Curve name
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
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 primary current (IBase), primary voltage (UBase) and
primary power (SBase) are set in Global base values for settings function GBASVAL.
GlobalBaseSel: It is used to select a GBASVAL function for reference of base values.
When inverse time overcurrent characteristic is selected, the operate
time of the stage will be the sum of the inverse time delay and the set
definite time delay. Thus, if only the inverse time delay is required, it
is important to set the definite time delay for that stage to zero.
Section 9 1MRK 502 071-UEN -
Current protection
352 Generator protection REG670 2.2 IEC and Injection equipment REX060, REX061, REX062
Application manual
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