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.”