This part of the Chinese relay series carries the disturbance test in which a burst of damped oscillation is applied to the auxiliary and signal circuits of protection equipment, and it belongs to a relay standard family that was rebuilt to follow the international structure for measuring relays and protection equipment. In Chinese practice the test is applied to equipment destined for the transmission and distribution network, where the wiring of a substation produces exactly this kind of repetitive transient whenever a disconnector or a circuit breaker operates, and the results are assembled together with the power frequency, fast transient, surge and conducted radio frequency tests into a single disturbance report for the device. The standard is cited in the technical specifications of the network operators and of the equipment manufacturers who supply them, and its numbering should be read with care, since this part of the Chinese series and the corresponding part of the international relay series describe the same test under different numbers.