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The working principle of the Electrodynamometer Wattmeter is very simple disturbs the main magnetic field of the Electrodynamic Wattmeter. For example, in using an electrodynamic wattmeter on direct current, two readings are taken, the direction of current flow through the instrument being reversed. Dynamometer type wattmeter works on very simple principle and this principle We know that instantaneous torque in electrodynamic type.

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Electrodynamometer Wattmeter

electrdoynamic Errors in Electrodynamometer Type Wattmeter Following are the errors in the electrodynamometer type wattmeters: In order to provide an immediate and visible elextrodynamic on any gross misalinement of the two glass panels with respect to each other, two groups of fiducial marks were etched on the panels.

A typical wattmeter in educational labs has two voltage coils pressure coils and a current coil. Let I 1 and I 2 be the instantaneous values of currents in pressure and current coils respectively.

The mechanical zero of the instrument need not be disturbed, and the deflection of the moving system is thus approximately the same, regardless of the nominal value of watts being measured. The difficulty of locating and removing the causes of this misalinement, electrodyna,ic the consequent sticking, led to the conclusion that the framework of the new instru- ment should be made of materials less subject to warping than wood and which preferably allowed some degree of vision within the instru- ment.

A current of 0. It was proposed to incorporate these characteristics in the construction of the new instrument so far as was compatible with their sometimes conflicting requirements. These current ratings are conservative on a self-heating basis and might be exceeded by moder- ate amounts with some sacrifice in accuracy if necessary.

Eddy current or skin effects in the fixed coils. The corrections to be applied to the indications of d-c measuring instruments can therefore be readily and accurately determined by using secondary standards, which have been directly compared with these primary standards, in conjunction with poten- tiometers and volt boxes.


The deflec- tion of the moving system at this position was found to be about 0. The lower suspension ribbon extends 8 in.

The “series resistance” consists of nine 1-ohm, nine ohm, nine ohm, and nine 1,ohm coils connected to four step selector switches so that any resistance from zero wwttmeter 9, ohms, in 1-ohm steps, may be connected. Such transfer instruments are used in two separate and distinct eledtrodynamic of tests: The motor was supplied from storage batteries, and the speed was adjusted to give a cycle output from each generator.

Capacitance currents in the fixed coils. Connected in parallel 10 ampresistance 0. Park, Lewis Standard Electrodynamic Wattmeter These glass panels are hinged to each other, one being stationary and the other opening and closing like a door. By referring to the wiring diagram in figure 10 and using the nota- tion indicated on the diagram, two equations wartmeter the quantity measured wattemter the wattmeter can be written. At the wattmeter end, the shield of this lead is connected through a binding post to the lower moving-coil suspension, which is also tied to the wattmeter shield.

The voltage, Ej was set at within 0.

Errors may be due to mutual inductance effects. With a constant value of current in the fixed coils and a constant voltage across the moving-coil circuit, the deflection of the wattmeter was noted during a period of 2 hours.

Arbitrary waveform generator Digital pattern generator Function generator Sweep generator Signal generator Video-signal generator.


The reason for this is that the potential coil is allowed to move whereas the current coil is kept fixed. In other projects Wikimedia Commons. Total wat- meter de- flection cm 0. They can be used for both to measure ac as well dc quantities as scale is calibrated for both. So in order to limit the current we have connected the eledtrodynamic value resistor in series with the moving coil. The zero readings of both the electrometer and the wattmeter were recorded with no current flowing and E— v a-c.


The use of any wood at all is an undoubted disadvantage.

The average deflection torque is obtained by integrating the torque from 0 to T limit. The results of tests at zero power-factor comparing the wattmeter with a quadrant electrometer are tabluated in table 2. The fixed coils were cemented into these holders with sealing wax. The output voltage of each alternator and the phase angle between their voltages electrodhnamic be varied independently.

The real power divided by wattmeteer apparent volt-amperes VA is the power factor. The value of direct current was recorded, direct voltage and current were reversed, and another value of direct current was obtained and recorded. The strength of this electromagnetic field is directly proportional to the amount of current passing through it. In electrodynamometer type wattmetermoving coil works as pressure coil. This construction minimizes zero shift and the failure of soldered joints in the moving system.

If they are not at the position of zero mutual, there will be an emf induced in them and a current will flow when their terminals are shorted, causing a eletcrodynamic towards the position of zero mutual. This transfer instrument must be such that its reading or indication is the same with direct current as with alter- nating currentor differs by a known amount.

Coils thus made have been in service 5 years now and still appear to be very solid. Wattmeters vary considerably in correctly calculating energy consumption, elctrodynamic when real power is much lower than VA highly reactive loads, e.

The wiring diagram for the equipment used in this test is shown in figure