Directional Overcurrent Characteristics - ABB RELION REX640 Technical Manual

Section 4
Protection functions
4.4.2.6
744
Blocking logic
There are three operation modes in the blocking function. The operation modes are
controlled by the BLOCK input and the global setting in Configuration/System/
Blocking mode which selects the blocking mode. The BLOCK input can be controlled
by a binary input, a horizontal communication input or an internal signal of the
protection relay's program. The influence of the BLOCK signal activation is
preselected with the global setting Blocking mode.
The Blocking mode setting has three blocking methods. In the "Freeze timers" mode,
the operation timer is frozen to the prevailing value, but the OPERATE output is not
deactivated when blocking is activated. In the "Block all" mode, the whole function
is blocked and the timers are reset. In the "Block OPERATE output" mode, the
function operates normally but the OPERATE output is not activated.

Directional overcurrent characteristics

The forward and reverse sectors are defined separately. The forward operation area is
limited with the Min forward angle and Max forward angle settings. The reverse
operation area is limited with the Min reverse angle and Max reverse angle settings.
The sector limits are always given as positive degree values.
In the forward operation area, the Max forward angle setting gives the
counterclockwise sector and the Min forward angle setting gives the corresponding
clockwise sector, measured from the Characteristic angle setting.
In the backward operation area, the Max reverse angle setting gives the
counterclockwise sector and the Min reverse angle setting gives the corresponding
clockwise sector, a measurement from the Characteristic angle setting that has been
rotated 180 degrees.
Relay characteristic angle (RCA) is set positive if the operating current lags the
polarizing quantity, and negative if the operating current leads the polarizing quantity.
1MRS759142 C
REX640
Technical Manual