GE P444 User Manual

P
44x/EN AP/Hb6
Application Notes
(AP) 5
-26 MiCOM P40 Agile
P442, P444
Single-phase fault
The reference voltage is stored in memory when the fault appears. When the fault is
eliminated by single-phase tripping, the high-speed single-phase auto-reclose (HSAR) is
started.
If a fault appears less than three cycles after the AR starts, the stored voltage value remains
valid as the reference and is used to calculate direction.
If no fault appears during the three cycles after the AR starts, the reference voltage value
becomes that of one of the healthy phases.
If a fault appears during the continuation of the AR cycle or reclosure occurs, the stored
voltage value remains valid for 10 seconds.
If a stored voltage does not exist (SOTF) when one or more loops are convergent within the
start-up characteristic, the directional is forced forward and the trip is instantaneous (if
“SOTF All Zones” is set or according to the zone location if SOTF Zone 2, etc. is set). If the
settable switch on to fault current threshold I>3 is exceeded on reclosure, the relay
instantaneously trips three-phase (No timer I>3 is applied).
Two-phase or three-phase fault
The reference voltage is stored in memory when the fault appears. When the fault is cleared,
the stored voltage value remains valid for 10 seconds. If reclosure occurs during these 10
seconds, the direction is calculated using the stored voltage value.
If a stored voltage does not exist when one or more loops are convergent within the start-up
characteristic, the forward direction is forced and the trip is instantaneous when protection
starts (SOTF All Zones). If the switch on to fault current threshold I>3 is exceeded on
reclosure, the relay instantaneously trips three-phase (TOR All Zones).
The distance element trips immediately as soon as one or more loops converge in the start-
up characteristic during SOTF (SOTF All Zones).
Other modes can be selected to trip selectively by SOTF or TOR according to the fault
location. There are 15 bits of settings in TOR-SOTF logic.
2.4 Faulted Zone Decision
The Decision of the faulted zone is determined by either the zone "Deltas" or "Conventional"
algorithms.
The zones are defined for a convergence between the Dfault and Rfault limits related to
each zone. So, the solution pair (Rfault, Dfault) is said to be convergent if:
• R
fault
(n-1) < R
fault
(i) and R
fault
(n) < R
fault
(i) and |R
fault
(n-1) – R
fault
(n)| < 10% x R
fault
(i)
• D
fault
(n-1) < D
fault
(i) and D
fault
(n) < D
fault
(i) and |D
fault
(n-1) - D
fault
(n)| < k% x D
fault
(i)
where:
k= 5% for zones Z1 and Z1X
and
10% for other zones Z2, Z3, Zp, Zq and Z4.
i= 1, 1X, 2, p, q, 3 and 4.

GE P444 Specifications

General

Brand	GE
Model	P444
Category	Protection Device
Language	English