Potier Reactance – Synchronous Generator
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Potier Reactance – Synchronous Generator
Potier Reactance
The alternator is excited in such a way that it delivers the rated current at the rated voltage while operating at the rated speed in order to perform a Zero Power Factor test to determine potier reactance. Only two points are necessary to plot the ZPF characteristics. The first point corresponds to the maximum voltage and current that can be obtained from a scc, while the second point represents the maximum voltage and current under a zpf load. This zero power factor curve resembles an OCC, but it has been shifted vertically and horizontally by a factor of IaXL caused by the armature reaction mmf, as shown in Fig. 1.15 below.
Following are the steps to draw ZPF characteristics.
Using appropriate tests, plot OCC and SCC. Create an air gap line. Perform a ZPF test at rated voltage while fully loaded, then fix point B. The length of the line BH should be equal to the field current necessary to produce the full load current during a short circuit. To cut the OCC, draw HD parallel to the air gap line. Draw DE parallel to the voltage axis or perpendicular to HB. Now, DE stands for the IXL voltage drop,. And BE is the field current needed to cancel out the effect of the armature reaction.
Triangle BDE is called Potier triangle and XL is the Potier reactance.