ABB Relion 670 series, Applications Manual

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to the residual current pick-up level. This multiplication factor is activated from a binary input
signal ENMULTx to the function.
Power transformers can have a large inrush current, when being energized. This inrush current
can have residual current components. The phenomenon is due to saturation of the
transformer magnetic core during parts of the cycle. There is a risk that inrush current will give
a residual current that reaches level above the operating current of the residual overcurrent
protection. The inrush current has a large second harmonic content. This can be used to avoid
unwanted operation of the protection. Therefore, EF4PTOC has a possibility of second
harmonic restrain
2ndHarmStab if the level of this harmonic current reaches a value above a
set percentage of the fundamental current.
8.4.3 Setting guidelines
IP14988-1 v1
M15282-3 v12
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.
The parameters for the four step residual overcurrent protection are set via the local HMI or
PCM600. The following settings can be done for the function.
GlobalBaseSel: Selects the global base value group used by the function to define (IBase),
(
UBase) and (SBase).
SeqTypeUPol: This is used to select the type of voltage polarising quantity i.e. Zero seq or Neg
seq for direction detection.
SeqTypeIPol: This is used to select the type of current polarising quantity i.e. Zero seq or Neg
seq for direction detection.
SeqTypeIDir: This is used to select the type of operating current quantity i.e. Zero seq or Neg
seq for direction detection.
8.4.3.1 Settings for each step (x = 1, 2, 3 and 4)
M15282-9 v12.1.1
Operation: Sets the protection to On or Off.
DirModex: The directional mode of step x. Possible settings are Off/Non-directional/Forward/
Reverse.
Characteristx: Selection of time characteristic for step x. Definite time delay and different
types of inverse time characteristics are available.
Inverse time characteristic enables fast fault clearance of high current faults at the same time
as selectivity to other inverse time phase overcurrent protections can be assured. This is
mainly used in radial fed networks but can also be used in meshed networks. In meshed
networks, the settings must be based on network fault calculations.
To assure selectivity between different protections, in the radial network, there has to be a
minimum time difference D t between the time delays of two protections. To determine the
shortest possible time difference, the operation time of protections, breaker opening time
and protection resetting time must be known. These time delays can vary significantly
between different protective equipment. The following time delays can be estimated:
1MRK 505 343-UEN B Section 8
Current protection
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Application manual