zero power factor curve

File:Synchronous machine curves.png

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The zero power factor curve (also zero power factor characteristic, ZPF, ZPFC) of a synchronous generator is a plot of the output voltage as a function of the excitation current or field using a zero power factor (purely inductive) load that corresponds to rated voltage at rated current (1 p.u.). The curve is typically plotted alongside the open-circuit characteristic.

Obtained by measuring the terminal voltage when the current has a zero power factor current using a pure inductive load that could be regulated to compensate the reactive power of the generator EMF.{{cite web | url=https://www.eeeguide.com/armature-reaction-in-synchronous-motor/ | title=Armature Reaction in Synchronous Motor | date=5 January 2016 | publisher=EEEguide – Online Electrical and Electronics Learning Site | access-date=2024-12-15 }}

The curve is obtained by rotating the generator at the rated RPM with the output terminals connected to the unity load, varying the excitation field and recording the output voltage.{{discuss}}

File:PotierTriangle.png

The ZPFC could be used together with the open-circuit saturation curve in Potier Triangle method.

The zero power characteristic is similar to the open-circuit characteristic but shifted down by $\backslash alpha$.{{clarify|date=December 2024}}