Study of numerical O/C relay

Ia Ib IcPick up value 1.07A 1.06A 1ADrop off value 930mA 960mA 930mA

Millisecond counter

Short time inv STI30XDT 1.878 SStd inv SI30XDT 10.21 Sinverse I30XDT 15.9 SVery inv VI30XDT 14.28 SExtre inv EI30XDT 26.99 SLong time inve LTI30XDT 122.9 Sdefinite DT 399.2 mS

Standard inverse curve operating time (S)

I(A) TMS=1 TMS=0.5

2 1.94 10.26

4 3.96 4.932

6 5.85 3.838

8 7.84 3.259

10 9.93 2.920

12 11.93 2.698

14 14.00 2.532

16 16.00 2.399

18 18.00 2.309

PLOT the operating time vs current variation for both TMS values to get the operating characteristic of the relay.