If two coils are connected such that, current proportional to the load voltage, flows through one coil and current proportional to the load current, flows through another coil, the meter can be calibrated directly in watts. An electrodynamometer is an instrument used for measuring the electric power. It provides a comprehensive coverage of each topic in the syllabus selection from electronic measurements and instrumentation book. The fixed coils or field coils are connected in series with. Design, commissioning and testing of an electrodynamometer.
Most of the commercial eds are comprised by a load machine which is operated by means of a torque control which is independent of the dynamics of the traction machine speed. Classification, absolute and secondary instruments, indicating instruments, control, balancing and damping, constructional details, characteristics, errors in measurement, ammeters, voltmeters. Deflection of the movable coil as current is applied 12 724. Dynamometer type wattmeter construction and working. The fixed coils or field coils arc connected in series with the load and so carry the current in the circuit. Also, on analog wattmeters, the potential coil carries a needle that moves over a scale to indicate. Electrodynamometer definition of electrodynamometer at. This type of instrument can be used either as an ammeter or as a voltmeter, but is. An electrodynamometer as defined in claim 1, wherein said variable source of direct current comprises an alternating current source having a first and a second terminals, a variable autotransformer having one terminal connected to the first terminal of said alternating current source and an intermediate movable tap, a voltagelimiting resistor.
Ncert books pdf free download for class 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, and 1 april 14, 2020 by kishen 16 comments there are many books in the market but ncert books stand alone in the market. Current flow in either direction through the three coils causes a magnetic field to exist between the field coils. An electrodynamometer ed is aimed to emulate mechanical loads to test electrical machines. The electrodynamometer is made of a squirrelcage rotor fitted in a dcexcited stator. How can a darsonval meter movement be adapted for use as an ac meter. Some meter movements can be used for both ac or dc measurements, but in general, each meter movement is best suited for a particular type.
Electrodynamometer type wattmeter electrical study app. Electrodynamometer definition, an instrument that uses the interaction between the magnetic fields produced by the currents in two coils or sets of. Dynamometer type moving coil instruments in this instrument the permanent magnet is replaced by one or two fixed coils which carry current to be measured or a current proportional to the voltage to be measured and which are connected either in series or parallel with the moving coil. For more details about electrical measuring instruments and classification of instruments click here. The basic principle was laid out in an 1848 paper by wilhelm weber 18041891. Unlike a pmmc instrument, the electrodynamometer type instrument has nonuniform scale. A study of the electrodynamometer by seiler, eleanor frances. Mechanical loading is achieved by increasing the stator field current, which generates eddy currents in the driven rotor. The electrodynamometer is basically that described by christensen et al. Electrodynamometer type wattmeter working principle. Complete gauges not only sense the pressure but indicate them on a dial or scale. The current in the moving coil causes it to act as a magnet and exert a turning force against a spring.
Electrodynamometer like the d arsonval meter, electrodynamometer is a currentsensitive device the pointer deflects up scale because of the current flow through a moving coil electrodynamometer can be used to measure both dc or ac current or voltage in addition, it can be used as a wattmeter, varmeter, power factor meter and frequency meter. The two coils are connected in different circuits for measurement of power. Due to this characteristic of the electrodynamometer movement, it can be used in both ac and dc systems to measure current. As we know that the deflection in electrodynamometer type ammeter and voltmeter is given as o ki2dmdo for ammeter and o kv2dmdo for voltmeter therefore, if dmdo is. Dynamometer type wattmeter works on very simple principle and this principle can be stated as when any current carrying conductor is placed inside a magnetic field, it experiences a mechanical force. Now, only very very slow oscillations from your hand will cause the mass to move. The moving coil and pointer, which are attached to the coil, are suspended between and connected in series with the two field coils. The stator is trunnionmounted on ball bearings and rotates against a helicoidal spring to oppose braking torque. The primary advantage of the electrodynamometer type meter movement is that it can be used to measure alternating as well as direct current. The general circuit diagram of single phase electrodynamometer power factor meter is given below. The shape of scale of this instrument depends on the variation of dmdo i. It is one of the simple and most used instrument on board with sophisticated names. Electronic measurements and instrumentation provides a comprehensive blend of the theoretical and practical aspects of electronic measurements and instrumentation. However, its most important use is in the wattmeter, which will be discussed later in this module.
