REG 316*4 1MRB520049-Uen / Rev. F ABB Switzerland Ltd
3-79
3.5.6. Inverse time overcurrent (Current-Inv)
A. Application
Overcurrent function with time delay inversely proportional to the
current and definite minimum tripping time (IDMT).
B. Features
· operating characteristics (see Fig. 3.5.6.1) according to
British Standard 142:
c = 0.02 : normal inverse
c = 1 : very inverse and long time earth fault
c = 2 : extremely inverse.
· insensitive to DC component
· insensitive to harmonics
· single or three-phase measurement
· detection of the highest phase value in the three-phase mode
· wider setting range than specified in B.S. 142.
C. Inputs and outputs
I. C.t./v.t. inputs:
· current
II. Binary inputs:
· Blocking
III. Binary outputs:
· pick-up
· tripping
IV. Measurements:
· current amplitude.
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