ABB Relion 670 series - Setting Example for Line Application

The ImpedanceZB is the reverse impedance as show in figure 234. ZB should be equal to
the generator transient reactance X'd. The impedance is given in % of the base impedance,
see equation 425.
The ImpedanceZC is the forward impedance giving the borderline between zone 1 and
zone 2. ZC should be equal to the transformer reactance ZT. The impedance is given in %
of the base impedance, see equation
425.
The angle of the impedance line ZB – ZA is given as AnglePhi in degrees. This angle is
normally close to 90°.
StartAngle: An alarm is given when movement of the rotor is detected and the rotor angle
exceeds the angle set for StartAngle. The default value 110° is recommended. It should be
checked so that the points in the impedance plane, corresponding to the chosen StartAngle
does not interfere with apparent impedance at maximum generator load.
TripAngle: If a pole slip has been detected: change of rotor angle corresponding to slip
frequency 0.2 – 8 Hz, the slip line ZA – ZB is crossed and the direction of rotation is the
same as at start, a trip is given when the rotor angle gets below the set TripAngle. The
default value 90° is recommended.
N1Limit: The setting N1Limit gives the number of pole slips that should occur before trip,
if the crossing of the slip line ZA – ZB is within zone 1, that is, the node of the pole slip
is within the generator transformer block. The default value 1 is recommended to
minimize the stress on the generator and turbine at out of step conditions.
N2Limit: The setting N2Limit gives the number of pole slips that should occur before trip,
if the crossing of the slip line ZA – ZB is within zone 2, that is, the node of the pole slip
is in the external network. The default value 3 is recommended give external protections
possibility to split the network and thus limit the system consequencies.
ResetTime: The setting ResetTime gives the time for (PSPPPAM ,78) function to reset
after start when no pole slip been detected. The default value 5s is recommended.
8.16.3.1 Setting example for line application
In case of out of step conditions this shall be detected and the line between substation 1 and
2 shall be tripped.
1MRK 506 369-UUS - Section 8
Impedance protection
Line distance protection REL670 2.2 ANSI 457
Application manual