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This ability to selectively control power factor can be exploited for power factor correction of the power system to which the motor is connected. Since most power systems of any significant size have a net lagging power factor, the presence of overexcited synchronous motors moves the system's net power factor closer to unity, improving efficiency.
The equation describing the relative motion is known as the swing equation, which is a non-linear second order differential equation that describes the swing of the rotor of synchronous machine. The power exchange between the mechanical rotor and the electrical grid due to the rotor swing (acceleration and deceleration) is called Inertial response.
The power factor in a single-phase circuit (or balanced three-phase circuit) can be measured with the wattmeter-ammeter-voltmeter method, where the power in watts is divided by the product of measured voltage and current. The power factor of a balanced polyphase circuit is the same as that of any phase. The power factor of an unbalanced ...
The minimum at unity power factor () is due to the general formula for the power P of a synchronous motor, = . In order to keep the power constant, with the line voltage at the terminals of the armature V A {\displaystyle V_{A}} also constant, any decrease in power factor has to be accommodated by a corresponding increase in the armature ...
The fixed speed wind turbines without a power converter (also known as "Type 1" and "Type 2" [5]) cannot be used for voltage control. They simply absorb the reactive power (like any typical induction machine), so a switched capacitor bank is usually used to correct the power factor to unity. [7] Capability curve of a photovoltaic generator
Angle notation can easily describe leading and lagging current: . [1] In this equation, the value of theta is the important factor for leading and lagging current. As mentioned in the introduction above, leading or lagging current represents a time shift between the current and voltage sine curves, which is represented by the angle by which the curve is ahead or behind of where it would be ...
An over-excited synchronous motor has a leading power factor. This makes it useful for power-factor correction of industrial loads. Both transformers and induction motors draw lagging (magnetising) currents from the line. On light loads, the power drawn by induction motors has a large reactive component and the power factor has a low value. The ...
The effects of this modulation on voltage magnitude and phase angle is illustrated using phasor diagrams that map V R, V S, and the resistive and inductive components of V line drop. Three power factor scenarios are shown, where (a) the line serves an inductive load so the current lags receiving end voltage, (b) the line serves a completely ...