Laplace Transform – How Time Domain Converted to Frequency Domain

In Control System, we often encounter Laplace Transform. Transfer Function is expressed as the ratio of Laplace Transform of output and input to a system. Laplace Transform is used to ease the calculation as solving differential equation is quite tiresome. Suppose there is a second order differential equation, then solving of the second order differential … Read more Laplace Transform – How Time Domain Converted to Frequency Domain

Steady State & Transient State Stability

Power System instability is basically of two forms: a) Instability of Load which means stalling of Synchronous Load connected to the system. b) Pole slipping or out of step of Generators connected to the Synchronous Grid known as Synchronous Instability. Synchronous Stability is categorized into two: 1) Steady State Stability 2) Transient State Stability Steady … Read more Steady State & Transient State Stability

Principle of Automatic Voltage Regulator

Automatic Voltage Regulator (AVR):  Automatic Voltage Regulator is a device which maintains the Generator output terminal voltage. To be more accurate, AVR is a controller which always compares the Generator output terminal voltage Vt with the set reference voltage Vrefand as per the error signal i.e. (Vref – Vt) it changes the filed excitation of … Read more Principle of Automatic Voltage Regulator

Class-A, Class-B and Class-C Tripping Classification of Generator

Generator, Generator Transformer and Unit Transformer protections have been classified into Class-A, Class-B and Class-C. Class-A tripping is further classified into Class-A1 and Class-A2. In this post we will discuss each type of tripping classes and their significance. Picture taken from http://universalerectors.com/steam_turbine_generator.html Basis of Tripping Classification: The tipping classification of Generator is based on the need … Read more Class-A, Class-B and Class-C Tripping Classification of Generator

df/dt Relay – Rate of Change of Frequency (ROCOF) Relay

Rate of Change of Frequency (ROCOF or df/dt) relay is used for fast load shedding, to speed up operation time in over- and under-frequency situations and to detect loss of grid. For better understanding of role and operation of df/dt relay, let us first study the variation of frequency with load for a Grid. Graphical … Read more df/dt Relay – Rate of Change of Frequency (ROCOF) Relay

Transformer Oil Filling- Why Vacuuming Required?

The oil can only be filled in the transformer which satisfies the standard specifications mentioned by the manufacturer of transformer. Normally Transformer is supplied with gas filled i.e. the Main Tank of Transformer is filled with Nitrogen gas under some specified pressure to prevent any degradation of the insulation of core and winding. But we … Read more Transformer Oil Filling- Why Vacuuming Required?

Variable Frequency Transformer (VFT) – Construction and Working Principle

Variable Frequency Transformer or simply VFT is quite a new technology to connect two asynchronous Grids. Asynchronous Grids mean two power systems operating at two different frequencies. The world’s first VFT was installed and commissioned in the year of 2004 at Hydro- Quebec’s Langlois substation, where it is used to exchange up to 100 MW … Read more Variable Frequency Transformer (VFT) – Construction and Working Principle

Why is it Important to Maintain a Constant Frequency in a Power System?

Frequency all over a synchronous Power Grid is the same in steady state. Mind the word Synchronous Power Grid, as there may be two different grids operating at slight different frequencies. It is very important to maintaining a constant frequency or to frequency to vary over a very narrow band in a power system operation. … Read more Why is it Important to Maintain a Constant Frequency in a Power System?

Impulse Voltage Tests of Circuit Breaker and Standard Impulse Waves

This test is necessary for all indoor and outdoor breakers. The test is carried out as follows: Standard impulse wave of specified amplitude is applied five times in succession. If flash-over or puncture of insulators does not occur, the circuit-breaker is considered to have passed the test. If puncture occurs or if on two or … Read more Impulse Voltage Tests of Circuit Breaker and Standard Impulse Waves

What is Endurance Test of Circuit Breaker?

Endurance Test of Circuit Breaker is conducted to check the healthiness of its mechanical parts i.e. operating mechanism. In this test, Circuit Breaker is operated several times and checked for any damage of its mechanical parts / contacts. The breaker should be in a position to open and close satisfactorily. This test is also called … Read more What is Endurance Test of Circuit Breaker?