Powell Electrical Manufacturing Company - Powell Industries, Inc.

The ANSI standards have evolved from the 1945revision when breakers were rated based oninterrupting MVA. In 1964, the standards establishedvarying K factors to adjust interrupting rating as afunction of the voltage. The K factor reflects theperformance of the oil and air interrupting technologiesavailable at that time.This practice ended with the 1999 change, where circuitbreaker K factors were all set at a value of one. The Kfactor of 1.0 results in all medium voltage breakers,tested to ANSI standard C37.09, having a constantinterrupting rating irrespective of nominal systemvoltage. The changes in interrupting rating at the systemvoltage can be seen in Tables 1 & 2.Table 1 Table 2Introducing...New, Expanded 63kA Interrupting Rating!Tested for 10,000 operations5 times the ANSI Standard of 2000• 36” Wide• Low Maintenance Current Transfer• Fits Into Existing PowlVac ® Switchgear• 3 Second Short Time• UL and C-UL Listed