## What is Islanding in Power System?

Islanding in Power System: Islanding is the intentional isolation of a part of power system during external widespread grid disturbance.  This isolated part of Grid is called Island. Such a disturbance may lead to black out. Therefore, islanding scheme provides a mean to continue to supply power to the essential services in a zone or … Read more

## Composite Error of CT – Definition, Calculation & Formula

Definition: Composite Error of a Current Transformer (CT) is defined as the rms value of difference between the ideal secondary current and the actual secondary current. It includes ratio error, phase error and the effect of harmonics present in the exciting current. Composite error is used to express the accuracy of protection class CT. You … Read more

## Effect of CT Burden on its Accuracy and ISF

Burden of CT is defined as the volt ampere loading which is permissible without errors exceeding the limits for an assigned accuracy class. It is expressed as volt ampere (VA). In simple words, it is the load connected to CT secondary. CT burdens are specified as 10 VA, 15 VA, 20 VA, 30 VA. You … Read more

## Earth and Unearth Cable – Introduction and Differences

Earth and Unearth cables are two types of power cables. The selection of cable is decided on the basis of system in which it is to be used. There are two different types of system on the basis of neutral earthing: Earth and Unearth System. Cable used in system where the neutral is grounded is … Read more

## Double Bus Single Breaker Scheme

Double Bus Single Breaker Scheme is also known as Main cum Transfer Bus Scheme. In this scheme, two bus bars, four Isolators / Disconnect Switch, One Earth Switch and one Circuit Breaker is used in one Bay for switching purpose. What is Bay? You will come to know this terminology latter in this article. This … Read more

## Penalty Factor – Definition, Formula and Solved Examples

What is Penalty Factor? Penalty Factor in Power System is a factor (greater than unity) by which the incremental cost of power production of plant must be multiplied to accommodate for the transmission losses. It is also defined as the ratio of power generated by the plant to the actual power demand of the load … Read more

## Difference between Harmonics and Sub-harmonics

Harmonics in electrical system is the signal having frequency which is integral multiple of fundamental frequency. This means, if the frequency of fundamental component is 50 Hz, then the frequency of harmonics will be 2×50 (=100 Hz), 3×50 (=150 Hz) and so on. If the frequency of harmonics is even multiple of fundamental frequency then … Read more

## Power Factor Improvement Principle and Correction Methods

Low power factor is mainly due to the inductive loads. In industries, mostly inductive loads are used like induction motors, lamps etc.for various purposes. These inductive loads take lagging current and hence results in low power factor. Low power factor has many disadvantages. Therefore, power factor improvement is necessary to get rid of problems associated … Read more

## Calculation of Voltage Distribution with Grading Capacitor

Grading capacitor is used in EHV circuit breakers for achieving uniform voltage distribution across the contacts of multi-break circuit breaker. Multi-break circuit breaker here means that a single breaker having more than once interrupter unit. These capacitors are connected in parallel with each of the interrupter unit. In this post, we will discuss the effect … Read more

## Triplen Harmonics – Why are they in phase?

Definition: Triplen harmonics are the odd integral multiple of third harmonic wave. If the frequency of third harmonic wave is ω then frequency of triplen harmonic wave will be 3nω, where n = 3,5,9,…These waves posses a special characteristics and hence it becomes important for the study and analysis of power system. The amazing property … Read more