Indepth Electrical engineering

Synchronous machines construction depends upon type of prime mover used in machines. There are following types of prime movers used in power generation:- 1.        Steam turbines 2.        Hydraulic Turbines 3.        Diesel Engines Let’s discuss them :- 1.      Steam turbine:- These types of synchronous machines have high speed.  Generators driven by steam turbine are also called Turbogenerators. Maximum speed of Turbogenerators is 3000 RPM as per formula Frequency= PN/ 120; Where P is no. of poles N is no. of revolutions In 2 Pole machine at 50 HZ frequency Speed of Turbogenerator comes out to be= 50X120/ 2= 3000 RPM With Such high speed lower value of armature diameter is to be designed. Lower diameter is selected to limit the centrifugal forces which have very much influence on the generator design. Peripheral Speed of a Machine is given by f...

In case of synchronous machines  Armature is always placed on stator and field winding on armature as there are following advantages:- 1.      Better economy:- It is always economical to place armature winding on Stator and field winding on rotor in synchronous machines as this can be illustrated by example as below:- Consider a 3-Phase Star connected 500 MVA, 11KV synchronous machine, now its line current will be = 500X10 3                                11 X Which Will be = 26244 A Now If we place armature winding on rotor than we will required 3 slip rings each will be capable of handling such a high current of 26244A. Further Slip rings needed to be insulated from shaft for a voltage= 11/  = 6.35 KV. Also Star point needed to be brought out by using fourth slip ring which will be groun...

Cable Fault Detection Methods in Electrical Systems In electrical systems, cables are prone to faults due to insulation failure, moisture ingress, overloading, mechanical damage, or aging. Detecting and locating the fault accurately is crucial because replacing long underground cables can be expensive and time-consuming. Here are the most widely used methods of cable fault detection : 1. Megger Testing (For LT Cables) Purpose: Checks insulation resistance of low-tension cables. Process: Apply 500V/1000V DC using a Megger. Infinite reading → Cable is healthy. >100 MΩ → Acceptable (may have slight moisture, which usually dries when load is applied). 50–100 MΩ → Usable for light loads. ≈0 Ω → Faulty cable (short between conductors or between conductor and armour). 🔹 Additional Use: Resistance measurement between two terminals using Megger. 2. Hi-Pot Testing (For HT Cables) Purpose: Tests insulation strength of high-tension (HT) cables. Pro...

Effects of Low and High Voltage on Induction Motors The motor nameplate specifies the voltage range within which an induction motor is designed to operate. Operating motors outside this specified voltage range—either too low or too high—can lead to reduced efficiency, overheating, and even premature motor failure . 1. Power Equation for Induction Motors P = V × I × Power Factor P = V \times I \times \text{Power Factor} If voltage decreases , current must increase (for the same power output). If voltage increases , current may not always decrease because of magnetic saturation effects in the motor core. 2. Effects of Low Voltage on Induction Motors When the applied voltage falls below the motor’s rated range: Current increases to maintain power output. This excessive current leads to overheating and possible burnout if protection devices fail. Efficiency drops as copper (I²R) losses increase. Torque reduces since torque is proportional to the s...

Who Discovered Electricity? A Journey Through History Electricity is the backbone of modern life —from lighting our homes to running industries, everything depends on it. But have you ever wondered: Who discovered electricity and when? The answer isn’t simple. Electricity wasn’t “invented” (since it’s a natural form of energy), but rather discovered, studied, and developed by many scientists over centuries. Let’s explore how electricity evolved into the powerful force we use today. Early Discoveries of Electricity 600 BC – Ancient Greeks The Greeks noticed that rubbing fur on amber caused them to attract each other. This was the first observation of static electricity . 17th Century Developments By the 1600s and 1700s, many discoveries laid the foundation of electrical science: Invention of the electrostatic generator Understanding positive and negative charges Classification of materials into conductors and insulators Pioneers of Electricity William Gilbert (1600...

Locked Rotor Current and Torque in Induction Motors What is Locked Rotor Current? Locked rotor current (LRC) is the maximum current drawn by an induction motor when its rotor is not rotating (locked condition) . At startup, since the motor speed is zero, the slip is 1 (100%), and the motor draws its highest current. This current is usually 3–8 times the full load current (FLC) . As the motor accelerates, the current gradually reduces until it stabilizes at the rated full load current. LRC depends on the motor design, type, and supply voltage (higher supply voltage → lower current for the same power). 👉 In other words, "locked rotor current" is the current drawn if the motor is energized but prevented from turning. Equivalent Circuit at Locked Rotor Condition At locked rotor, each stator phase behaves like a series R–L circuit . Resistance (R): Copper loss component. Inductance (L): Reactance due to leakage ...

For transmission of power at High voltage Transmission lines needed to be laid. For laying Transmission lines Transmission towers are most widely used in world. Transmission towers are used for following purposes:- 1.        To separate high voltage conductors from surroundings and from each other. 2.        To keep conductors at sufficient height for safe limits. An overhead transmission line usually consists of three conductors or bundles of conductors containing the three phases of the power system. The conductors are usually aluminum cable steel reinforced (ACSR), which are steel core (for strength) and aluminum wires (having low resistance) wrapped around the core. Tower designing is most important part as towers has to sustain natural calamities.  There are following parts in Transmission towers:- 1.        Tower top 2.        Cross a...