Earthing System

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 will discuss the electrical faults that normally occur in a power system. A short-circuit fault means the connection between two conductive parts of the system through a low-impedance path, where these two parts are at different voltage levels. Due to the low impedance of the path, as well as the voltage … Read more

The primary objective of a power system protection scheme is to isolate only the faulty section of the network while keeping the healthy portions in service. This approach improves system reliability and ensures continuity of power supply to consumers. Whenever a fault occurs in any part of a power system, it is desirable to disconnect … Read more

The tiny cylindrical resistors used in electronic circuits use color banding to show their resistance value. Manufacturers use four such color bands on the resistor body. Each band indicates a specific value. Not only the color of the band, but also the sequence or positions of the bands determines the overall resistance value of the … Read more

A power substation requires the earthing system for three main purposes. The purpose of earthing is to keep any voltage on metal frameworks below dangerous levels during normal or fault conditions. In directly earthed neutral system, it is not always possible to keep metal parts exactly at true earth potential when fault current flows. Therefore, … Read more

Scientists have proposed various theories to explain how electric charges form and separate inside clouds. In reality, charge formation and separation inside clouds are very complex natural phenomena. Engineers mainly need to know that charge separation occurs in thunderstorm clouds. In general, the negative charge concentrates in the main lower part of a thundercloud. In … Read more

Eriksson Striking Distance Equation The earlier equation, which relates striking distance to return stroke current, does not imply everything. Because the earlier lightning models assumed that the striking distance depends only on the return stroke current. However, Eriksson found this was not a fully correct prediction. He showed that the height of the structure also … Read more

Empirical design methods protect substations and transmission lines from lightning using practical experience. The two methods are fixed angles and empirical curves. Both give acceptable protection. Fixed Angle Method of DSLP Here, we assume that a lightning mast or shielding wire protects an area below it within a fixed angle. It saves all equipment inside … Read more