Tor-Sotf Trip Logic - GE MiCOM P40 Agile Technical Manual

P44x/EN AP/Hb6
(AP) 5-64
3.2.7.3

TOR-SOTF Trip Logic

During the TOR-SOTF 500 ms window, individual distance protection zones can be enabled
or disabled using the TOR-SOTF Mode ('Distance schemes' menu) function links (TOR
logic Bit0 to Bit4 & SOTF logic Bit5 to Bit0E, see Figure 43 for SOTF-TOR trip logic). Setting
the relevant Bit to 1 will enable that zone, setting Bits to 0 will disable distance zones. When
enabled (Bit = 1), the zones will trip without waiting for their usual time delays. Therefore
tripping can even occur for close-up three phase short circuits where line connected VTs are
used, and memory voltage for a directional decision is unavailable. Setting "All Zones
Enabled" allows instantaneous tripping to occur for all faults within the trip characteristic
shown in Figure 41 below. Note, the TOR-SOTF element has second harmonic current
detection, to avoid maloperation where power transformers are connected in-zone, and
inrush current would otherwise cause problems. Harmonic blocking of distance zones occurs
when the magnitude of the second harmonic current exceeds 25% of the fundamental.
Figure 41: "All Zones" distance characteristic available for SOTF-TOR tripping
Test results from different settings (see P44x/EN ST, 'Distance schemes / TOR-SOTF
Mode').
WARNING:
In the following trip logic results, the following acronyms are used:
Type of Fault
selected Logic
TOR-SOTF
Name of the selection
and setting
The fault is maintained with a duration higher than the 500 ms SOTF time, until a trip occurs.
Zone 3
Settings are not dynamically modified: one setting could affect another
one.
Fault in Zone X
SOTF trip / TOR trip / Dist trip
T0, T1, T2, Tzp (Tzq), T3, T4
– SOTF trip (trip by SOTF (manual reclose)) / TOR trip (autoreclose):
An instantaneous 3-pole trip will occur for a fault in a zone without waiting
for the distance timer to expire
– Dist. Trip: trip by distance protection logic
– T0 (instantaneous trip) and T1, T2, Tzp (Tzq), T3, T4 (Distance
time-delays, for a zone.
MiCOM P40 Agile P442, P444
X
Zone 4
R
Directional
line (not used)
P0535EN
Application Notes