Alternating Current

Maintenance of Power Transformer – Transformer Diagnostic and Monitoring Introduction Being transformers static machines without any moving and turning parts, they are very reliable machines, and if maintained properly, can last for 40 years or more. Also they do not trip or blow when oven-stressed (except under extreme conditions), transformers are frequently overloaded and allowed to operate well beyond its …

An Overview of Emergency Generator Set (Manuel Bolotinha) Introduction to Emergency Generator Set Hospitals, airports, shopping malls and office buildings, just to mention some examples, are very sensitive, in what concerns safety of people and goods, to power outages caused by faults in medium (MV) and low voltage (LV) distribution networks and even in high voltage (HV[1]) transmission networks. When …

Short Circuit Currents And Symmetrical Components (Manuel Bolotinha) Short Circuit Faults and Currents Short-circuits can occur phase-to-phase and phase-to-earth, mainly due to: Dielectric breakdown of insulating materials (ageing, severe overheating and overvoltages, mechanical stress and chemical corrosion are the main factors for dielectric breakdown) Decrease of creepage distance (the shortest path between two conductive parts – or between a conductive …

How to Prevent the high Inrush Current in Capacitor Switching? Introduction to High Inrush Current in Capacitor Switching Applications of capacitance switching are not only restricted to capacitive currents but they have their implementation in energizing process of capacitors banks, overhead lines and cables. Capacitors banks switching are known to be cause of very large value of transient voltage across …

Three Phase Current Values in a 3-Phase System The following points may be noted for understanding the division of Three Phase Current in a 3-Phase System       1.  The arrow symbols shown alongside three phase current (IR, IY and IB) in fig 1 and 2 does not indicate the currents directions in a particular moment but shows the current directions …

 Advantages of Power factor improvement and Correction: Following are the merits and benefits of improvedPower factor; Increase in efficiency of system and devices Low Voltage Drop Reduction in size of a conductor and cable which reduces cost of the Cooper An Increase in available power Line Losses (Copper Losses) I2R is reduced Appropriate Size of Electrical Machines (Transformer, Generators etc) …

Ohm’s Law The relationship between Current through and Voltage across a conductor was first discovered by a German scientist George Simon Ohm. This relationship is called Ohm’s Law and be stated as; The Current “I” flowing through a conductor is directly proportional to the potential difference i.e. Voltage “V” across its ends provided the physical conditions (i.e. temperature, strain, etc) do …

 Alternating Current Library A (50/60 Hz) Transformer. Which one will give more Output? (When operates on 50 or 60 Hz frequency A Very Simple Generator / Alternator (Dynamic Model from Trash) Active, Reactive, Apparent and Complex Power. Simple explanation with formulas All about Power Factor, Disadvantages and improvement Basic Electrical Formulas Capacitors(MCQs with Explanatory Answers) Electrical Formulas AC & DC …

Calculate & Find the Rating of Single Phase & Three Phase Transformers in kVA We know that, Transformer always rated in kVA.  Below are the two simple formulas to find the rating of Single phase and Three phase Transformers. Find Rating of Single Phase Transformer Rating of Single Phase Transformer: P = V x I. Rating of a single phase …

Power Factor (Cosθ) – Cos fi or P.f In Electrical Engineering, Power Factor is only related to AC Circuits i.e. There is no Power Factor (P.f)  in DC Circuits due to zero frequency. Power Factor may be defined by three definitions and formals as follow. You may also read: Is Reactive Power Useful? 1).  The Cosine of angle between Current …