ABB 615 Series ANSI, Technical Manual

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1MAC050144-MB C
Section 11
General function block features
615 series ANSI 653
Technical Manual
11.2.2 Reset in inverse-time modes
The user can select the reset characteristics by using the Type of reset curve setting as
follows:
Table 541: Values for reset mode
Immediate reset
If the Type of reset curve setting in a drop-off case is selected as "Immediate", the inverse
timer resets immediately.
Definite time reset
The definite type of reset in the inverse-time mode can be achieved by setting the Type of
reset curve parameter to “Def time reset”. As a result, the trip inverse-time counter is
frozen for the time determined with the Reset delay time setting after the current drops
below the set Pickup value , including hysteresis.The integral sum of the inverse-time
counter is reset, if another pickup does not occur during the reset delay.
Inverse reset
Standard delayed inverse reset
The reset characteristic required in ANSI (IEEE) inverse-time modes is provided by
setting the
Type of reset curve parameter to “Inverse reset”. In this mode, the time delay
for reset is given with the following formula using the coefficient D, which has its values
defined in the table below.
(Equation 83)
t[s] Reset time (in seconds)
kset
Time multiplier
I Measured current
I> set
Pickup value
Setting name Possible values
Type of reset curve 1=Immediate
2=Def time reset
3=Inverse reset
If the Type of reset curve setting is selected as “Def time reset”, the current
level has no influence on the reset characteristic.
Inverse reset curves are available only for ANSI and user-programmable
curves. If you use other curve types, immediate reset occurs.
t s
D
I
I
k [ ]
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