Schweitzer Engineering Laboratories SEL-387E - 51 PC1 and 51 NC1 Element Logic

Date Code 20080110 Protection Functions 3-41
SEL-387E Instruction Manual
DWG: M387E069
1200 A
CT3
SEL-387E
CB3
W1
3800 A
CT Equivalent 1 and 2
W3
W1 and W2
Combination:Windings 1 and 2
3800 A
1200 A
500 A 700 A
CT1 CT2CB1 CB2
W2
W3
Figure 3.22: Combined Overcurrent Example
51PC1 and 51NC1 Element Logic
The logic for the inverse-time combined overcurrent elements 51PC1 and 51NC1 is shown in
Figure 3.23.