The setting of the tEF timer must cover, with sufficient margin, the opening time ofa circuit breaker and the dead-time of a single-phase autoreclosing together withthe breaker closing time.7.3 Automatic switch onto fault logic ZCVPSOF SEMOD153633-1 v37.3.1 IdentificationSEMOD155890-2 v4Function description IEC 61850identificationIEC 60617identificationANSI/IEEE C37.2device numberAutomatic switch onto fault logic ZCVPSOF - -7.3.2 Application M13830-3 v6Automatic switch onto fault logic, voltage- and current-based function ZCVPSOFis a complementary function to impedance measuring functions, but may use theinformation from such functions.With ZCVPSOF, a fast trip is achieved for a fault on the whole line when the line isbeing energized. The ZCVPSOF tripping is generally non-directional to secure atrip at fault situations where directional information cannot be established, forexample, due to lack of polarizing voltage when a line potential transformer isused.Automatic activation based on dead-line detection can only be used when thevoltage transformer is situated on the line side of a circuit breaker.When line side voltage transformers are used, the use of the nondirectional distancezones secures switch onto fault tripping for close-in three-phase short circuits. Theuse of the nondirectional distance zones also gives a fast fault clearance whenenergizing a bus from the line with a short circuit fault on the bus.Other protection functions like time-delayed phase and zero-sequence overcurrentfunction can be connected to ZCVPSOF to increase the dependability in thescheme.When the voltage transformers are situated on the bus side, the automatic switchonto fault detection based on dead-line detection is not possible. In such cases thedeadline detection is bypassed using the breaker closing status and the switch ontofault logic is activated.1MRK 505 393-UEN B Section 7Impedance protectionLine differential protection RED650 2.2 IEC 143Application manual
