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Date Code 20011112
Line Current Differential, Distance, Out-of-Step, Overcurrent,
3-63
Voltage, Synchronism Check, and Frequency Elements
SEL-311L Instruction Manual
Table 3.8: Phase Time-Overcurrent Element (Maximum Phase) Logic Outputs
Relay Word Bit
Definition/ Indication
Application
51P
Maximum phase current, I
ABC
, is
greater than phase time-
overcurrent element pickup
setting 51PP.
Element pickup testing or other
control
applications. See
Trip
Logic
in
Section 5: Trip and
Target Logic
.
51PT
Phase time-overcurrent element is
timed out on its curve.
Tripping and other control
applications. See
Trip Logic
in
Section 5: Trip and Target Logic
.
51PR
Phase time-overcurrent element is
fully reset.
Element reset testing or other
control applications.
51PT Element Torque Control Switch Operation
Torque Control Switch Closed
The pickup comparator in Figure 3.47 compares the pickup setting (51PP) to the maximum phase
current, I
ABC
, if the Torque Control Switch is closed. I
ABC
is also routed to the curve timing/reset
timing functions. The Relay Word Bit logic outputs operate as follows with the Torque Control
Switch closed:
51P
= 1 (logical 1), if I
ABC
> pickup setting 51PP and the phase time-overcurrent element
is timing or is timed out on its curve
= 0 (logical 0), if I
ABC
≤
pickup setting 51PP
51PT = 1 (logical 1), if I
ABC
> pickup setting 51PP and the phase time-overcurrent element
is timed out on its curve
= 0 (logical 0), if I
ABC
> pickup setting 51PP and the phase time-overcurrent element
is timing, but not yet timed out on its curve
= 0 (logical 0), if I
ABC
≤
pickup setting 51PP
51PR = 1 (logical 1), if I
ABC
≤
pickup setting 51PP and the phase time-overcurrent element
is fully reset
= 0 (logical 0), if I
ABC
≤
pickup setting 51PP and the phase time-overcurrent element
is timing to reset (not yet fully reset)
= 0 (logical 0), if I
ABC
> pickup setting 51PP and the phase time-overcurrent element
is timing or is timed out on its curve
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