Areva MiCOM P441, Technical Manual

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P44x/EN AP/E33 Application Notes
Page 110/220 MiCOM P441/P442 & P444
Therefore set Line Impedance and Line Angle: = 5.81 / 80
° Ω
(secondary).
No residual compensation needs to be set for the fault locator, as the relay automatically
uses the kZ0 factor applicable to the distance zone which tripped.
Should a CT residual input be available for the parallel line, mutual compensation could be
set as follows:
kZm Mutual Comp,

kZm

= ZM
0
/ 3.Z
1
Ie: As a ratio.
kZm Angle,
∠
kZm =
∠
ZM
0
/ 3.Z
1
Set in degrees.
The CT ratio for the mutual compensation may be different from the Line CT ratio. However,
for this example we will assume that they are identical.
kZm = ZM
0
/ 3.Z
1
= 0.581 / 79.4
°
/ (3 x 0.484 / 79.4
°
)
= 0.40 / 0
°
Therefore set kZm Mutual Comp = 0.40
kZm Angle = 0
°
4.2
Voltage transformer supervision (VTS) –
Main VT for minZ measurement
4.2.1 VTS logic description
The voltage transformer supervision (VTS) feature is used to detect failure of the analog ac
voltage inputs to the relay. This may be caused by internal voltage transformer faults,
overloading, or faults on the interconnecting wiring to relays. This usually results in one or
more VT fuses blowing. Following a failure of the ac voltage input there would be a
misrepresentation of the phase voltages on the power system, as measured by the relay,
which may result in maloperation of the distance element.
The VTS logic in the relay is designed to detect the voltage failure (with internal thresholds or
external opto input), and automatically adjust the configuration of protection elements
(Distance element is blocked but may be unblocked on I1,I2 or I0 conditions in case of fault
during VTS conditions) whose stability would otherwise be compromised (Distance, DEF,
Weak infeed, Directionnal phase current& all directional elements used in the internal logic).
A settable time-delayed alarm output is also available (min1sec to Max 20sec).
The condition of this alarm is given by:
FFUS_Confirmed = (Fuse_Failure And VTS Timer) Or INP_FFUS_Line
P0530ENa
VN >F.Failure
&
≥
1
I2 >F.Failure
I0 >F.Failure
I >F.Failure
V<F.Failure
∆
I>F.Failure
&
S
Q
R
INP_F.Failure_Line
≥
1
Fuse_Failure
FFUS_Confirmed
VTS Time
delay
S
Q
R
≥
1
Healthy network
All Pole Dead
Any_pole_dead
FIGURE 66 - VTS LOGIC
(S
EE ALSO
DDB
DESCRIPTION IN THE END OF THAT SECTION
)