Electrical Measurement and Instrumentation, Study notes of Electrical Engineering

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Electrical Measurement and

Instrumentation

By :- Sh Gulvender

TOPICS

LCR METERS

Power Measurements in 3 phase circuit

by

(a) Two wattmeter method

(b) Three wattmeter method

Transducer

Measurements of Temperature

Advantages of an LCR meter

1. One thing that is evident is that it is compact and a

three in one sort of a measuring unit which is obviously

preferable.

2. Other than this it is also worth mentioning here that an

LCR meter is quite accurate and gives the readings with a

high precision.

3. It can also tell about the angle between the voltage

and the current measure if needed.

4. It is easy to calibrate and quick to use, the user just

needs to connect the two probes of the meter to the

DUT as shown below:

Transducer

This article is about an engineering device. For the similarly named concept in computer science, see Finite state transducer. A transducer is a device that converts energy from one form to another. Usually a transducer converts a signal in one form of energy to a signal in another. Transducers are often employed at the boundaries of automation, measurement, and control systems, where electrical signals are converted to and from other physical quantities (energy, force, torque, light, motion, position, etc.). The process of converting one form of energy to another is known as transduction.

various types of transducer

measurement of strain gauge

A strain gauge is a device used to measure strain on an object. Invented by Edward E. Simmons and Arthur C. Ruge in 1938, the most common type of strain gauge consists of an insulating flexible backing which supports a metallic foil pattern. The gauge is attached to the object by a suitable adhesive, such as cyanoacrylate.[1] As the object is deformed, the foil is deformed, causing its electrical resistance to change. This resistance change, usually measured using a Wheatstone bridge, is related to the strain by the quantity known as the gauge factor.

force measurement

In physics, a force is any interaction that, when unopposed, will change the motion of an object. A force can cause an object with mass to change its velocity (which includes to begin moving from a state of rest), i.e., to accelerate. Force can also be described intuitively as a push or a pull. A force has both magnitude and direction, making it a vector quantity. It is measured in the SI unit of newtons and represented by the symbol F. The original form of Newton's second law states that the net force acting upon an object is equal to the rate at which its momentum changes with time. If the mass of the object is constant, this law implies that the acceleration of an object is directly proportional to the net force acting on the object, is in the direction of the net force, and is inversely proportional to the mass of the object. Concepts related to force include: thrust, which increases the velocity of an object; drag, which decreases the velocity of an object; and torque, which produces changes in rotational speed of an object. In an extended body, each part usually applies forces on the adjacent parts; the distribution of such forces through the body is the internal mechanical stress. Such internal mechanical stresses cause no acceleration of that body as the forces balance one another. Pressure, the distribution of many small forces applied over an area of a body, is a simple type of stress that if unbalanced can cause the body to accelerate. Stress usually causes deformation of solid materials, or flow in fluids.

Devices

pressure measurement

Pressure measurement is the analysis of an applied force by a fluid (liquid or gas) on a surface. Pressure is typically measured in units of force per unit of surface area. Many techniques have been developed for the measurement of pressure and vacuum. Instruments used to measure and display pressure in an integral unit are called pressure gauges or vacuum gauges. A manometer is a good example as it uses a column of liquid to both measure and indicate pressure. Likewise the widely used Bourdon gauge is a mechanical device which both measures and indicates and is probably the best known type of gauge. A vacuum gauge is a pressure gauge used to measure pressures lower than the ambient atmospheric pressure, which is set as the zero point, in negative values (e.g.:

• 15 psi or - 760 mmHg equals total vacuum). Most gauges measure pressure relative to atmospheric pressure as the zero point, so this form of reading is simply referred to as "gauge pressure". However, anything greater than total vacuum is technically a form of pressure. For very accurate readings, especially at very low pressures, a gauge that uses total vacuum as the zero point may be used, giving pressure readings in an absolute scale. Other methods of pressure measurement involve sensors which can transmit the pressure reading to a remote indicator or control system (telemetry).

pressure cell

Rheology under pressure is used to simulate process conditions, to measure above the boiling point, or to prevent sample evaporation. The pressure cell specifications are therefore tailored to each application. In the petrochemical industries, high pressures of up to 1000 bar and temperatures of up to 300 °C are required, whereas work with low-viscosity solvents requires a sensitive, yet fully closed system. To cover these diverse applications, a range of different pressure cells and measuring systems is available.

Ultrasonic flow meter

Principle Density is measured according to absorption method. A radioactive source (Cs-137) contained in a lead-shield, steel- enclosed housing is mounted on one side of pipe with a scintillation detector on the opposite side. Gamma energy emitted from the source passes through the pipe and the process material. The amount of energy reaching the detector changes with the density change of the material being measured. Density is determined based on energy attenuation and fluid concentration or solid content is calculated via density