Curve name
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
operating level for some time. Therefore there is a possibility to give a setting of a
multiplication factor IxMult to the negative sequence current pick-up level. This
multiplication factor is activated from a binary input signal ENMULTx to the
function.
9.5.3 Setting guidelines
GUID-460D6C58-598C-421E-AA9E-FD240210A6CC v3
The parameters for Four step negative sequence overcurrent protection NS4PTOC
are set via the local HMI or Protection and Control Manager (PCM600).
The following settings can be done for the four step negative sequence overcurrent
protection:
Operation: Sets the protection to On or Off.
Common base IED values for the primary current (IBase), primary voltage (UBase)
and primary power (SBase) are set in global base values for settings function
GBASVAL.
GlobalBaseSel: Selects the global base value group used by the function to define
IBase, UBase and SBase as applicable.
GUID-F7AA2194-4D1C-4475-8853-C7D064912614 v4
When inverse time overcurrent characteristic is selected, the
operate time of the stage will be the sum of the inverse time delay
Section 9 1MRK 506 369-UEN B
Current protection
490 Line distance protection REL670 2.2 IEC
Application manual
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