8.15.3 Setting guidelines SEMOD171741-1 v18.15.3.1 Scheme communication and tripping for faults occurring duringpower swinging over the protected line SEMOD131360-4 v2The IED includes generally up to five distance protection zones. It is possible touse one or two of them intentionally for selective fault clearing during powerswings only. Following are the basic conditions for the operation of the so called(underreaching and overreaching) power-swing zones:• They must generally be blocked during normal operation and released duringpower swings.• Their operation must be time delayed but shorter (with sufficient margin) thanthe set time delay of normal distance protection zone 2, which is generallyblocked by the power swing.• Their resistive reach setting must secure, together with the set time delay fortheir operation, that the slowest expected swings pass the impedance operatearea without initiating their operation.Communication and tripping logic as used by the power swing distance protectionzones is schematically presented in figure 228.The operation of the power swing zones is conditioned by the operation of Powerswing detection (ZMRPSB) function. They operate in PUTT or POTTcommunication scheme with corresponding distance protection zones at the remoteline end. It is preferred to use the communication channels over the optionallyavailable “Line Data Communication Module - LDCM” and the “Binary signaltransfer to remote end” function. It is also possible to include, in an easy way (bymeans of configuration possibilities), the complete functionality into regularscheme communication logic for the distance protection function. Thecommunication scheme for the regular distance protection does not operate duringthe power-swing conditions, because the distance protection zones included in thescheme are normally blocked. The powerswing zones can for this reason use thesame communication facilities during the power-swing conditions.Only one power swing zone is necessary in distance protection at each lineterminal, if the POTT communication scheme is applied. One underreaching powerswing zone, which sends the time delayed carrier signal, and one overreachingpower swing zone, which performs the local tripping condition, are necessary withPUTT schemes.The operation of the distance protection zones with long time delay (for example,zone 3) is in many cases not blocked by the power swing detection elements. Thisallows in such cases the distance protection zone 3 (together with the full-schemedesign of the distance protection function) to be used at the same time as theoverreaching power-swing zone.Section 8 1MRK 506 369-UEN BImpedance protection418 Line distance protection REL670 2.2 IECApplication manual
