IEEE C37.26-2003

This guide describes three methods used to measure the power factor in 60 Hz inductive low-voltage (1000 volts and below) test circuits. Similar methods may apply at other frequencies. These methods are 1) ratio method, 2) dc decrement method, 3) phase relationship method. These preferred methods are shown in Table 1." [New scope of document] "Scope: This guide describes three methods used in the measurement of power factor of inductive low-voltage (1000 volts and below) test circuits. These methods may be used at any frequency; however, the values in the tables are specifically for 60 Hz test circuits. The three methods are: 1) Ratio Method, 2) dc decrement method, 3) Phase relationship method. Table 1 lists the preferred method to be used for different levels of test currents and for different levels of power factor. While this guide is primarily intended for use on low-voltage test circuits, the methods discussed are also usable at higher voltages." The purpose of this guide is to recommend methods of measuring the power factor for inductive test circuits, so that the preferred method giving the greatest accuracy is recommended for any particular circuit. Revision Standard - Superseded. This guide provides methods for determining the value of power factor for inductive low-voltage (1000 volts ac and below) test circuits. These methods are used in determining power factor during short-circuit current tests in high power laboratories. It is preferred that these methods be used during short-circuit current testing. Alternatively, other methods (including use of computerized or digital techniques) may be used, but the method used must have been validated as producing results equivalent to those obtained using the methods in this guide. The methods described are intended for use in low-voltage test circuits (under 1000 volts ac), but may also be used for higher voltages.