ABB RELION 670 Series Applications Manual page 176

Section 7
Current protection
well suited to operate in teleprotection communication schemes, which enables fast clearance of
unsymmetrical faults on transmission lines. The directional function uses the voltage polarizing
quantity.
Choice of time characteristics: There are several types of time characteristics available such as
definite time delay and different types of inverse time characteristics. The selectivity between
different overcurrent protections is normally enabled by co-ordination between the operating
time of the different protections. To enable optimal co-ordination all overcurrent relays, to be co-
ordinated against each other, should have the same time characteristic. Therefore a wide range of
standardized inverse time characteristics are available: IEC and ANSI.
Table 30: Inverse time characteristics
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)
There is also a user programmable inverse time characteristic.
Normally it is required that the negative sequence overcurrent function shall reset as fast as
possible when the current level gets lower than the operation level. In some cases some sort of
delayed reset is required. Therefore different kinds of reset characteristics can be used.
For some protection applications there can be a need to change the current pickup level for some
time. Therefore there is a possibility to give a setting of a multiplication factor
negative sequence current pick-up level. This multiplication factor is activated from a binary input
signal MULTPUx to the function.
170
1MRK 505 337-UUS A
MultPUx to the
Application manual