In this module we will learn the most important principles of making electrical measurements in general, i.e., to obtain voltages and currents using the. Electrical and Electronics. Measurements and Instrumentation. Prithwiraj Purkait. Professor. Department of Electrical Engineering and. Dean, School of. Modern Electronic Instrumentation and Measurement Techniques: Helfrick & Cooper Electrical Measurement and Measuring Instruments - Golding & Waddis.
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PDF | On May 16, , Ramaprasad Panda and others published Electrical & Electronics Measurements & Measuring Instruments. Electrical Measurements and Measuring Instruments.pdf - Ebook download as PDF File .pdf), Text File .txt) or read book online. Instrumentation book. Basic Electrical Measurements. Electromechanical measuring devices. There are several advantages of traditional electromechanical instruments: simplicity.
This is a sensitive instrument which gives f. When an ammeter is required to measure currents of larger magnitude, a proportion of the current is diverted through a low-value resistance connected in parallel with the meter. Such a diverting resistor is called a shunt. The digital voltmeter DVM is one which provides a digital display of the voltage being measured. Advantages of a DVM over analogue instruments include higher accuracy and resolution, no observational or parallex errors see Section A digital multimeter is a DVM with additional circuitry which makes it capable of measuring a.
Instruments for a.
Some instruments, such as the movingiron and electro- dynamic instruments, give a true r. With other instruments the indication is either scaled up from the mean value such as with the rectifier moving-coil instrument or scaled down from Submitted By: Izhar Mithal Jiskani — 09 MN 98 Basic Electical Technology Assignment, Given By Sir Muhammad Rashid Memon Sometimes quantities to be measured have complex waveforms see Section Such waveform errors can be largely eliminated by using electronic instruments.
An ohmmeter is an instrument for measuring electrical resistance. Unlike the ammeter or voltmeter, the ohmmeter circuit does not receive the energy necessary for its operation from the circuit under test.
In the ohmmeter this energy is supplied by a self-contained source of voltage, such as a battery. Initially, terminals XX are short-circuited and R adjusted to give f.
Electrical Measurements And Measuring Instruments (1949)
Thus f. When calibrated, an unknown resistance is placed between terminals XX and its value determined from the position of the pointer on the scale.
An ohmmeter designed for measuring low values of resistance is called a continuity tester. An ohmmeter designed for measuring high values of resistance i. Multimeters Instruments are manufactured that combine a moving-coil meter with a number of shunts and series multipliers, to provide a range of readings on a single scale graduated to read current and voltage.
If a battery is incorporated then resistance can also be measured. Such instruments are called multimeters or universal instruments or multirange instruments.
A particular range may be selected either by the use of separate terminals or by a selector switch. Only one measurement can be performed at a time.
Often such instruments can be used in a. Wattmeters A wattmeter is an instrument for measuring electrical power in a circuit. The instrument has two coils: i a current coil, which is connected in series with the load, like an ammeter, and ii a voltage coil, which is connected in parallel with the load, like a voltmeter. Electro dynamic or Dynamometer type Instruments Fixed coil: The magnetic field is produced by the fixed coil which is divided into two sections to give more uniform field near the centre and to allow passage of the instrument shaft.
Moving coil: The moving coil is wound either as a self-sustaining coil or else on a nonmagnetic former.
A metallic former cannot be used, as eddy currents would be induced in it by alternating field. Light but rigid construction is used for the moving coil.
It should be noted that both fixed and moving coils are air cored. These hairsprings also act as leads of current to the moving coil.
Dampers: Air friction damping is employed for these instruments and is provided by a pair of Aluminum-vanes attached to the spindle at the bottom.
These vanes move in a sector shaped chamber. Shielding: Since the magnetic field produced by fixed coils is weaker than that in other types of instruments, these meters need a special magnetic shielding. Electro-dynamic instruments are effectively shielded from the effects of external magnetic fields by enclosing the mechanism in a laminated iron hollow cylinder with closed ends. Voltmeter Voltmeter is a kind of Galvanometer that is used for measuring voltage potential of an electric circuit or the potential difference between two points.
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Technically speaking, all Voltmeters are basically Ammeters, as they measure current rather than the voltage. Voltage gets measured only when current is transmitted in a circuit through the resistance.
No doubt Voltmeters are often termed as high resistance Ammeters. A Voltmeter is a versatile instrument as they are adept in measuring not only voltage but also current and resistance.
Electrical Measurements and Measuring Instruments.pdf
This is the reason why Voltmeter is also known as Multimeter. Types With the advent of digital electronic devices, Digital Voltmeters are now in vogue in most of the physics laboratories. Digital Voltmeters can measure the current flow in amperes and then display the voltage digitally.
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Rop Page i EEE Natural constants and their application in measurements. Primary standards.
Electrical Measurements and Measuring Instruments.pdf
Elements of a measurement system: Sources of error. Error analysis. Transducers; resistive, capacitive, inductive, optical, thermal etc. Analogue instruments. Digital instruments. Instrument transformers. Cathode ray oscilloscope CRO. Calibration of instruments.
Measurements of voltage, current, charge, resistance, inductance, capacitance, phase angle, frequency, power and energy. Magnetic measurements. Morris, , Measurement and Instrumentation Principles — 3 rd ed.
Sadiku, , Fundamentals Of Electric Circuits , 5th ed. Sadiku, , Fundamentals Of Electric Circuits , 5th ed. Tse, Ivan E. Morse , Measurement and instrumentation in engineering: principles and basic laboratory experiments , CRC Press, illustrated Ed.
Introduction to International Systems of Units Definitions of the SI Base units Derived SI units Prefixes Used For Multiples of Units Introduction to Electrical Measurement Evolution of Instruments Active and Passive Instruments Null-type and deflection-type instruments Classification of Instruments Characteristics of Instruments; What affects your measurements?
Measurement Errors Classification of Errors Systematic Errors Random ErrorsFirst it give rise to increased sensitivity, secondly i9t gives rise to increased input impedance. Calibration of instruments. The damping force ensures that the pointer comes to rest in its final position quickly and without undue oscillation. Thus f.
Morris, , Measurement and Instrumentation Principles — 3 rd ed. Digital Measuring Instruments Electrostatic voltmeters are particularly suitable in cases where voltage measurements cannot be performed using conventional contacting voltmeters. However, a meter being used to measure a.