## LVDT – Construction and Working Principle

What is LVDT? Linear Variable Differential Transformer, LVDT is the most used inductive transducer for converting translating linear motion into electrical signal. This transducer converts a mechanical displacement proportionally into electrical signal. Construction: LVDT is a transformer consisting of one primary winding P and two secondary winding S1 & S2 mounted on a cylindrical former. The two … Read more

Definition: Phantom Loading is a loading condition in which an energy meter is connected to factious or phantom load for testing of energy meter with high current rating. Such loading is favorable to avoid wastage of energy during the test of measurement instrument. Testing of energy meters are carried out to verify the actual registration … Read more

## Current Transformer – Construction, Phasor and Errors

Current Transformer is an instrument transformer which steps down high value of current to a low value of current suitable for measurement devices. It is widely used in power system for measurement and protection purpose. We cannot think of power generation, transmission or distribution without using Current Transformer. Construction of Current Transformer (CT): There are … Read more

## Calculation of Multiplication Factor of Energy Meters

Energy Meters are one of the important instrument to account for energy imported / exported in an industry. In Power Generating Stations, the cumulative reading of such energy meters are used for the calculation of total Million Units (MUs) of energy exported. On the basis of MUs, total revenue generated by the Station is calculated. … Read more

## Strain Gauge and Gauge Factor

Strain Gauge is basically a sensor used for the measurement of various physical parameters like stress, strain etc. The working principle of strain gauge is based on Piezoresistive Effect. This is why it is also often called Pizoresistive Gauge. When a metal conductor is stretched or compressed, the dimension of conductor changes. Change in dimension … Read more

## Accuracy Limit Factor of Current Transformer

Accuracy Limit Factor of Current Transformer is a very important factor while selecting a CT for protection purpose. A current transformer chosen for protection purpose are defined by protection class ‘P’. The whole and sole requirement of a protection class CT is to maintain its measurement accuracy during fault as well as abnormal condition. Such … Read more

## Instrument Safety Factor of Current Transformer

Instrument Safety Factor Instrument Safety Factor (ISF) is defined as the ratio of CT saturation current to its rated current. Suppose the CT ratio is 2000/1 and the CT gets saturated if there is flow of 10 kA current through its primary, then Instrument Safety Factor is given as Instrument Safety Factor, ISF = CT … Read more

## Why PT/VT Secondary Terminal should not be Shorted?

Before discussing “Why PT/VT Secondary Terminal should not be Shorted?”, it is good to have a brief idea of Potential Transformers / Voltage Transformers. PTs/VTs are Instrument Transformer used for the purpose of protection and measurement. The construction of PT/VT is same as that of power transformer except for insulation level, cooling, sealing etc. PTs … Read more

## Core Balance Current Transformer

Core Balance Current Transformer or CBCT is a ring type current transformer through center of which a three core cable or three single core cables of three phase system passes. This type of current transformer is normally used for earth fault protection for low and medium voltage system. A typical Core balance Current Transformer is … Read more

## Ammeter Shunt –Construction and Calculation

Ammeter Shunt is used for the measurement of heavy current using an Ammeter. Ammeter Shunt is basically a low resistance connected in parallel with the moving coil so that most of the current is bypassed by the Shunt and hence only a small current flows through the moving coil. Why do we need Ammeter Shunt … Read more