3-38
Differential, Restricted Earth Fault,
Date Code 20020129
Overcurrent, Voltage, and Frequency Elements
SEL-387E Instruction Manual
50Qn2 and 50Nn2 – Sequence Instantaneous Element Logic
Figure 3.20 shows the logic for the instantaneous 50Qn2 negative-sequence element and the
instantaneous 50Nn2 residual element
Figure 3.20: 50Qn2 and 50Nn2 Sequence Instantaneous O/C Element, Torque Controlled
50Qn2 Negative-Sequence Instantaneous Element
The 50Qn2 element compares the magnitude of the calculated negative-sequence current, 3I2Wn,
to the pickup setting, 50Qn2P. If the calculated negative-sequence current exceeds the pickup
level, a logical 1 asserts at one input to the AND gate. The torque-control SEL
OGIC
control
equation, 50Qn2TC, determines the other AND input. If 50Qn2TC is true, Relay Word bit
50Qn2 asserts.
50Nn2 Residual Instantaneous Element
The 50Nn2 element compares the magnitude of the calculated residual current, IRWn, to the
pickup setting, 50Nn2P. If the calculated residual current exceeds the pickup level, a logical 1
asserts at one input to the AND gate. The torque-control SEL
OGIC
control equation, 50Nn2TC,
determines the other AND input. If 50Nn2TC is true, Relay Word bit 50Nn2 asserts.
51Qn and 51Nn – Sequence Inverse-Time Elements
Figure 3.21 shows the logic for the inverse-time 51Qn negative-sequence element and the
instantaneous 51Nn residual element.
Figure 3.21: 51Qn and 51Nn Sequence Inverse-Time O/C Element, Torque Controlled
Содержание SEL-387E
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