Nonuniform scale of electrodynamometer type instrument. They are used on board to assist in regular maintenance of electrical equipment or when precise measurements are required. The device consists of a pair of fixed coils, known as current coils, and a movable coil known as the potential coil the current coils are connected in series with the circuit, while the potential coil is connected in parallel. Electrical measuring instruments and classification of. The traditional analog wattmeter is an electrodynamic instrument.
Mechanical movement is produced with the following elements. Darsonval, electrodynamometer, and the moving iron vane. Publication date 190704 topics alternatingcurrent research, apparatus and instruments, measurements and use of instruments, condensed matter, electronic structure, electrical, magnetic, and optical properties. An instrument, having a fixed and a moveable coil, that measures the power flowing in an electric circuit, a type of wattmeter electrodynamometer. Dynamometer type wattmeter works on very simple principle and this principle can be stated as when any electric current carrying conductor is placed inside a magnetic field, it experiences a mechanical force. Now the pressure coil is split into two parts one is purely inductive another is purely resistive as shown in the diagram by resistor and inductor. Now even slow movement of the mass is difficult because the damping viscosity of the molasses prevents motion. The fixed coils or field coils are connected in series with the load and so carry the. Pressure sensors either convert the pressure into mechanical movement or into an electrical output. Instead, the meter will vibrate at or near the zero reading. Ac and dc meters and kirchoffs laws linkedin slideshare.
What are two methods used to damp a meter movement. Basics of electrical engineering ac and dc meters kirchhoffs laws by ms. Publication date 1916 topics electrodynamometer, theses collection. The electrodynamometer movement meter has the same basic operating principle as the darsonval meter movement, except that the permanent magnet is replaced by fixed coils.
The electrodynamometer movement has the same basic operating principle as the darsonval meter movement, except that the permanent magnet is replaced by fixed coils. Electrodynamometer definition is an ammeter or galvanometer in which the torque due to the reaction between two coils in series with each other is balanced by a spiral spring. The following figure shows the dynamometer wattmeter for measuring the power. It uses for measuring the power of both the ac and dc circuits. Electrodynamometer definition of electrodynamometer by. The action of the vane against the air in the chamber opposes the coil movement and damps the oscillations. We will discuss electrodynamometer type wattmeter working principle and its construction. Before we study the internal construction of electrodynamometer wattmeter, it very essential to know the principle of working of electrodynamometer type wattmeter. Electrodynamometer type instruments alternating current. The issue of damping is different and you can imagine trying to do the above experiment with the mass sitting in a container of molasses.
Ncert books pdf download 2020 for class 12, 11, 10, 9, 8. If the current is reversed, the field polarity and the polarity of the moving coil reverse at the same time, and the turning. These instruments are similar in design and construction to electrodynamometer type ammeters and voltmeters. Electrodynamometer wattmeters these instruments are similar in design and construction to electrodynamometer type ammeters and voltmeters.
For the love of physics walter lewin may 16, 2011 duration. The former is proportional to the velocity of movement of the conductor, and thus, if the magnetic field is constant, the damping force is proportional to the velocity of the moving system and is zero when there is no movement of the system. Power factor meters electrodynamometer type power factor. All content on this website, including dictionary, thesaurus, literature, geography, and other reference data is for informational purposes only. Some voltmeters and ammeters use the electrodynamometer. All three electrodynamometer coils in series 14 724. If you apply alternating current to the standard galvanometertype meter, it will not produce a usable reading.
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