Essentials of indicating instruments

In this section we will discuss certain features which are common to all electrical measuring instruments. We will first consider various torques acting on its moving system. In an indicating instrument, it is essential that the moving system is acted upon by three distinct torque (or forces) for satisfactory working. There torques are: 1. A deflecting or operating torque, Td 2. A controlling torque, Tc 3. A dampling torque, Tv. Deflecting (Or the Operating) Torque The deflecting torque, causes the moving system of the instrument to move from its zero position. It may be produced by utilizing any one of the effects of current or voltage in the ins

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CLASSIFICATION OF MEASURING INSTRUMENTS

Electrical measuring instruments may be classified into two groups: (a) Absolute (or primary) instruments. (b) Secondary instruments. Absolute Instruments • These instruments give the value of the electrical quantity in terms of absolute quantities (or some constants) of the instruments and their deflections. • In this type of instruments no calibration or comparison with other instruments is necessary. • They are generally not used in laboratories and are seldom used in practice by electricians and engineers. They are mostly used as means of standard measurements and are maintained lay national laboratories and similar institutions. • Some of the

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DEFINITIONS OF IMPORTANT TERMS

Measurement work employs a number of terms which are defined below: Measurand: The quantity or variable being measured is called measurand or measurement variable. Accuracy: It is defined in terms of the closeness with which an instrument reading approaches the true or expected (desired) value of the variable being measured. Precision: It is measure of the consistency of reproducibility (repeatability) of the measurement (i.e., the successive reading do not differ). For a given fixed value of an input variable, precision is a measure of the degree to which successive measurement differ from one another. Sensitivity: It is defined by the change in the

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Introduction to Measurements

Measurements are the basic means of acquiring knowledge about the parameters and variables involved in the operation of a physical system. Measurement generally involves using an instrument as a physical means of determining a quantity or variable. An instrument or a measuring instrument is, therefore, defined as a device for determining the value or magnitude of a quantity or variable. The electrical measuring insturment, as its name implies, is based on electrical principles for its measurement function. These days a number of measuring instruments, both analog as well as digital ones, are available for the measurement of electrical quantities like

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Clippers

A circuit which removes the peak of a waveform is known as a clipper. A negative clipper is shown in Figure below. This schematic diagram was produced with Xcircuit schematic capture program. Xcircuit produced the SPICE net list Figure below, except for the second, and next to last pair of lines which were inserted with a text editor. *SPICE 03437.eps * A K ModelName D1 0 2 diode R1 2 1 1.0k V1 1 0 SIN(0 5 1k) .model diode d .tran .05m 3m .end Clipper: clips negative peak at -0.7 V. During the positive half cycle of the 5 V peak input, the diode is reversed biased. The diode does not conduct. It is as if the diode were not t

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Classification of Clippers

Classification[edit source | editbeta] Clippers may be classified into two types based on the positioning of the diode. [1] Series Clippers, where the diode is in series with the load resistance, and Shunt Clippers, where the diode in shunted across the load resistance. The diode capacitance affects the operation of the clipper at high frequency and influences the choice between the above two types. High frequency signals are attenuated in the shunt clipper as the diode capacitance provides an alternative path to output current. In the series clipper, clipping effectiveness is reduced for the same reason as the high frequency curr

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Intro-clipper

In electronics, a clipper is a device designed to prevent the output of a circuit from exceeding a predetermined voltage level without distorting the remaining part of the applied waveform. A clipping circuit consists of linear elements like resistors and non-linear elements like junction diodes or transistors, but it does not contain energy-storage elements like capacitors. Clipping circuits are used to select for purposes of transmission, that part of a signal wave form which lies above or below a certain reference voltage level. Thus a clipper circuit can remove certain portions of an arbitrary wavef

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