Schweitzer Engineering Laboratories SEL-387E, Инструкция по эксплуатации

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Date Code 20020129 Differential, Restricted Earth Fault, 3-35
Overcurrent, Voltage, and Frequency Elements
SEL-387E Instruction Manual
Figure 3.15: 50Pn1 Phase Definite-Time O/C Element, Torque Controlled
50Pn2 – Phase Instantaneous Element
Figure 3.16 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 3.16: 50Pn2 Phase Instantaneous O/C Element, Torque Controlled
50Pn3 and 50Pn4 – Phase Instantaneous Element
Figure 3.17 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.