then invertion is necessary (InvertCTCurr = Enabled), provided that the CT’s actual
direction complies with ABB recommendations, as shown in Table 32.
8.18 Automatic switch onto fault logic ZCVPSOF
8.18.1 Identification
Function description IEC 61850
identification
IEC 60617
identification
ANSI/IEEE C37.2
device number
Automatic switch onto fault logic ZCVPSOF - -
8.18.2 Application
Automatic switch onto fault logic, voltage- and current-based function ZCVPSOF is a
complementary function to impedance measuring functions, but may use the information
from such functions.
With ZCVPSOF, a fast trip is achieved for a fault on the whole line when the line is being
energized. The ZCVPSOF tripping is generally non-directional to secure a trip at fault
situations where directional information cannot be established, for example, due to lack of
polarizing voltage when a line potential transformer is used.
Automatic activation based on dead-line detection can only be used when the voltage
transformer is situated on the line side of a circuit breaker.
When line side voltage transformers are used, the use of the nondirectional distance zones
secures switch onto fault tripping for close-in three-phase short circuits. The use of the
nondirectional distance zones also gives a fast fault clearance when energizing a bus from
the line with a short circuit fault on the bus.
Other protection functions like time-delayed phase and zero-sequence overcurrent
function can be connected to ZCVPSOF to increase the dependability in the scheme.
When the voltage transformers are situated on the bus side, the automatic switch onto fault
detection based on dead-line detection is not possible. In such cases the deadline detection
is bypassed using the breaker closing status and the switch onto fault logic is activated.
Section 8 1MRK 506 369-UUS -
Impedance protection
474 Line distance protection REL670 2.2 ANSI
Application manual
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