11.2.3 Reset in inverse-time modes
The user can select the reset characteristics by using the
Type of reset curve
setting.
Table 728: Values for reset mode
Setting name Possible values
Type of reset curve
1=Immediate
2=Def time reset
3=Inverse reset
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 operate
inverse-time counter is frozen for the time determined with the
Reset delay time
setting after the current drops below the set
Start value
, including hysteresis. The
integral sum of the inverse-time counter is reset, if another start does not occur
during the reset delay.
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
Inverse reset curves are available only for ANSI and user-programmable
curves. If you use other curve types, immediate reset occurs.
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.
t s
D
I
I
k[ ] =
>
−
⋅
2
1
(Equation 82)
t[s]
Reset time (in seconds)
k set
Time multiplier
Table continues on the next page
General function block features 1MRS758755 C
806 REC615 & RER615
Technical Manual
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