DefinitionInstruments that utilize a permanent magnet to generate a stationary magnetic field within which a coil moves are known as Permanent Magnet Moving Coil (PMMC) instruments. They operate on the principle that torque is exerted on a moving coil situated in the magnetic field of a permanent magnet. PMMC instruments provide accurate results for direct current (DC) measurements.Construction of PMMC InstrumentThe moving coil and the permanent magnet are the key components of a PMMC instrument

In an electrical power system, various devices are utilized to enhance power factor and operational efficiency. Shunt capacitors and shunt reactors represent two distinct components designed to optimize the performance of electrical grids. This article explores their key differences, beginning with an overview of their fundamental principles.Shunt CapacitorsA shunt capacitor refers to a single capacitor or a group of capacitors (termed a capacitor bank) connected in parallel to the power system.

For long-distance electrical power transmission, the voltage and current levels are extremely high, making direct measurement with conventional meters impossible. Instrument transformers, including current transformers (CTs) and potential transformers (PTs), are used to step down these levels to safe magnitudes, enabling measurement with standard meters.What is a Transformer?A transformer is an electrical device that transfers energy between circuits via mutual induction. It consists of two magn

DefinitionInstruments in which the measured quantity generates physical effects that deflect or displace the moving system are known asdeflection-type instruments. In other words, these instruments use the deflection of a moving component as the basis for measuring electrical quantities, making them suitable for dynamic condition measurements.Deflection-type instruments incorporate opposing effects that counteract the displacement of the moving system. These opposing effects are designed such th

DefinitionA hygrometer is used to measure the humidity in the surrounding environment, where "humidity" refers to the amount of water vapor in a gas. Hygrometers operate on the principle that the physical properties of materials change in response to humidity, enabling measurement.Humidity is classified into two types:Absolute Humidity: Represents the amount of water vapor per unit volume of air.Relative Humidity: The ratio of the actual water vapor pressure to the maximum water vapor pressure a

DefinitionA photoelectric transducer is a semiconductor device that converts light energy into electrical energy. It employs a photosensitive element that emits electrons when struck by light, altering the element’s electrical properties and inducing a current proportional to the intensity of the absorbed light.The schematic below illustrates the structure of the semiconductor material.A photoelectric transducer absorbs light radiation incident on its semiconductor material. This absorptio

DC Potentiometer Method for Resistance MeasurementThe DC potentiometer method is employed to measure low-value unknown resistances by comparing them with a standard resistance. This involves measuring the voltage drops across both the known (standard) and unknown resistances, then determining the unknown resistance through comparison.To understand this, consider the circuit diagram:Rrepresents the unknown resistance to be measured.Sis the standard resistance against whichRis compared.A rheostat

DefinitionA Platinum Thermal Resistance (PTR), also known as a Platinum Resistance Thermometer (PRT), utilizes platinum as the sensing material to measure temperature. Its operation is grounded in the principle that the electrical resistance of platinum varies predictably with temperature changes. This type of thermometer is capable of accurately measuring temperatures within a wide range, from -200°C to 1200°C.Platinum, an inert metal, possesses excellent malleability, allowing it to be

DefinitionAHot Wire Anemometeris a device used to measure thevelocity and direction of a fluid flowby quantifying the heat loss from a heated wire exposed to the fluid stream. The wire is heated via an electric current, and its temperature change—caused by heat transfer to the fluid—serves as an indicator of flow characteristics.When the heated wire is placed in the fluid stream, heat is convected from the wire to the fluid, causing the wire’s temperature to drop. Thechange in

Measuring Instruments: Definition, Classification, and CharacteristicsA measuring instrument is a device used to quantify physical and electrical quantities. The concept of measurement fundamentally involves comparing two quantities that share the same unit. One of these quantities has an unknown magnitude, which is then compared against a predefined standard value. Through this comparison, a numerical result is obtained, representing the measured value of the unknown quantity.Measuring instrume