Category: Electrical & Electronics Measurements
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How to Calibrate an AC Ammeter & an AC Voltmeter
An instrument calibration is performed by comparing its reading with that of a more accurate instrument when both instruments are measuring the same quantity. In this case, the more accurate instrument is employed as a standard for comparison purposes. To … Read more
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The Principle of Operation of an Induction Potentiometer
An induction potentiometer is a rotary type linear-variable inductor with two concentrated windings wound on the stator and on the rotor as illustrated in the figure below: Fig: Induction Potentiometer The rotor windings are excited with an AC, inducing voltage … Read more
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The Principle of Operation of a Digital Frequency Meter
A frequency meter/counter is a digital instrument that can measure and display the frequency of any periodic waveform. Its operation is based on the principle of gating the unknown input signal into the counter for a predetermined time. For instance, … Read more
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Basic Elements of an Electronic Instrument
An electronic instrument is made up of the following key elements: Transducer Signal modifier Indicating device Fig: Elements of an Electronic Instrument Transducer This is the first sensing element and is needed only when measuring a non-electrical quantity such as … Read more
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Electrical vs. Electronic Instruments
Despite the fact that both electrical and electronic instruments measure electrical quantities like voltage and current, they differ from each other in terms of the built-in features; for example, purely electrical instruments don’t possess any in-built amplifying device to increase … Read more
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Optical Time Domain Reflectometer (OTDR)
The commonly employed technique for analysing the state of a fibre optic is to test it with an Optical Time Domain Reflectometer (OTDR). The OTDR uses backscattered light of the fibre to imply loss. The OTDR works is similar way … Read more
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Basic Features of a DC Potentiometer
A potentiometer is an instrument that is used for measurement of potential difference across a known resistance or between two terminals of a circuit or network of known characteristics. A potentiometer is also used for comparing the emf of two … Read more
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Features and Applications of Instrument Transformers
Instrument transformers are used in the measurement of voltage, current, energy, and power in ac circuits. The main reasons why instrument transformers are employed in measurements are: To extend (multiply) the range of the measuring instrument. To isolate the measuring … Read more
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Power Measurement in AC Circuits (Single-phase & Polyphase Systems)
Introduction to AC Power Measurement In alternating current circuits, the instantaneous power varies continuously as the voltage and current varies while going through a cycle. In this case the power at any instant is given by: p(t) = v(t) x … Read more
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Performance Characteristics of Digital Measurement Instruments
In this article, we discuss the performance characteristics of digital instruments i.e. ResolutionAccuracyLinear errorsSettling timeTemperature sensitivityMonotonicity Resolution This is defined as the smallest increment in voltage that can be discerned. It is the reciprocal of … Read more