IEC07000004 V1 EN
Figure 108: 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.
1MRK502052-UEN B Section 7
Impedance protection
257
Technical manual
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