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In synchronous machines, the V curve (also spelled as V-curve) is the graph showing the relation of armature current as a function of field current in synchronous motors keeping the load constant. The name comes from an observation made by W. M. Mordey in 1893 that the curve resembles a letter V. [1]
In a synchronous generator, [1] the short circuit ratio is the ratio of field current required to produce rated armature voltage at the open circuit to the field current required to produce the rated armature current at short circuit. [1] [2] This ratio can also be expressed as an inverse of the saturated [3] direct-axis synchronous reactance ...
Armature reaction is essential in amplidyne rotating amplifiers. Armature reaction drop is the effect of a magnetic field on the distribution of the flux under main poles of a generator. [5] Since an armature is wound with coils of wire, a magnetic field is set up in the armature whenever a current flows in the coils.
Synchronous impedance curve (short-circuit characteristic curve), showing armature current as function of field current. The curve is obtained by rotating the generator at the rated RPM with the output terminals shorted and the output current going to 100% of the rated for the device (higher values are typically not tested to avoid overheating).
The rating of a brushless motor is the ratio of the motor's unloaded rotational speed (measured in RPM) to the peak (not RMS) voltage on the wires connected to the coils (the back EMF). For example, an unloaded motor of K v {\displaystyle K_{\text{v}}} = 5,700 rpm/V supplied with 11.1 V will run at a nominal speed of 63,270 rpm (= 5,700 rpm/V ...
What is a good current ratio? The ideal current ratio varies by industry. However, an acceptable range for the current ratio could be 1.0 to 2. Ratios in this range indicate that the company has ...
These current and voltage values can be obtained from the open-circuit saturation curve and the synchronous impedance curve. [11] The synchronous reactance is a sum of the leakage reactance and the reactance of the armature itself (): = +. [12]
The minimum armature current corresponds to the point of unity power factor (voltage and current in phase). As in a synchronous motor, the stator of the machine is connected to a three-phase supply of voltage V s {\displaystyle V_{s}} (assumed to be constant), and this creates a rotating magnetic field within the machine.