Hitachi Relion 670 Series Applications Manual page 161

1MRK506375-UEN Rev. N
Table 21:
Curve name
IEC Normal Inverse
IEC Very Inverse
IEC Extremely Inverse
IEC Definite Time
ASEA RI
Normally it is required that EF2PTOC shall reset as fast as possible when the current level gets lower
than the operation level.
8.4.4 Setting guidelines
The parameters for the two step residual over-current protection, zero sequence direction EF2PTOC
is set via the local HMI or PCM600.
The following settings can be done for the two step residual over-current protection.
GlobalBaseSel: Selects the global base value group used by the function to define IBase, UBase and
SBase. Note that this function will only use IBase and UBase values.
Operation: Sets the protection to On or Off.
8.4.4.1 Settings for each step (x = 1 and 2)
DirModex: The directional mode of step x. Possible settings are Off/Non-directional Forward/
Reverse.
t1: Definite time delay for step 1. The definite time t1 is added to the inverse time when inverse time
characteristic is selected. Note that the value set is the time between activation of the start and the
trip outputs.
tDef2: Definite time delay for step 2.
Characterist1: Selection of time characteristic for step 1. 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 have to be a minimum
time difference Dt between the time delays of two protections. The minimum time difference can be
determined for different cases. 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:
Railway application RER670
Application manual
Time characteristics
When inverse time overcurrent characteristic is selected, the operate time of the step 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 step to
zero.
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Section 8
Current protection
IP14988-1 v1
M15282-3 v14
GUID-4F46ED5A-9F8C-451B-AA60-ED570822D5BC v4
155