Blondel’s theorem | Power in Poly-Phase System

Statement Blondel’s theorem states that if a network is supplied through P conductors, the total power is measured by adding the readings of P wattmeters so arranged that a current element of a wattmeter is in each line and the corresponding voltage element is connected between that line and a common point. Note: If the … Read moreBlondel’s theorem | Power in Poly-Phase System

Wheatstone Bridge | Working Principle & Applications

A Wheatstone bridge is used for the accurate measurement of resistance. The Wheatstone bridge works on the principle of null deflection, i.e. the ratio of their resistances are equal, and no current flows through the galvanometer. The general arrangement of Wheatstone bridge circuit is shown in the fig. 1. It is a four arms bridge circuit … Read moreWheatstone Bridge | Working Principle & Applications

Difference Between Current & Potential Transformer

The differences between Current Transformer (CT) and Potential Transformer (PT) are given below: S.No. Current Transformer (CT) Potential Transformer (PT) 1. It is connected in series with the power circuit. It is connected in parallel with the power circuit. 2. Its secondary is connected to an Ammeter. Its secondary is connected to a Voltmeter. 3. Its secondary … Read moreDifference Between Current & Potential Transformer

Measurement of Medium Resistance

Resistance is classified into three categories as low, medium and high resistance. Medium Resistance ranges from 1Ω to 0.1 MΩ. The different methods used for the measurement of Medium resistance are as follows: Ammeter Voltmeter method Substitution Method Wheatstone Bridge Method Ohmmeter Method Substitution Method In this section, we will learn about Measurement of Medium Resistance by Substitution Method. … Read moreMeasurement of Medium Resistance

Measurement of Low, Medium & High Resistance

Resistance is classified into three categories for the sake of Measurement. Different categories of Resistance are measured by the different techniques. They are classified as Low Resistance: Resistance having value 1Ω or below are kept under this category. Medium Resistance: This category includes Resistance from 1Ω to 0.1 MΩ. High Resistance: Resistance of the order of … Read moreMeasurement of Low, Medium & High Resistance

Permanent Magnet Moving Coil or PMMC Instruments

PMMC stands for Permanent Magnet Moving Coil. PMMC Instruments are the most accurate type for the measurement of DC current or voltage. Construction of PMMC Instruments Permanent Magnet Moving Coil or PMMC Instruments consists of following components: Moving Coil Magnet System Control Spring Damping Pointer and Scale 1. Moving Coil The moving coil made up … Read morePermanent Magnet Moving Coil or PMMC Instruments

Single Phase Electrodynamometer Power Factor Meter

Construction The construction of a single phase Electrodynamometer Power Factor Meter is shown in fig. 1. It consists of a fixed coil which acts as the current coil. This coil is split up into two parts and carries the current of the circuit under test. Therefore, the magnetic field produced by this coil is proportional to the main current. Two identical pressure coils A … Read moreSingle Phase Electrodynamometer Power Factor Meter

Digital Frequency Meter | Block Diagram & Working

Functional Block diagram of Digital Frequency Meter Working principle of Digital frequency meter 1. The unknown frequency signal is fed to the Schmitt trigger. The signal may be amplified before being applied to Schmitt trigger. 2. In a Schmitt trigger, the signal is converted into a square wave with a very fast rise and fall times, … Read moreDigital Frequency Meter | Block Diagram & Working

PMMC & Dynamometer Instruments Construction Difference

Difference between the construction of PMMC and dynamometer instruments PMMC (Permanent moving magnet coil) Instrument (1) Moving Coil: The moving coil is wound with many turns of enamelled or silk-covered copper wire. The coil is mounted on a rectangular aluminium former which is pivoted on jewelled bearings. The coils move freely in the field of … Read morePMMC & Dynamometer Instruments Construction Difference

Phototransistor | Symbol, Operation and Applications

The phototransistor is a semiconductor light sensor formed from a basic transistor with a transparent cover that provides much better sensitivity than a photodiode. It is basically a 3-layer semiconductor device which has a light-sensitive base region. The base senses the light and converts it into the current which flows between the collector and the … Read morePhototransistor | Symbol, Operation and Applications

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