Schweitzer Engineering SEL-351P - Phase-To-Phase Instantaneous Overcurrent Elements

Date Code 990430 Overcurrent, Voltage, Synchronism Check, and Frequency Elements 3-7
SEL-351P Manual Técnico
relays). These times do not include output contact operating time and, thus, are accurate for
determining element operation time for use in internal SEL
OGIC Control Equations. Output
contact pickup/dropout time is 4 ms (0.25 cycle for a 60 Hz relay; 0.20 cycle for a 50 Hz relay).
If instantaneous overcurrent elements are made directional, the pickup time curve in
Figure SECTION 3: .5 is adjusted as follows:
multiples of pickup setting ≤ 4: add 0.25 cycle
multiples of pickup setting > 4: add 0.50 cycle
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.22345678910
Applied Current (Multiples of Pickup Setting)
Pickup Time (Cycles)
Maximum
Minimum
Figure SECTION 3: .5: SEL-351P Recloser Control Nondirectional Instantaneous
Overcurrent Element Pickup Time Curve
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.22345678910
A
pp
lied Current
(
Multi
p
les of Picku
p
Settin
g)
Reset Time (Cycles)
Maximum
Minimum
Figure SECTION 3: .6: SEL-351P Recloser Control Nondirectional Instantaneous
Overcurrent Element Reset Time Curve
Phase-to-Phase Instantaneous Overcurrent Elements
Four levels of phase-to-phase instantaneous overcurrent elements are available. The different
levels are enabled with the E50P enable setting, as shown in
Figure SECTION 3: .7.