Category: Electrical & Electronics Measurements
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Megohmmeter: Function & Operation
The megohmmeter or megger is a portable deflection instrument widely used to check the insulation resistance of electrical cables and equipment. In other words, a megohmmeter can be described as a high resistance measurement instrument. The instrument has a constant high-voltage source, normally produced by a hand-cranked generator. The voltage may range anywhere between 100…
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Standards Used in Measurements & Their Classifications
For anyone performing a measurement using a particular instrument, it usually matters to know whether the instrument is calibrated or not. Calibration is required, along with precision, to enable accurate measurements to be made. Calibration means observing the instrument’s performance when measuring a standard of some kind. A standard is a physical representation of the…
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Oscilloscopes: Function, Features, Applications & Selection Guide
The Function of an Oscilloscope An oscilloscope is an electronic instrument that presents a graphical display of its input voltage as a function of time. It is important to note that oscilloscopes only measure voltages not currents or resistances however it is possible to convert quantities such as current, strain, acceleration, pressure and so forth…
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Pulse Generator: Function, Operation & Applications
The Function of a Pulse Generator A pulse generator is an electronic instrument used to generate pulses for use in different types of electronic applications. Pulse generators are mainly utilized for production of pulses that are used to test applications that involve digital circuits like shift registers, counters, and so forth. Operation of the Pulse…
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Function Generator: Features & Applications
Features of Function Generators A function generator is a signal source that can produce different types of waveforms as its output signal. The most common output waveforms are: sine waves, square waves and triangular waves. Furthermore, some function generators also produce sawtooth, pulse and non-symmetrical square waves. A typical frequency range for function generators is…
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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 calibrate ac ammeters and ac voltmeters, ac supply and an ac standard instrument must be…
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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: The rotor windings are excited with an AC, inducing voltage in the stator windings. The amplitude of the output is dependent on mutual inductance between the two coils,…
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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, if the unknown input signal were gated into the counter for exactly 1 second, the…
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Basic Elements of an Electronic Instrument
An electronic instrument is made up of the following key elements: Transducer This is the first sensing element and is needed only when measuring a non-electrical quantity such as pressure or temperature. Its task is to convert the non-electrical physical quantity into an electrical signal. An example of a transducer is a thermocouple for sensing…
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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 the amplitude of the quantity being measured whereas electronic instruments typically incorporate an amplifier. DC…