ABB Relion REC670 Applications Manual page 147

1MRK 511 358-UEN A
SN> is the operate power level for the directional function when OpMode is set 3I03U0Cosfi .
The setting is given in % of
capacitive earth fault residual power at required sensitivity of the protection.
The input transformer for the Sensitive directional residual over current and power protection
function has the same short circuit capacity as the phase current transformers. Hence, there is
no specific requirement for the external CT core, i.e. any CT core can be used.
If the time delay for residual power is chosen the delay time is dependent on two setting
parameters.
multiplier. The time delay will follow the following expression:
=
t
inv
3I 3U cos (measured)
EQUATION1957 V1 EN-US
INDir> is the operate current level for the directional function when OpMode is set 3I0 and fi .
The setting is given in % of
current at required sensitivity of the protection.
OpINNonDir> is set On to activate the non-directional residual current protection.
INNonDir> is the operate current level for the non-directional function. The setting is given in
IBase . This function can be used for detection and clearance of cross-country faults in a
% of
shorter time than for the directional function. The current setting should be larger than the
maximum single-phase residual current on the protected line.
TimeChar is the selection of time delay characteristic for the non-directional residual current
protection. Definite time delay and different types of inverse time characteristics are available:
Table 19:
Curve name
ANSI Extremely Inverse
ANSI Very Inverse
ANSI Normal Inverse
ANSI Moderately Inverse
ANSI/IEEE Definite time
ANSI Long Time Extremely Inverse
ANSI Long Time Very Inverse
ANSI Long Time Inverse
IEC Normal Inverse
IEC Very Inverse
IEC Inverse
IEC Extremely Inverse
IEC Short Time Inverse
IEC Long Time Inverse
IEC Definite Time
User Programmable
ASEA RI
RXIDG (logarithmic)
Application manual
SBase . The setting should be based on calculation of the active or
SRef is the reference residual power, given in % of SBase . kSN is the time
×
kSN Sref
j
× ×
0 0
IBase . The setting should be based on calculation of the earth fault
Inverse time characteristics
Section 7
Current protection
(Equation 59)
141