ABB Relion 670 Series Applications Manual page 155

1MRK 511 401-UEN Rev. K
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 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
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.
Operate time
tx
txMin
IEC10000058 V2 EN-US
Figure 70: Minimum operate current and operate time for inverse time characteristics
In order to fully comply with the curves definition, the setting parameter
the value which is equal to the operate time of the selected IEC inverse curve for measured
Bay control REC670
Application manual
15-60 ms
15-60 ms
20-120 ms
INx>Max and INx>Min , the closest of the limits to INx> is used by the function. If
IMinx
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IMinx is set above INx> for any step,
Current
IEC10000058
Section 8
Current protection
txMin shall be set to
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