GE P444 User Manual

Application Notes
P44x/EN AP/Hb
6
MiCOM P40 Agile P442, P444
(AP) 5-
61
Note: For DEF the logic used will depend upon which settings are enabled:
• Same channel (shared)
In this case, the DEF channel is the Main Distance channel signal (the scheme & contacts of
carrier received will be identical)
• Independent channel (2 Different channels) – (2 independent contacts)
3.2.7 Trip on Reclose (TOR) / Switch On To Fault (SOTF) modes
Switch on to fault protection (SOTF) is provided for high speed clearance of any detected
fault immediately following manual closure of the circuit breaker. SOTF protection remains
enabled for 500ms following circuit breaker closure, detected via the CB Man Close input or
CB close with CB control or Internal detection with all poles dead (see Figure 40), or for the
duration of the close pulse on internal detection.
Instantaneous three pole tripping (and auto-reclose blocking) can also be selected
Trip on reclose protection (TOR) is provided for high speed clearance of any fault detected
immediately following autoreclosure of the circuit breaker.
Instantaneous three pole tripping (TOR logic) can be selected for faults detected by various
elements, (see the settings description above). TOR protection remains enabled for 500ms
following circuit breaker closure. The use of a TOR scheme is usually advantageous for most
distance schemes, since a persistent fault at the remote end of the line can be cleared
instantaneously after reclosure of the breaker, rather than after the zone 2 time delay.
3.2.7.1 Setting Guidelines
• When the overcurrent option is enabled, the I>3 current setting applied should be
above load current, and > 35% of peak magnetising inrush current for any connected
transformers as this element has no second harmonic blocking. Setting guidelines for
the I>3 element are shown in more detail in Table below.
• When a Zone 1 Extension scheme is used along with autoreclosure, it must be
ensured that only Zone 1 distance protection can trip instantaneously for TOR.
Typically, TOR-SOTF Mode bit 0 only would be set to “1”. Also the I>3 element must
be disabled to avoid overreaching trips by level detectors.
3.2.7.2 Initiating TOR-SOTF Protection
SOTF-TOR Activation
The logic (Figure 40) issues 2 signals TOR Enable - SOTF Enable. There is a difference
between these 2 signals as the autorecloser (whether internal or external) which must be
blocked for the SOTF logic.
The detection of an open pole is enabled by the Any Pole Dead signal (at least one pole is
open). It is an OR logic of the internal analogue detection (level detectors) and of the
external detection (given by CB status: 52A/52B, which is required in the case of a VT on the
Bus side).
The V< and I< Dead Pole Level Detectors are settable per phase as described belows:
• V< is either a fixed threshold 20% Vn or equal to the V Dead Line threshold of the
check synchronism function if enabled, (default value for V< dead line = 20% V
N
)
• I< is either a fixed threshold of 5% In or equal to the ‘I< Current Set’ threshold of the
Breaker Failure protection function (default value for I< CB fail = 5% I
N
).

GE P444 Specifications

General

Brand	GE
Model	P444
Category	Protection Device
Language	English