Tricky but Easy Electrical Engineering!
Before going into the calculation part of Stabilizing Resistor, I will first explain the purpose of Stabilizing Resistor in High Impedance Differential Protection. Stabilizing Resistor in High Impedance Differential Protection is used to prevent the operation of Relay in case of through fault. Through fault is a fault outside the zone of protection. Lets us … Read more
The concept of Subtransient, Transient and Steady State arises in case of fault in an Alternator. Let us assume a sudden short circuit in three phase of alternator. The fault current will flow in all the three phases of alternator and its waveform will be as shown in figure below. When the alternator is short-circuited, … Read more
We have already discussed about staring methods of Single Phase Induction Motor. If you miss that please read here, 1) Revolving Field Theory of Single Phase Induction Motors 2) Starting Methods of Single Phase Induction Motors The schematic diagram of Capacitor Split Phase Motor is shown in figure below. Like in resistor split phase motor, … Read more
As discussed in earlier post Revolving Field Theory of Single Phase Induction Motors, a single phase induction motor with main stator winding alone has no inherent starting torque as the main stator winding only produces stationary pulsating air gap flux wave. For the development of starting torque, rotating field at the starting must be produced. There … Read more
Revolving Field Theory is used for the analysis of behavior of Single Phase Induction Motor. Before going into the details of Revolving Field Theory, first we should know why do we need to study this theory? Well, a Single Phase Induction Motor with its main winding alone can be represented as shown in figure below. … Read more
Direct-on-Line or DOL Starting is the simplest mode of starting of Induction Motor where the stator is directly connected to the mains supply as shown in figure below. The motor starts with its own characteristics. When it is switched on, the motor behaves like a transformer with its secondary, formed by the very low … Read more
We know that 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 … Read more
The protection provided by the protective relaying equipment can be categorized into two types as: a) Primary protection b) Back-up protection The primary protection is the first line of defense and is responsible to protect all the power system elements from all the types of faults. The backup protection comes into play only when the primary protection … Read more
Coulomb’s law is an experimental law formulated in 1785 by the French colonel, Charles Augustin de Coulomb. It deals with the force a point charge exerts on another point charge. By a point charge we mean a charge that is located on a body whose dimensions are much smaller than other relevant dimensions. For example, … Read more
Protection schemes can be divided into two major groupings: a) Unit schemes b) Non-unit schemes a) Unit Protection Scheme: Unit type schemes protect a specific area of the system i.e. a transformer, transmission line, generator or bus bar. The unit protection schemes are based on Kirchhoff’s Current Law – the sum of the currents entering … Read more