Schweitzer Engineering SEL-351P - Reset Timing Details (51 P1 T Element Example); Setting 51 P1 RS = N; Setting 51 P1 RS = y; Neutral Ground Time-Overcurrent Elements

3-22 Overcurrent, Voltage, Synchronism Check, and Frequency Elements Date Code 990430
SEL-351P Manual Técnico
Reset Timing Details (51P1T element example)
Refer to
Figure SECTION 3: .14.
Any time current I
P
goes above pickup setting 51P1P and the phase time-overcurrent element
starts timing, Relay Word bit 51P1R (reset indication) = logical 0. If the phase time-overcurrent
element times out on its curve, Relay Word bit 51P1T (curve time-out indication) = logical 1.
Setting 51P1RS = Y
If electromechanical reset timing setting 51P1RS = Y, the phase time-overcurrent element reset
timing emulates electromechanical reset timing. If maximum phase current, I
P
, goes above
pickup setting 51P1P (element is timing or already timed out) and then current I
P
goes below
51P1P, the element starts to time to reset, emulating electromechanical reset timing. Relay Word
bit 51P1R (resetting indication) = logical 1 when the element is fully reset.
Setting 51P1RS = N
If reset timing setting 51P1RS = N, element 51P1T reset timing is a 1-cycle dropout. If current I
P
goes above pickup setting 51P1P (element is timing or already timed out) and then current I
P
goes below pickup setting 51P1P, there is a 1-cycle delay before the element fully resets. Relay
word bit 51P1R (reset indication) = logical 1 when the element is fully reset.
Neutral Ground Time-Overcurrent Elements
Figure SECTION 3: .16: Neutral Ground Time-Overcurrent Element 51N1T (with
Directional Control Option)