When the reset period is initiated, the time for which START has been active issaved. If the fault reoccurs, that is, the negative-sequence current rises above theset value during the reset period, the operate calculations are continued using thesaved values. If the reset period elapses without a fault being detected, the operatetimer is reset and the saved values of start time and integration are cleared.

Inv. curve BThe inverse time equation for curve type B is:

t sk

I

I

I

Ir

S

r

[ ] =

2

2 2

GUID-805DCB50-71D2-4721-830B-3343E1A5500B V1 EN (Equation 68)

t[s] Operate time in seconds

k Machine time Mult

I2 Negative-sequence current

IS Set Start value

Ir Set Rated current

1MRS757644 B Section 4Protection functions

620 series 441Technical Manual