Tricky but Easy Electrical Engineering!
Zoning in Power system Protection is an important philosophy and must be done carefully so that no part of the system remains unprotected in any condition. To limit the extent of the power system that is disconnected when a fault occurs, protection is arranged in zones. The principle is shown in figure below. … Read more
According IEC, Knee Point Voltage of a Current Transformer is defined as the voltage at which 10 % increase in voltage of CT secondary results in 50 % increase in secondary current. If you carefully read the definition, you will notice that it is something related to saturation of Current Transformer CT. Never mind, I will … Read more
In Switchyard different Bus Bar arrangements are used for evacuation of power generated but the two most used schemes are One and Half Breaker Bus System and Double Bus Bar arrangement. In high voltage Switchyard like in 400 kV Switchyard, One and Half Breaker Bus System is used due to many advantages of this scheme. … Read more
An Earth Leakage Circuit Breaker (ELCB) is a safety device used to directly detect the leakage current to the Earth from an installation and cut the power supply. Basically ELCB is used where the earth impedance is high. Because of high earth impedance, the voltage difference between the Metallic part of the Installation and Earth … Read more
What is Circuit Breaker? Circuit Breaker is switch capable of making or breaking the circuit under no-load as well as on-load condition. It can make or break circuit either manually or by remote control. A Circuit Breaker in conjunction with Relay can break the circuit under fault condition. You may also like to read, Basic Principle … Read more
Most of us are aware of Electromagnetic Relays and Static Relays but most us may not be well acquainted with Numerical Relay. If I define a Numerical Relay, honestly speaking it will seem to be quite tough but in reality they are very user friendly and easy to implement different types of protection scheme. However … Read more
Relay is a switch which senses fault in a system and once fault is sensed by the Relay, it issues trip command to the Circuit Breaker, CB to isolate the faulty section of the network from the healthy section. The Relay detects the abnormal condition by continuously monitoring electrical quantities which are different for healthy … Read more
In earlier posts we discussed, Concept of Symmetrical Components and Calculation of Symmetrical Components. It is recommended to go through these topics before analyzing Single Line to Ground Fault. You must read, Concept of Symmetrical Components and Calculation of Symmetrical Components Let us consider a three phase system with earthed neutral as shown below. Let us … Read more
Electrical Faults can be classified into two categories: Shunt Faults and Series Faults. Shunt faults include power conductor or conductors to ground or short circuit between the conductors. Series type of fault is basically unbalance in system. Suppose we have used Fuse / Breaker to protect the circuit. If one or two phases open while … Read more
We are now aware of the concept of Sequence components of current / voltage. If you have miss this concept, please read Concept of Symmetrical Components. Now we are at a stage to calculate the zero, positive and negative sequence components of current / voltage. As already discussed any three phase unbalanced voltage / current can … Read more