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...