ABB REB670 Series Applications Manual page 174

Section 7
Current protection
Curve name
IEC Normal Inverse
IEC Very Inverse
IEC Inverse
IEC Extremely Inverse
IEC Short Time Inverse
IEC Long Time Inverse
IEC Definite Time
User Programmable
ASEA RI
RXIDG (logarithmic)
The different characteristics are described in the Technical Reference Manual (TRM).
Ix> : Operation negative sequence current level for step x given in % of IBase .
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.
kx : Time multiplier for the dependent (inverse) characteristic.
IMinx : Minimum operate current for step x in % of IBase . Set IMinx below Ix> for every step to
achieve ANSI reset characteristic according to standard. If
the ANSI reset works as if current is zero when current drops below
IxMult : Multiplier for scaling of the current setting value. If a binary input signal (ENMULTx) is
activated the current operation level is multiplied by this setting constant.
txMin : Minimum operation 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 97: Minimum operate current and operation time for inverse time characteristics
ResetTypeCrvx : The reset of the delay timer can be made in different ways. By choosing
setting there are the following possibilities:
168
IMinx
IMinx is set above Ix> for any step
IMinx .
Current
IEC10000058
1MRK 505 370-UEN D
Busbar protection REB670
Application manual