IEC07000004 V1 EN-US
Figure 197: Different generator quantities as function of the angle between the equivalent
generators
An alarm is given when movement of the rotor is detected and the rotor angle exceeds the angle
set for 'WarnAngle'.
Slipping is detected when:
• a change of rotor angle of min. 50 ms is recognized
• the slip line is crossed between Z
A
and Z
B
.
When the impedance crosses the slip line between Z
B
and Z
C
it counts as being in zone 1 and
between Z
C
and Z
A
in zone 2. The entire distance ZA-ZB becomes zone 1 when signal EXTZONE1 is
high (external device detects the direction of the centre of slipping).
After the first slip, the signals ZONE1 or ZONE2 and – depending on the direction of slip - either
GEN or MOTOR are issued.
Every time pole slipping is detected, the impedance of the point where the slip line is crossed and
the instantaneous slip frequency are displayed as measurements.
Further slips are only detected, if they are in the same direction and if the rate of rotor movement
has reduced in relation to the preceding slip or the slip line is crossed in the opposite direction
outside ZA-ZB. A further slip in the opposite direction within Z
A
-Z
B
resets all the signals and is
then signalled itself as a first slip.
The TRIP1 tripping command and signal are generated after N1 slips in zone 1, providing the rotor
angle is less than
TripAngle
. The TRIP2 signal is generated after N2 slips in zone 2, providing the
rotor angle is less than
TripAngle
.
1MRK 502 066-UUS B Section 7
Impedance protection
373
Technical manual
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