ABB Relion 670 series, Technical Reference Manual

Page: 369 / 1232

• the minimum current exceeds 0.10 I
N
(I
N
is IBase parameter set under general
setting).
• the maximum voltage falls below 0.92 VBase
• the voltage Ucosφ (the voltage in phase with the generator current) has an angular
velocity of 0.2...8 Hz and
• the corresponding direction is not blocked.
en07000004.vsd
IEC07000004 V1 EN
Figure 193: 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).
1MRK505222-UUS C
Section 6
Impedance protection
363
Technical reference manual