ABB REC670 Applications Manual page 174

Section 8
Current protection
168
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
IMinx
IEC10000058 V2 EN-US
Figure 69: Minimum operate current and operate time for inverse time
characteristics
In order to fully comply with the curves definition, the setting parameter txMin
shall be set to the value which is equal to the operate time of the selected IEC
inverse curve for measured current of twenty times the set current pickup value.
Note that the operate time value is dependent on the selected setting value for time
multiplier kx.
INxMult: Multiplier for scaling of the current setting value. If a binary input signal
(ENMULTx) is activated, the current operation level is increased by this setting
constant.
ResetTypeCrvx: The reset of the delay timer can be made in different ways. The
possibilities are described in the technical reference manual.
tResetx: Constant reset time delay in s for step x.
HarmBlockx: This is used to enable block of step x from 2
function.
tPCrvx, tACrvx, tBCrvx, tCCrvx: Parameters for user programmable of inverse
time characteristic curve. The time characteristic equation is according to
equation 38:
1MRK 511 401-UEN A
Current
IEC10000058
nd
harmonic restrain
Bay control REC670 2.2 IEC
Application manual