Areva MiCOM P441 - P44 X;En AD;E44

Update Documentation P44x/EN AD/E44
MiCOM P441, P442 & P444 Page 23/82
4.7.2 Line in one pole open condition (during single-pole trip)
In this case, the power swing only occurs on two phases. A power swing is detected if:
• At least one phase-phase impedance is within the start-up zone after having crossed
the power swing band in more than 5ms.
NOTA: During an open-pole condition, the P44x monitors the power swing on
the healthy phase-phase loop. No external information is needed if
the voltage transformers are on the line side. If the voltage
transformers are on the bus side, the «pole discrepancy» signal
should be used. The «pole discrepancy» input represents a «one-
circuit-breaker-pole-open» condition.
4.7.4 Tripping logic
Depending on the blocking or unblocking selected, the P44x will trip or block as the swing
(stable or unstable) passes through the zones.
NOTA: If selected, tripping will occur if the impedance stays in any zone
longer than its time delay.(See Chapter AP – section 2.13)
There is a master unblocking timer that is used to override any blocked zone (unblocking
time delay). This is used to separate the sources (open the breaker, 3-phase trip) in the
event that a block was taking place, and the impedance remained in the blocked zone for a
relatively long time. This would be indicative of a serious overcurrent condition as a result of
too great a power transfer after a disturbance (a power swing that does not pass through or
recover). If the impedance point moves out of the start-up characteristic again before the
time delay expires, a trip is not issued and the adjustable time delay is reset.
Unblocking the Zones Blocked due to Faults
In order to protect the network against a fault that may occur during power swing, blocking
signals can be stopped when current thresholds are exceeded. For detecting any type of
fault during a power swing, the P44x uses the adjustable unblocking current
thresholds :
A residual current threshold equal to 0.1 I
n
+ (kr x I
max
(t)).
A negative-sequence current threshold equal to 0.1 I
n
+ (ki x I
max
(t)).
A phase current threshold: I
MAX
.
A Delta phase current criteria can be enabled in S1 (since version C1.0) – to detect the
3phase fault (with faulty current lower than Swing current) during Power swing