
3-6
Overcurrent, Voltage, Synchronism Check, and Frequency Elements
Date Code 20020215
SEL-351R Instruction Manual
67P1TC = IN105 Input IN105 deasserted (67P1TC = IN105 = logical 0):
Then phase instantaneous/definite-time overcurrent elements 67P1/67P1T
are defeated and nonoperational, regardless of any other setting.
Input IN105 asserted (67P1TC = IN105 = logical 1):
Then only the corresponding directional control input from Figure 4.21
has to be considered in the control of phase instantaneous/definite-time
overcurrent elements 67P1/67P1T.
If directional control enable setting E32 =N, then phase
instantaneous/definite-time overcurrent elements 67P1/67P1T are enabled
and nondirectional.
Sometimes SEL
OGIC
control equation torque control settings are set to provide directional
control. See
Directional Control Provided by Torque Control Settings
at the end of
Section 4:
Loss-of-Potential, Load Encroachment, and Directional Element Logic
.
Combined Single-Phase Instantaneous Overcurrent Elements
The single-phase instantaneous overcurrent element Relay Word bit outputs in Figure 3.1 are
combined together in Figure 3.4 on a per phase basis, producing Relay Word bit outputs 50A,
50B, and 50C.
Relay Word bits 50A, 50B, and 50C can be used to indicate the presence or absence of current in
a particular phase.
Figure 3.4: Combined Single-Phase Instantaneous Overcurrent Elements
Pickup and Reset Time Curves
Figure 3.5 and Figure 3.6 show pickup and reset time curves applicable to all nondirectional
instantaneous overcurrent elements in the SEL-351R (60 Hz or 50 Hz 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).
Содержание SEL-351R
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