tDLD: The time delay for activating ZCVPSOF by the internal dead-line detection is, by
default, set to 0.2 seconds. It is suitable in most applications. The delay shall not be set too
short to avoid unwanted activations during transients in the system.
Mode: The operation of ZCVPSOF has three modes for defining the criteria for tripping.
The setting of Mode is, by default, UILevel, which means that the tripping criterion is
based on the setting of IPh< and UPh<. The choice of UILevel gives a faster and more
sensitive operation of the function, which is important for reducing the stress that might
occur when energizing onto a fault. However, the voltage recovery can be slow in some
systems when energizing the line. Therefore, if the timer tDuration is set too short,
ZCVPSOF can interpret this as a fault and release a trip.
When Mode is set to Impedance, the operate criterion is based on the BC input (breaker
closing), which can be the start of the overreaching zone from the impedance zone
measurement or a tOperate-delayed START_DLYD input. A nondirectional output signal
should be used from an overreaching zone. The selection of the Impedance mode gives
increased security.
When Mode is set to UILvl&Imp, the condition for tripping is an ORed between UILevel
and Impedance.
tDuration: The setting of the timer for the release of UILevel is, by default, 0.02 seconds,
which has proven to be suitable in most cases from field experience. If a shorter time delay
is to be set, it is necessary to consider the voltage recovery time during line energization.
tOperate: The time delay for the START_DLYD input to activate TRIP when Mode is set
to Impedance or UILvl&Imp is, by default, set to 0.03 seconds.
8.19 Phase preference logic PPLPHIZ
8.19.1 Identification
Function description
IEC 61850
identification
IEC 60617
identification
ANSI/IEEE C37.2
device number
Phase preference logic PPLPHIZ - -
8.19.2 Application
Phase preference logic function PPLPHIZ is an auxiliary function to Distance protection
zone, quadrilateral characteristic ZMQPDIS (21) and Phase selection with load
encroachment, quadrilateral characteristic function FDPSPDIS (21). The purpose is to
create the logic in resonance or high resistive grounded systems (normally sub-
Section 8 1MRK 506 369-UUS -
Impedance protection
476 Line distance protection REL670 2.2 ANSI
Application manual
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