Line Loadability – Universal Line Loadability Curve

Loadability of line is defined as the extent of load which can flow through the line without exceeding the limitations. Line Loadability is expressed in percentage of Surge Impedance Loading of line. The limiting factor for line loading are: thermal limit, voltage drop limit and steady state stability. The loading of line shall not exceed … Read more

Grounding / Earthing Transformer

Grounding Transformer is often called Earthing Transformer. The purpose of Grounding Transformer is to artificially create neutral point. In Delta Connected Transformer or Generator where neutral point is unavailable or in case where neutral point is inaccessible, Grounding Transformer is used to create neutral point. Constructional Design of Grounding Transformer Grounding Transformer is so designed to … Read more

Why Primary Current Injection Test Required?

Many times I have been asked to justify why to conduct primary current injection test at rated current of circuit? Why to invest money in purchasing Primary Current Injection Kit? This is why I decided to write a topic on the importance of primary current injection test. After reading the topic you will be able … Read more

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

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 Basis of Tripping Classification: The tipping classification of Generator is based on the need … Read more

Low Forward Power Protection of Generator

Low Forward Power means the output of Generator is sufficiently reduced. Low Forward Power Protection is basically a check not a protection i.e. Generator is tripped after having a check that its forward power has reduced. When the machine is generating and the CB connecting the generator to the system is tripped, the electrical load … Read more

Reverse Power Protection of Generator

A synchronous Generator / Alternator is expected to supply active power to the system in normal operating condition. If the turbine i.e. prime mover fails the Generator / Alternator connected to the system will continue to operate as synchronous Motor drawing active power from the system. This reversal of power flow due to loss of … Read more

Dead Machine Protection of Generator

Dead Machine Protection in a Generator is provided to ensure that Generator is not energized accidentally in standstill condition or when the Generator is on Turning Gear. Accidental energization of Generator when the machine is not running can cause severe damage to the machine. (How? You will be able to answer after you go through … Read more

Pick-up Current, Plug Setting Multiplier (PSM) and Time Setting Multiplier (TSM)

Plug Setting Multiplier and Time Setting Multiplier are used only for Electromechanical Relays. These terms or parameters are not so used in Numerical Relays but they are conceptually used and incorporated in Numerical Relays too but the way of their implementation is quite different than that of Electromechanical Relays. In this post we will focus … Read more

Transformer Physical Protections

Transformer Physical Protection refers to the Protections which used the physical quantities to protect the Transformer. Apart from electrical protections which uses the electrical quantities to judge a fault and based upon the judgment, the electrical protections of Transformer isolates the Transformer. On contrary, physical protections continuously measure the physical quantities like oil / winding … Read more