The Electrical Engr.

I came across a question that was asked to me quite a couple of time: When to use I²R, V²/R or VI while calculating power? At first, the question looks simple and as if it needs no formal explanation but that's not the case. Use of any of them will give the correct result provided that you apply it correctly. Correct application is possible only when you understand the type of circuit you are dealing with. Another important point is to use the one which is going to take less time and help you calculate easily. All of the three equations tell the same thing but their usage is subject to the type of problem you're trying to solve. Let us understand when, how an what to use while calculating power in an electrical circuit.

High Voltage Direct Current Transmission or HVDC Transmission is the most efficient method of power transmission over a very long distance. The reason is the various losses associated with the AC transmission over a longer distance (more than 200km). However, HVDC is a complex and costlier than AC transmission. Let us understand how HVDC works exactly and what makes it more efficient than its AC counterpart.

Current Transformer is an important instrument used in power stations and Sub-stations for stepping down the line current to a lower level. These are used mainly for metering or measurement purpose and for protection purpose. Lower current levels allow us to use low range ammeters to safely measure the respective current in the line. On the other hand, there are current transformers used for actuating Relay which in turn activates circuit breakers to separate the faulty line from the system. These type of CTs are called Protection type CT. Now, can we use a protection type CT for metering purpose and vice-versa? If not then why? Let's understand...    

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.

Harmonics is a big problem in any Electrical Machine as it affects the torque of a motor or lowers the effective Electrical power from a generator. But it can be removed effectively by taking care of a winding parameter known as "Pitch Factor". What is pitch factor and how it reduces the harmonic content in the waveform? Let's find out...

Switching off lights for 9 mins would have resulted in a blackout but Why? What's the impact of sudden unloading on Power Plants and how was it managed then? Let's find out...

Why 'mains(M)' & 'common(C)' terminals in a Wattmeter aren't connected internally by manufacturers even though in all practical applications, these terminals are required to be connected externally for measuring power and energy consumption? Know the reasons behind it.

Working of a Fluorescent Tube Light explained in Hindi in English

So, I was repairing this old LED light which had a defect in its filter capacitor. In the meantime, I wanted to find out what happens if I connect a fluorescent lamp starter with this LED circuit in series just as it is in case of a Fluorescent Lamp? So, I broke the plastic cover and took out this actual starter inside which has a capacitor* connected in parallel to. Here's what I found.     *Note: The capacitor that you see in parallel to the starter is there to force high voltage across the bimetallic strip to make the entire process faster. In a fluorescent tube, fast starting is very much important to create a huge voltage across the lamp filaments and help it getting ignited. Video on working of a Fluorescent Lamp Tube: https://youtu.be/whMsyZmwEGU Subscribe to My YouTube Channel to get more interesting and informative videos on Electrical/Electronics Engineering. 

     

Difference between Inverter and Non-Inverter Air Conditioners We all have heard about these two types of ACs, Inverter AC and Non-Inverter AC. But what exactly is the difference between them. So, today in this post I am sharing the entire technical analysis of both the types of AC so that we can understand the difference easily and accurately. Once we get to know what's inside, we will be able to differentiate between them. So, let's get started...  Inverter और Non-Inverter AC के बीच अंतर || हिंदी में

   

Ferranti Effect is seen in a long or medium distance Transmission line. When a transmission line is unloaded at the receiving end or is lightly loaded then it results in sudden swing of the receiving end voltage and that goes beyond the sending end voltage. This is called Ferranti Effect.  But what exactly causes the Ferranti Effect to take place? Why does the voltage at the recieving end swings to a value greater than the sending end voltage? Let's understand that simply with the help of a mathematical model of a Transmission line.  Download the session PDF here :  Download PDF

Touch Potential and Step Potential Explained Electrical Safety 101