ENGINEERING ARTICLES

  Advantages of Per Unit System in Power System Analysis In electrical power engineering, the per unit (p.u.) system is one of the most widely used techniques for analyzing and modeling power systems. It is a method of expressing electrical quantities — such as voltage, current, power, and impedance — as fractions of chosen base values rather than their actual numerical magnitudes. This normalization technique provides a universal language for system calculations, minimizing errors, simplifying transformer modeling, and enabling consistency across multiple voltage levels. Because of these benefits, the per unit system is essential in fault analysis, load flow studies, transformer testing, and short-circuit calculations . ⚡ What is the Per Unit System? The per unit system is defined as: Q u a n t i t y ( p u ) = A c t u a l   V a l u e B a s e   V a l u e Quantity_{(pu)} = \dfrac{Actual \ Value}{Base \ Value} Q u an t i t y ( p u ) ​ = B a se   ...

Breaker Schemes in Substations — Types, Design, Advantages, Disadvantages, and Comparison Author: Engr. Aneel Kumar Figure 1: Infographic overview of breaker schemes commonly used in substations. Introduction The breaker scheme or busbar arrangement in a substation defines how incoming feeders, outgoing feeders, and power transformers are connected to the bus. The choice of scheme has a direct impact on system reliability, maintainability, safety, and cost . A simple bus scheme is economical but vulnerable to outages, while advanced schemes such as breaker-and-a-half or double-bus/double-breaker provide very high reliability but at much higher cost and design complexity. Engineers select breaker schemes considering fault tolerance, maintenance needs, space requirements, expansion possibilities, protection coordination, and capital investment . Below, we explain eac...

High-Frequency AC High Voltage Generation Using Cascaded Transformers Author: Engr. Aneel Kumar Figure 1: Infographic representation of cascaded transformers method for generating high AC voltages. Introduction In high voltage engineering , generating very high alternating current (AC) voltages is essential for testing equipment like insulators, circuit breakers, power cables, and other apparatus. One common and effective method for producing such voltages is the cascaded transformers method . This technique uses a series connection of specially designed test transformers , where the secondary of one transformer feeds the primary of the next. In this way, voltages are built up step by step, achieving levels in the range of hundreds of kilovolts (kV) or even megavolts (MV). Working Principle The principle of cascaded connection relies on the fact that each...

Factors Affecting Corona in Overhead Transmission Lines Author: Engr. Aneel Kumar Figure 1: Infographic illustrating the factors influencing corona discharge in transmission lines. Introduction The corona effect in overhead transmission lines is a phenomenon that occurs when the electric field intensity around conductors exceeds a critical value, causing ionization of the surrounding air. This ionization produces bluish light, hissing sound, power loss, and ozone gas. While corona may seem undesirable, it also has a few advantages such as reducing overvoltages by absorbing surges. Corona directly impacts power system efficiency, transmission losses, equipment life, and design cost . Therefore, engineers must understand the factors affecting corona in detail to ensure efficient and reliable design of high-voltage transmission systems. 1. Conductor Size (Diameter) ...

Advantages and Disadvantages of Corona Effect in Power Systems In high-voltage overhead transmission lines , the corona effect plays a critical role in system performance. Corona occurs when the air around a conductor becomes ionized due to high electric stress. While often seen as a drawback because of power losses and interference , it also provides certain engineering benefits . This article explains the advantages and disadvantages of corona effect in detail, with examples relevant to modern electrical power systems. ✅ Advantages of Corona Effect Increase in Virtual Conductor Diameter Due to corona formation, the surrounding air becomes partially conductive, increasing the virtual diameter of the conductor. This reduces electrostatic stress between conductors and minimizes insulation breakdown risks. Related Reading: Electrostatic Fields in High Voltage Engineering Reduction of Transient Surges Corona acts like a natural cushion for sudden ...

⚡ Introduction When starting large three-phase induction motors , connecting them directly to the supply (DOL starter) often causes a surge of 6–8 times the full load current . This leads to voltage dips, mechanical stress, and overheating . To address this, industries widely use the Star Delta Starter , a cost-effective and reliable method of reducing starting current. The Star Delta Starter is one of the most common reduced-voltage starters, especially for motors above 5.5 kW . It reduces the starting current to about one-third while maintaining acceptable torque for light and medium-duty applications. 👉 Related: Advantages and Disadvantages of Auto Transformer Starter Infographic: Advantages and Disadvantages of Star-Delta Starter in Motor Starting 🔧 Working Principle of Star Delta Starter The star delta starter works by initially connecting the motor in star configuration during starting. This reduces the applied voltage on each winding to 1/√3 (about...

⚡ Introduction Starting large three-phase induction motors directly on line (DOL) often leads to very high inrush current (6–8 times the full load current). This can cause voltage dips, overheating, and mechanical stress . To overcome this, industries use reduced-voltage starters such as the Auto Transformer Starter , which provides a controlled and smooth motor start. The auto transformer starter is especially useful in industries with heavy-duty motors (above 15 kW) that require high starting torque but must limit current to avoid disturbing the power supply. 👉 Related: Advantages and Disadvantages of Star Delta Starter Infographic: Advantages and Disadvantages of Auto Transformer Starter in Motor Starting 🔧 Working Principle of Auto Transformer Starter An auto transformer with tap settings (typically 50%, 65%, 80%) is connected between the motor and supply. During starting: Reduced voltage is applied through the selected tap. Mo...