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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 ...
Power factors are usually stated as leading or lagging to show the sign of the phase angle. Capacitive loads are leading (current leads voltage), and inductive loads are lagging (current lags voltage). If a purely resistive load is connected to a power supply, current and voltage will change polarity in step, the power factor will be 1, and the ...
Voltage phasor diagrams for a short transmission line serving lagging, in-phase, and leading loads. The diagrams show that the phase angle of current in the line affects voltage regulation significantly. Lagging current in (a) makes the required magnitude of sending end voltage quite large relative to the receiving end.
"Sq" current of one daytime vortex within the ionospheric dynamo region: 180 kA Typical current used in electric arc furnace for ferroalloys [11] 10 6: 1 MA High range of Birkeland current: 5 MA Flux tube between Jupiter and Io (moon) [12] 26 MA Sandia National Laboratories, Z machine approximate firing current [13] since 2007 256 MA
Voltage is designated as the base to which current angle is compared, meaning that current is thought of as either "leading" or "lagging" voltage. Where the waveforms are purely sinusoidal, the power factor is the cosine of the phase angle ( φ {\displaystyle \varphi } ) between the current and voltage sinusoidal waveforms.
The phase angle difference between voltage and current of each phase is not necessarily 0 and depends on the type of load impedance, Z y. Inductive and capacitive loads will cause current to either lag or lead the voltage. However, the relative phase angle between each pair of lines (1 to 2, 2 to 3, and 3 to 1) will still be −120°.
The neutral current can be determined by adding the three phase currents together as complex numbers and then converting from rectangular to polar co-ordinates. If the three-phase root mean square (RMS) currents are I L 1 {\displaystyle I_{L1}} , I L 2 {\displaystyle I_{L2}} , and I L 3 {\displaystyle I_{L3}} , the neutral RMS current is:
The number is in units of 30 degrees. For example, a transformer with a vector group of Dy1 has a delta-connected HV winding and a wye-connected LV winding. The phase angle of the LV winding lags the HV by 30 degrees. Note that the high-voltage (HV) side always comes before the low-voltage (LV) side, regardless of which is the primary winding.