ABB RELION REX640 - Page 1291

-U
0
( polarizing quantity)
I
0
(operating quantity)
RCA = -90 deg
Min reverse angle
Max reverse angle
Min forward
angle
Max forward
angle
Backward
area
Forward
area
Min operate voltage
Min operate current
Non-operating area
Non-operating area
Characteristic
Angle/ Max
Torque line
zero torque line
Figure 733: Configurable directional characteristics (RCA = -90˚) for an isolated
network
Characteristic angle
should be set to a positive value if the operating
signal lags the polarizing quantity -VG or -VN, respectively, and a negative
value if operating signal leads the polarizing quantity, respectively.
Table 1221: Recommended Characteristic angle setting for different network
Type of network Characteristic angle recommended
Compensated network 0°
Solidly grounded network +60°
Isolated network –90°
The Characteristic angle setting is adjusted to the operation according to the
method of neutral-point grounding, so that in an isolated network Characteristic
angle is –90° and in a compensated network 0°. In addition, Characteristic angle can
be changed via the control signal RCA_CTL, in which case the alternatives are –90°
and 0°. The operation of the RCA_CTL input depends on the Characteristic angle
setting.
The Peterson coil or the grounding resistor may be temporarily out of operation. To
keep the protection scheme selective, it is necessary to update the Characteristic
angle settings accordingly. This is done with an auxiliary input in the relay which
receives a signal from an auxiliary switch of the disconnector of the Peterson coil in
compensated networks or of the grounding resistor in grounded network as a result
the Characteristic angle is set automatically to suit the earthing method.
Table 1222: Characteristic angle control for the RCA_CTL condition
Characteristic angle Setting
RCA_CTL=FALSE RCA_CTL=TRUE
–90° Characteristic angle = –90° Characteristic angle = 0°
0° Characteristic angle = 0° Characteristic angle = –90°
1MRS759142 F Protection related functions
REX640
Technical Manual
1291