ABB RED615 Technical Manual page 290

Section 4
Protection functions
284
coil in compensated networks. As a result the characteristic angle is set
automatically to suit the earthing method used. The RCA_CTL input can be used to
change the operation criteria as described in
Table 289: Relay characteristic angle control in Iosin(φ) and Iocos(φ) operation criteria
Operation mode setting:
Iosin
Iocos
Table 290: Characteristic angle control in phase angle operation mode
Characteristic
RCA_CTL = FALSE
angle setting
-90° φ = -90°
RCA
0° φ = 0°
RCA
Use of the extended phase angle characteristic
The traditional method of adapting the directional earth-fault protection function to
the prevailing neutral earthing conditions is done with the Characteristic angle
setting. In an unearthed network, Characteristic angle is set to -90 degrees and in a
compensated network Characteristic angle is set to 0 degrees. In case the earthing
method of the network is temporarily changed from compensated to unearthed due
to the disconnection of the arc suppression coil, the Characteristic angle setting
should be modified correspondingly. This can be done using the setting groups or
the RCA_CTL input. Alternatively, the operating sector of the directional earth-
fault protection function can be extended to cover the operating sectors of both
neutral earthing principles. Such characteristic is valid for both unearthed and
compensated network and does not require any modification in case the neutral
earthing changes temporarily from the unearthed to compensated network or vice
versa.
The extended phase angle characteristic is created by entering a value of over 90
degrees for the Min forward angle setting; a typical value is 170 degrees (Min
reverse angle in case Directional mode is set to "Reverse"). The Max forward
angle setting should be set to cover the possible measurement inaccuracies of
current and voltage transformers; a typical value is 80 degrees (Max reverse angle
in case Directional mode is set to "Reverse").
Table 289
RCA_CTL = FALSE
Actual operation mode: Iosin
Actual operation mode: Iocos
RCA_CTL = TRUE
φ
RCA
φ
RCA
1YHT530004D05 D
and Table 290.
RCA_CTL = TRUE
Actual operation mode: Iocos
Actual operation mode: Iosin
= 0°
= -90°
615 series
Technical Manual