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We know that a circuit breaker has two operational positions-open and close. During the closing operation, the circuit-breaker contacts close against few opposing forces. We shall discuss those forces in details here. It is very important to know these forces. Again, during the opening operation, the closed contacts travel back as fast as possible. The … Read more
In this article, we shall discuss the earth fault protection of a balanced three-phase network. Balanced Three-Phase Network Suppose this is a balanced three-phase network. Also, assume this is the representation of a three-phase star-connected winding of a power transformer. Although we can represent all balanced three-phase networks in the same manner, in our case … Read more
In this article, we are going to discuss the conventional sources of electrical energy. There are mainly three types of conventional sources of electrical energy: Thermal Power Plant In a thermal power plant, coal is first pulverized into a fine powder to increase its calorific value and improve combustion efficiency. Coal is the main fuel … Read more
A positive charge attracts a negative charge. Also, a negative charge attracts a positive charge. It is needless to say the force of attraction depends upon the quantity of charges. Also, it depends on the distance between the charges. Similarly, similar charges repel each other. That means a positive charge repulses another positive charge. Similarly, … Read more
A capacitor is a system where two conducting plates remain face to face with a dielectric medium in between them. When we connect the capacitor across a voltage source, opposite charges accumulate on the two opposite plates. Obviously, the charge of one plate is positive with respect to the charge of the other plate. We … Read more
A fault implies an abnormal condition in the electrical power system. Only the failure of insulation causes a fault. A fault causes an excess current to flow through an unintended path. Low insulation reduces system impedance. When the system impedance falls below the lowest load impedance a fault generates. A power system network consists of … Read more
An E2-class circuit breaker is just a normal circuit breaker. However, it has a special design criterion to perform maintenance-free operations for interrupting fault currents. An E2 class circuit breaker is expected to interrupt fault currents for a prolonged period of 25 years without requiring any intermediate major maintenance of its interrupting mechanism. This E2 … Read more
We usually assume that the conductors are suspended in free space. This assumption makes the mathematical derivation simple. However, in real-world overhead transmission, conductors are strung above the earth. Therefore, the earth influences the electric field around the conductors. Consequently, it slightly changes the capacitance of the line. To account for this effect without making … Read more
In this article, we discuss the voltage ratio test for a three-phase power transformer. The voltage ratio test of a three-phase transformer is quite simple. We use a TTR meter, which means Transformer Turns Ratio Meter or Transformer Turns Ratio Measuring Instrument. This instrument commonly has six probes: three for the high-voltage terminals and three for … Read more
In this article, we shall discuss the design, assembly, and testing details of an indoor switchgear with a vacuum circuit breaker. Most commonly, we apply these switchgears for 11 KV systems and sometimes for 33KV systems. The manufacturers generally manufacture modern indoor switchgears for 1250A to 800A normal current rating with 25 KA as its … Read more