Table 1: Operation statistics of main protections of China state grid in 220 kV and above power systems from 2004 to 2009.

Year200420052006200720082009Average

Line
 Total faults29411292912604724685368651234726441
 Correct diagnosed faults29181292342603024666368551234526385.17
 Diagnostic accuracy/%99.2299.8199.9399.9299.9799.9899.79

Bus
 Total faults9012011212215989115.33
 Correct diagnosed faults7711410211815688109.17
 Diagnostic accuracy/%85.5695.0091.0796.7298.1198.8894.65