4.2.8.2
Function block
67YN
BLOCK
TRIP
VG
IG
RESET
RELEASE
PICKUP
BLK_EF
INTR_EF
PEAK_IND
GUID-A65D073B-32BA-45B6-9881-77C146EA64F6 V1 EN
Figure 210:
Function block
4.2.8.3
Functionality
The multifrequency admittance-based ground-fault protection function 67YN provides
selective directional ground-fault protection for high-impedance grounded networks, that
is, for compensated, ungrounded and high resistance grounded systems. It can be applied
for the ground-fault protection of overhead lines and underground cables.
The operation of 67YN is based on multifrequency neutral admittance measurement,
utilizing cumulative phasor summing technique. This concept provides extremely secure,
dependable and selective ground-fault protection also in cases where the residual
quantities are highly distorted and contain non-fundamental frequency components.
The sensitivity that can be achieved is comparable with traditional fundamental frequency
based methods such as IoCos/IoSin (67/51N, 67/50N), Watt/Varmetric (32N) and neutral
admittance (21YN).
67YN is capable of detecting faults with dominantly fundamental frequency content as
well as transient, intermittent and restriking ground faults. 67YN can be used as an
alternative solution to transient or intermittent function 67NIEF.
67YN supports fault direction indication both in operate and non-operate direction, which
may be utilized during fault location process. The inbuilt transient detector can be used to
identify restriking or intermittent ground faults, and discriminate them from permanent or
continuous ground faults.
The operation characteristic is defined by a tilted operation sector, which is universally
valid for ungrounded and compensated networks.
The operating time characteristic is according to the definite time (DT).
The function contains a blocking functionality to block function outputs, timers or the
function itself.
Section 4
1MAC059074-MB A
Protection functions
438
615 series ANSI
Technical Manual
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