Schweitzer Engineering SEL-387-0 - Figure 3.18 50 Pn1 Phase Definite-Time O;C Element, Torque Controlled; Figure 3.19 50 Pn2 Phase Instantaneous O;C Element, Torque Controlled; Figure 3.20 50 Pn3 and 50 Pn4 Phase Instantaneous O;C Element, Nontorque Controlled

3.50
SEL-387-0, -5, -6 Relay Instruction Manual Date Code 20170601
Differential, Restricted Earth Fault, Thermal, and Overcurrent Elements
Overcurrent Element
Figure 3.18 50Pn1 Phase Definite-Time O/C Element, Torque Controlled
50Pn2–Phase Instantaneous Element
Figure 3.19 shows the logic for the 50Pn2 element. The 50Pn2 element logic
compares magnitudes of phase input currents IAWn, IBWn, and ICWn to
pickup setting 50Pn2P. If one or more current magnitudes exceed the pickup
level, a logic 1 asserts at one input to the AND gate. The torque-control
SEL
OGIC control equation 50Pn2TC determines the other AND input. If
50Pn2TC is true, Relay Word bit 50Pn2 asserts.
Figure 3.19 50Pn2 Phase Instantaneous O/C Element, Torque Controlled
50Pn3 and 50Pn4–Phase Instantaneous Element
Figure 3.20 shows the logic for the two nontorque-controlled phase
instantaneous elements. The two elements find application primarily in level
detection or phase identification. The logic compares magnitudes of phase
input currents IAWn, IBWn, and ICWn to pickup setting 50Pn3P(4P). Any
phase current exceeding the pickup level will assert the appropriate phase-
specific Relay Word bit, 50An3(4), 50Bn3(4), or 50Cn3(4). These bits enter
an OR gate to assert Relay Word bit 50Pn3(4), indicating “any phase” pickup.
Figure 3.20 50Pn3 and 50Pn4 Phase Instantaneous O/C Element,
Nontorque Controlled
+
–
D
0
50Pn1T
–
+
+
–
50Pn1
D = 50Pn1D
(n = Winding 1, 2, 3, or 4)
|IAWn|
|IBWn|
|ICWn|
50Pn1P
Relay
Word
Bit
Relay
Word
Bit
50Pn1TC (SELOGIC
control equation TRUE)
+
–
–
+
+
–
50Pn2
(n = Winding 1, 2, 3, or 4)
|IAWn|
|IBWn|
|ICWn|
50Pn2P
Relay
Word
Bit
50Pn2TC (SELOGIC
control equation TRUE)
+
–
–
+
+
–
50Pn3(4)
(n = Winding 1, 2, 3, or 4)
|IAWn|
|IBWn|
|ICWn|
50Pn3P
(4P)
50An3(4)
50Bn3(4)
50Cn3(4)
Relay
Word
Bits
Relay
Word
Bits