![]() In an ac-dc transfer test of a wattmeter that is neither magnetically shielded nor of astatic construction, the reading of the standard instrument may be several percent waattmeter for one direction of current and voltage than for the reversed direction also, the a-c reading may be slightly different from the d-c readings. ![]() The supply voltage applies to the moving coil. The summation of the torques produced by eddy currents in indi- vidual turns of the moving coils tends toward zero and would be exactly zero with the moving coils in the position of zero mutual inductance with the fixed coils if the fixed-coil flux were uniform throughout the area occupied by the moving coils. ![]() Imperfection of the astatic construction of the wattmeter results- in a small deflection of the moving system with direct current through the moving coils only, because of interaction with the earth’s magnetic field.Įrrors may be due connections. This material should wartmeter itself to a sufficiently sturdy and permanent construction to avoid future diffi- culties resulting from warping of the instrument frame and consequent sticking of the moving system. The investigation to determine the accuracy of this instrument for alternating- current testing at frequencies up to 2, cycles per second is described and the results are given. The current coils are connected in series with the circuit, while the potential coil is connected in parallel. These coils are named according to the convention because the current of the circuit passes through the current coil and the voltage is dropped across the potential coil, also named as the voltage coil. Wattmeter – WikipediaĪ one-piece brass cover is bent up to fit over the top, back, and two eoectrodynamic. ![]() Eddy current or skin effects in the fixed coils. The lower suspension ribbon extends 8 in. ![]() Dynamometer type wattmeter works on very simple principle and this principle We know that instantaneous torque in electrodynamic type. For example, in using an electrodynamic wattmeter on direct current, two readings are taken, the direction of current flow through the instrument being reversed. The working principle of the Electrodynamometer Wattmeter is very simple disturbs the main magnetic field of the Electrodynamic Wattmeter. ![]()
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