ABB ret650, Applications Manual

Page: 133 / 392

7.4.3.5 Settings for each step (x = 1, 2, 3 and 4)
M15282-9 v12
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:
Protection operate time: 15-60 ms
Protection resetting time: 15-60 ms
Breaker opening time: 20-120 ms
The different characteristics are described in the technical reference manual.
tx : Definite time delay for step x . The definite time tx 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.
INx> : Operate residual current level for step x given in % of IB .
INx>Max and INx>Min should only be changed if remote setting of operation
current level, INx> , is used. The limits are used for decreasing the used range of
the INx> setting. If INx> is set outside INx>Max and INx>Min , the closest of the
limits to INx> is used by the function. If INx>Max is smaller than INx>Min , the
limits are swapped.
kx : Time multiplier for the dependent (inverse) characteristic for step x .
: Minimum operate current for step in % of IB . Set below INx> for every step to
achieve ANSI reset characteristic according to standard. If is set above INx> for
any step, signal will reset at current equals to zero.
1MRK 504 169-UEN A
Section 7
Current protection
Transformer protection RET650 2.2 IEC 127
Application manual