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...

Why Armature Winding is Placed on Stator and Field Winding on Rotor in Synchronous Machines? In synchronous machines—both synchronous generators (alternators) and synchronous motors—the armature winding is always placed on the stator while the field winding is mounted on the rotor . This construction is not accidental; it offers clear technical and economic advantages. Let us analyze these reasons step by step with practical examples. 1. Better Economy of Construction If the armature winding were placed on the rotor , slip rings would need to carry very high currents at high voltages , making the system bulky, costly, and inefficient. Example: Consider a 3-phase, star-connected, 500 MVA, 11 kV synchronous generator : Line current, I = 500 × 10 6 3 × 11 × 10 3 = 26 , 244  A I = \frac{500 \times 10^6}{\sqrt{3} \times 11 \times 10^3} = 26,244 \text{ A} If this huge current were carried through slip rings, we would require 3 slip rings rated for 26.2 kA each , insulate...

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 ...

Transmission Towers: Parts, Design, and Types Explained High-voltage power transmission is the backbone of modern electricity networks. To transmit power over long distances, transmission lines are laid, and these lines are supported by transmission towers , also known as pylons. Transmission towers serve two primary purposes: To safely separate high-voltage conductors from surroundings and from each other. To keep conductors at sufficient height above the ground, ensuring safety and reliability. Most overhead transmission lines carry three-phase power using three conductors or bundles of conductors. Typically, ACSR (Aluminum Conductor Steel Reinforced) is used: a steel core provides strength, while surrounding aluminum wires offer high conductivity with low resistance. Key Parts of a Transmission Tower A transmission tower is an engineered steel structure designed to withstand natural calamities, wind loads, and conductor tensions . It is made of several essentia...