42.3.3.6 The power factor of a 3-phase circuit is able to be calculated by using controlled closing so that circuits in 42.3.3.5. The power factor of the 3-phase circuit is considered to be the average of the power factors of each of the phases.42.3.3.7 The recovery voltage is to be at least equal to the rated voltage of the device. The peak value of the recovery voltage within the first complete half cycle after clearing and for the next five successive peaks is to be at least equal to 1.414 times the rms value of the rated voltage of the device. Each of the peaks is not to be displaced by more than +10 electrical degrees from the peak values of the open-circuit recovery voltage - that is, the displacement of the peak from its normal position on a sinusoidal wave. The average of the instantaneous values of recovery voltage each of the first six, half cycles measured at the 45 degree and 135 degree points on the wave is to be not less than 85 percent of the rms value of the rated voltage of the device. The instantaneous value of recovery voltage measured at the 45 degree and 135 degree points of each of the first six, half cycles is in no case to be less than 75 percent of the rmsvalue of the rated voltage of the device.42.3.3.8 If there is no attenuation or phase displacement of the first full cycle of the recovery voltage wave when compared with the open-circuit secondary voltage wave before current flow in a circuit that employs secondary closing, the detailed measurement of recovery voltage characteristics as indicated in 42.3.3.7 is not required.42.3.4 Instrumentations for test currents above 10,000 amperes42.3.4.1 The galvanometers in a magnetic oscillograph employed for recording voltage and current during circuit calibration and while testing are to be of a type having a flat (‡5 percent) frequency response from 50 - 1200 Hz. For fast acting fuses, current limiters, or motor-short-circuit protectors, a galvanometer should have a flat frequency response from 50 - 9000 Hz or an oscilloscope should be used to obtain accurate values of peak current, (lp), and energy let-through, (IRt).42.3.4.2 Galvanometers are to be calibrated as described in 42.3.4.3 - 42.3.4.6.