ABB REQ650 Applications Manual page 101

1MRK 505 383-UEN A
Breaker protection REQ650 2.2 IEC
Application manual
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 Dt 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:
Protection resetting time:
Breaker opening time:
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.
IMinx: Minimum operate current for step x in % of IB. Set IMinx below INx> for
every step to achieve ANSI reset characteristic according to standard. If IMinx is
set above INx> for any step, signal will reset at current equals to zero.
txMin: Minimum operating time for inverse time characteristics. At high currents,
the inverse time characteristic might give a very short operation time. By setting
this parameter, the operation time of the step can never be shorter than the setting.
Current protection
15-60 ms
15-60 ms
20-120 ms
Section 6
95