Phase Sequence Indicator and Temperature Meters . monitoring and measuring electrical quantities of .. The instrument is used for monitoring, measuring. Performance specifications for direct acting indicating instruments and their accessories. DIN Scales and pointers for electrical measuring instruments . use margin of error to indicate a 95% confidence interval, corresponding to an . ISI mark on measuring instruments and items so that these may be compared.
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Presently, he is Professor, Department of Electrical Engineering and Dean, microcontroller-based numerical adaptive relay, digital instrumentation, and data measuring instrument having a calibrated scale indicating the quantity under . . Electrical Measurement and Measuring Instruments - Golding & Waddis The figures in the right-hand margin indicate marks. (Answer any six questions. Module Test Instruments & Measuring Devices . Kidwell, Walter, Electrical Instruments and Measurements, McGraw-Hill. Rev. 0 . indicated voltage. Kv.
What do I get? The physical constant means the angle of deflection, degree and meter constant. AC and DC bridges, potentiometer are the examples of this type. The null deflection instrument is used in the potentiometer and in galvanometer for obtaining the null point. The magnitude of voltages depends on the current, flux density and property of the conductor. These instruments are usually used merely to show readable deflections for the smallest current that is significant in the particular application.
Types of operating forces: Deflection force. Controlling force.
For Working of indicating instruments the torques required are i deflecting torque. The method of producing this torque depends upon the type of the instrument. Under the influence of the controlling torque the pointer or moving system will return to its zero position on removing the source producing the deflecting torque.
Without controlling system, the pointer would swing over its maximum deflected position irrespective of size of current and moreover, once deflected it would not return to its zero position on removing the current. The controlling torque in indicating instruments is created either by a spring or by gravity as given below. It the instrument is under damped the moving system will oscillate about its final position.
If the instrument is over-sampled, the moving system will become slow and lethargic and when the degree of damping is such that the pointer moving system rises quickly to its deflected position without oscillations; the damping is said to be 'critical' and the instrument is said to be " death beat".
In practice to obtain best results the damping is adjusted to the value slightly less than the critical value. In modern form of air friction damping, an aluminum vane is enclosed in the quadrant shaped recess cast in Bakelite moulding or die casting and air brake chamber is completed by a cover plate.
In this method of damping light vanes or disc are attached to a spindle of the moving system and move in a damping oil. In electrical measuring instruments, the use of eddy currents has been made as an electromagnetic breaker or damper.
The eddy current damping is the most efficient and is based on the principle that whenever as sheet of conducting but non-magnetic material like copper or aluminum moves in a magnetic field so as to cut through lines of force, eddy current are set up in the sheet. Due to these eddy currents, a force opposing the motion of the sheet is experienced between them and the magnetic field.
This force is proportional to eddy currents and the strength of the magnetic field. The eddy currents are proportional to the velocity of the moving system. Hence if the strength of the magnetic field is constant the damping force is proportional to the velocity of the moving system and is zero when the moving system is at rest. Galvanometers operate on the principle of experiencing of a force on a current carrying conductor placed in a magnetic field.
These instruments are usually used merely to show readable deflections for the smallest current that is significant in the particular application.
The main advantage of moving coil instruments lies in its freedom from the effects of stray fields and the ease with which a long and uniform scale may be had. Ammeters and Voltmeters. Wattmeter Measures the power Vectorscope Displays the phase of the colors in color TV Video signal generator Generates video signal for testing purposes Voltmeter Measures the potential difference between two points in a circuit.
Electrical and electronic measuring equipment. Arbitrary waveform generator Digital pattern generator Function generator Sweep generator Signal generator Video-signal generator. Retrieved from " https: Measuring instruments Electronic test equipment Electrical test equipment.
Namespaces Article Talk. The classification of the electric instruments depends on the methods of representing the output reading. In this article, we discuss the different types of electrical instrument.
The absolute instrument gives the value of measures quantities regarding the physical constant. The physical constant means the angle of deflection, degree and meter constant. The mathematical calculation requires for knowing the value of a physical constant. The tangent galvanometer is the examples of the absolute instruments.
In tangent galvanometer, the magnitude of current passes through the coil determines by the tangent of the angle of deflection of their coil, the horizontal component of the earth magnetic field, radius and the number of turns of wire used.
The most common applications of this type of instrument are found in laboratories. In the secondary instrument, the deflection shows the magnitude of the measurable quantities.
The output of this type of device is directly obtained, and no mathematical calculation requires for knowing their value. The digital instrument gives the output in the numeric form. The instrument is more accurate as compared to the analogue instrument because no human error occurs in the reading.
The instrument whose output varies continuously is known as the analogue instrument.