The Electrical Engr.

Characteristic Impedance or Surge Impedance is a term defined for a transmission line which tells us about the impedance that will be provided by the line to a surge flowing through it. Surge is a sudden high voltage spike which remains there for a short duration but can make an entire power system unstable. This happens either due to sudden switching or due to a lightning strike on the line.   For an ideal lossless transmission line, the surge impedance is given as the square root of line inductance to the shunt capacitance (capacitance between line and earth) i.e, sqrt(L/C). The ideal lossless line behaves as a pure inductor and hence its capacitance is zero so the surge impedance is sqrt(L/0) i.e, infinite. That's why the surge current can't flow through the line. On the other hand, the shunt capacitance is a pure capacitor and hence the impedance it provides to the surge current is sqrt(0/C) i.e, 0. So, the shunt capacitance provides a short circuit path to the surg...

We know, there are various types of three-phase connected transformers like Star-Star, Star-Delta, Delta-star and Delta-Delta. Open-Delta connected transformer is a special case of three-phase Delta connected Transformer where one phase is removed due to some fault linked to it and the transformer we are left with is called an Open-Delta Transformer or V-V Transformer. It might look like the transformer will not be working but that's not true. The transformer is able to supply the loads but at reduced capacity. Let's see, how it works and what is the reduced capacity. I am also going to discuss about the over-loading capacity of the open-delta transformer. The transformer is called V-V connected transformer because the transformer looks like the English letter 'V' after one of the phases has been disconnected.       Download PDF

Variable Voltage Variable Frequency Drive (VVVfD) is one of the best and efficient methods of starting an Induction Motor Drive as well as it provides a smooth and wide range of Torque-Speed control. It saves electrical power and provides good motor starting and running characterstics. VVVfD controls the V/f (Volt/Hz) fraction to let the motor drive achieve good Torque-Speed characterstics as required. Hence it is also called, VSD - Variable Speed Drive or AFD - Adjustable Frequency Drive or Inverter based Drive as it uses Inverter to achieve the set points.  But how VVVfD works and why it is better than various other methods of Starting and Speed Control of Induction Motor based applications. Let's discuss the Theory, Working, Advantages and Applications of a VVVfD in detail.          

 *Note: Not to be confused with Coronavirus or CoVID-19... Corona Discharge is a phenomenon that happens around a High Voltage Transmission Line in which the air surrounding the surface of the conductor glows bluish or greenish and a hissing sound is produced. Mathematically speaking, when the maximum Electric Field Intensity equals the dielectric strength of the medium around the transmission line, the voltage of the transmission line at this point is known as the Critical Disruptive Voltage. Beyond this voltage, the Corona phenomenon is seen on the line. Let's understand each of these things and what exactly is corona discharge, corona power loss and how to control it...

IC Engine or Internal Combustion Engine is the type of Engine used in automobiles. This engine detonates the air-fuel mixture inside a cylinder and the energy thus produced is converted into mechanical energy that exerts thrust on a piston inside the Engine Cylinder causing the rotation of the wheel connected or cranking. The detonation of the pressurized air-fuel mixture is done by a spark generated in the spark plug . The ignition system is an Electro-mechanical Time Controlled System that helps in accurate and adequate spark generation at the spark-plug gap. Let's understand how exactly this ignition system works and what is its working principle. A very interesting topic indeed!

L ightning followed by a thunderbolt is a common phenomenon while it's raining heavily or when it is tending to rain. Lightning strikes are one of the many natural causes common for so many deaths or injuries around the world. About 240,000 cases of lightning strike happen every year around the world and about 6000 people lose their lives every year. As of June 2020, nearly 100-120 people have already lost their lives in northern India due to lightning. But what induces these lightning strikes? Why they are lethal and common? In this article, I will try to explain the cause of lightning in a simple manner and also how to avoid it. Lightning is an electrical discharge phenomenon. Any such thing happens between two opposite electrical charges separated by a distance. The hot air from the ground rises up and cools down to form water and eventually to smaller pieces of ice (due to the freezing temperatures in the upper atmosphere). These water droplets and ice al...

Harmonics in an Electrical Machine is a great problem as it affects the maximum torque in an AC motor and maximum generated EMF in case of an Alternator. Harmonics is generated because of the non-linear behavior of the core material (the material that carries the magnetic field flux) evident from the B-H curve.  Hence elimination or mitigation of Harmonics from the machine is important. This can be done by suitably designing the machine. One such design aspect is the Distribution Factor.  There are two types of winding in an Electrical Machine, Concentrated Winding and Distributed Winding . The term 'Distribution Factor' comes from Distributed type of winding. Let's understand the difference between the two and how Distribution Factor in a Distributed Winding can help in eliminating Harmonics of nth order. Download PDF Another Design aspect responsible for mitigation of Harmonics is Pitch Factor. Click here to know more about Pitch Factor.