PMMC Meter DefinitionA PMMC meter (also known as a D’Arsonval meter or galvanometer) is defined as a device that measures the current through a coil by observing the coil’s angular deflection in a uniform magnetic field.PMMC ConstructionA PMMC meter (or D’Arsonval meters) is constructed of 5 main components: Stationary Part or Magnet System Moving Coil Control System Damping System MeterWorking PrincipleA PMMC meter uses Faraday’s Laws of electromagnetic induction, where a current-carrying condu

Errors in Measurement DefinitionErrors in measurement are defined as the differences between measured values and true values.Static Error FormulaStatic error is calculated using the formula dA = Am – At, where dA is the error, Am is the measured value, and At is the true value.Limiting ErrorsThe concept of guarantee errors can be cleared if we study this kind of error by considering one example. Suppose there is a manufacturer who manufactures an ammeter, now he should promise or declare that th

What are Electrical Measuring Instruments?Electrical Measuring Instruments DefinitionAn electrical measuring instrument is a tool used to measure electrical parameters.Absolute Measuring InstrumentsAbsolute measuring instruments provide output based on the physical constants of the instruments. Examples include Rayleigh’s current balance and the Tangent galvanometer.Secondary Measuring InstrumentsSecondary measuring instruments are made using absolute instruments and are calibrated by comparing

What is the Measurement of Resistance?Resistance DefinitionResistance is the opposition to electric current flow, a fundamental concept in electrical engineering.Measurement of Low Resistance (<1Ω)Kelvin’s Double BridgeKelvin’s double bridge is a modification of simple Wheatstone bridge. Figure below shows the circuit diagram of Kelvin’s double bridge.As we can see in the above figure there are two sets of arms, one with resistances P and Q and other with resistances p and q. R is the unknown

Induction Type Meters DefinitionInduction type meters are devices used to measure electrical energy in homes and industries by using the interaction of fluxes and alternating currents.Working PrincipleThe working principle andconstruction of an induction type meter are simple and easy to understand, making them popular for measuring energy in homes and industries. In all induction meters, two fluxes are produced by different alternating currents on a metallic disc. These alternating fluxes creat

Varmeter circuit

Oscillator Transducer

Three-phase power measurement circuit

Resistance measurement circuit diagram

What is a Optical Pyrometer ?Optical Pyrometer DefinitionAn optical pyrometer is a device that measures the temperature of glowing objects by comparing their brightness to a reference light.ConstructionIt is a simple device with a lens, lamp, colored glass, eyepiece, battery, ammeter, and rheostat.Working PrincipleIt operates by matching the brightness of the lamp filament to the brightness of the hot object.CalibrationThe temperature is determined by the ammeter reading when the filament and th