters also referred to as choppers provide the means to change one DC voltage to another. Normally the conversion is to a lower voltage however, we also have step-up converters. DC to DC power converters are fed from a DC supply usually comprising an uncontrolled AC to DC converter or alternatively…
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Equipment Grounding vs. System Grounding
Grounding or earthing an electrical system is the process of connecting all metalwork/frame of electrical equipment i.e. the non-current carrying part or some electrical component of the system such as the neutral point in a star-connected system, one conductor of the secondary of a transformer, and so forth to the main body of earth. An…
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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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Testing & Commissioning Protective Schemes
Generally protective equipment testing may be divided into three stages: Factory and commissioning tests confirm the performance of equipment during its development and fabrication, and its operational environment. Periodical maintenance ensures that this performance is maintained. For example, the relay manufacturer must provide sufficient testing of protective gear before it is accepted and commissioned. The…
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The Principles of Power System Protection
The Function and Principles of Power System Protection The objective of power system protection is to detect faults or abnormal operating conditions and initiate corrective action. Principles of Power System Protection There are different principles used in accomplishing power system protection, we have discussed them in the following sections: Discrimination by Time In simple radial…
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Overvoltage Protection Techniques & Equipment
Overvoltage Protection – Objective, Methods & Equipment The purpose of the protective equipment in a power system is to isolate the faulty section from the healthy system by initiating tripping for appropriate circuit breakers. This whole process must be carried out with minimum of delay and disturbance. Overvoltage, switching and other phenomena like lightning produce…
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What is Corona Discharge in Power Transmission Conductors?
Corona and its Effects in Power Transmission Systems What is Corona? Corona is the term used to describe the violet glow or ‘brush’ discharge around conductors when the air is stressed beyond the ionization point without flashover developing. When an alternating potential difference is applied across two conductors whose spacing is large as compared to…