ABB RELION 620 Series Technical Manual page 347

1MAC504801-IB E
620 series ANSI
Technical Manual
The sector limits are always given as positive degree values.
The Characteristic angle setting is also known as Relay Characteristic
Angle (RCA), Relay Base Angle or Maximum Torque Line.
Min reverse
angle
Min trip voltage
Max reverse
angle
Min trip current
GUID-BF8D237B-BD76-45B1-935D-6913F4C188B3-ANSI V1 EN
Figure 153: Configurable directional settings
Low-level blocking
For a reliable operation, signal levels should be greater than the minimum level. If they are
not greater than the minimum level, Timer is blocked. If the amplitude of the positive-
sequence current is greater than the Min trip current value and the positive-sequence
voltage amplitude is greater than the Min trip voltage value, the Enable signal is sent to
Timer.
Timer
Once activated, the internal operating timer is started. The Timer characteristic is
according to definite time DT. When Timer has reached the value of Release delay time,
the RELEASE output is activated. If a drop-off situation happens, that is, if the operating
current moves outside the operating sector or signal amplitudes drop below the minimum
level before Release delay time is exceeded, the Timer reset state is activated. If the drop-
off continues for more than Reset delay time, Timer is deactivated.
1
RCA=+45 deg
Max forward
angle
1
Min forward
angle
Section 4
Protection functions
341