GE P444 User Manual

P
44x/EN AP/Hb6
Application Notes
(AP) 5
-66 MiCOM P40 Agile
P442, P444
After the 500 ms TOR-SOTF time windows has ended, the I>3 overcurrent element remains
in service with a trip time delay equal to the setting ‘Group 1/Back-up I>/I>3 Time Delay’.
This element would trip for close-up high current faults, such as those where maintenance
earth clamps are inadvertently left in position on line energisation.
The ‘I>3 Time Delay’ element can be permanently enabled, or enabled only for SOTF or
TOR (Figure 43). It is also used to detect close-up faults (in SOTF-TOR tripping logic no
time-delay is applied, DDB:'I>3start').
3.2.7.5 Switch on to Fault by Level Detectors
The SOTF level detectors (Bit 6 in the SOTF logic), allows an instantaneous 3-phase trip
from any low set I< level detector (Figure 43), provided that its corresponding Live Line level
detector has not picked up within 20 ms. When closing a circuit breaker to energise a healthy
line, current would normally be detected above setting, but no trip results as the system
voltage rapidly recovers to near nominal. Only when a line fault is present will the voltage fail
to recover, resulting in a trip.
SOTF trip by level detectors per phase: If V
phase
< 70% Vn AND if I
phase
> 5% In for 20 ms (to
avoid any maloperation due to an unstable contact during the reclose command signal), an
instantaneous trip command is issued.
3.2.7.6 Inputs /Outputs in TOR / SOTF Logic
The following DDB are used or available for TOR / SOTF logic (see section P44x/EN PL):
• Inputs:
 Man Close CB,
 AR Reclaim,
 CB aux A,
 CB aux B,
 CB aux C.
• Outputs:
 SOTF Enable,
 TOR Enable,
 TOC Start A,
 TOC Start B,
 TOC Start C,
 Any Pole Dead,
 All Pole Dead,
 SOTF-TOR Trip.
3.2.7.7 Logic Diagram
In the SOTF-TOR logic diagram, the following logic name accronyms are used:
• Ia<, Ib< or Ic<: No current detected (I< threshold, by default 5% In, or I< CB Fail),
• Va>, Vb> or Vc>: Live voltage detected (V Live Line threshold, fixed at 70% Vn),
• Z1, Z1 + Z2, Z1 + Z2 + Z3, Z4, Zp, All Zones: Zones detected (+ = OR),
• 'Dist Trip A', 'B' or 'C' (DDB): Trip (phase A, B or C) by distance logic,
• 'I3> Start' (DDB): Detection by I>3 overcurrents (not filtered by inrush),
• 'TOC Start A', 'B' or 'C' (DDB): Trip On Close on phase A, B or C,
• 'TOR (or SOTF) All Zones': TOR (or SOTF) logic enabled for all zones (distance
start).
Settings are set using ‘Distance schemes / TOR-SOTF Mode’ cell.

GE P444 Specifications

General

Brand	GE
Model	P444
Category	Protection Device
Language	English