Schweitzer Engineering SEL-351P - Accuracy; Logic Outputs (51 P1 T Element Example); Torque Control Switch Closed; Torque Control Switch Operation (51 P1 T Element Example)

Date Code 990430 Overcurrent, Voltage, Synchronism Check, and Frequency Elements 3-19
SEL-351P Manual Técnico
Accuracy
Pickup: ±0.01 A secondary and ±3% of setting (1 A nominal phase current inputs, IA, IB, IC)
Curve Timing: ±1.50 cycles and ±4% of curve time for currents between (and including)
2 and 30 multiples of pickup
Logic Outputs (51P1T element example)
The resultant logic outputs in
Figure SECTION 3: .14 are the following Relay Word bits:
Table SECTION 3: .3: Phase Time-Overcurrent Element (maximum phase) Logic
Outputs
Relay Word Bit Definition/ Indication Application
51P1 Maximum phase current, I
P
, is
greater than phase time-
overcurrent element pickup
setting 51P1P.
Element pickup testing or other
control
applications. See Trip
Logic in Section 5: Trip and
Target Logic.
51P1T 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.
51P1R Phase time-overcurrent element is
fully reset.
Element reset testing or other
control applications.
Torque Control Switch Operation (51P1T element example)
Torque Control Switch Closed
The pickup comparator in
Figure SECTION 3: .14 compares the pickup setting (51P1P) to the
maximum phase current, I
P
, if the Torque Control Switch is closed. I
P
is also routed to the curve
timing/reset timing functions. The Relay Word Bits logic outputs operate as follows with the
Torque Control Switch closed:
51P1 = 1 (logical 1), if I
P
> pickup setting 51P1P and the phase time-overcurrent element
is timing or is timed out on its curve
= 0 (logical 0), if I
P
≤ pickup setting 51P1P
51P1T = 1 (logical 1), if I
P
> pickup setting 51P1P and the phase time-overcurrent element
is timed out on its curve
= 0 (logical 0), if I
P
> pickup setting 51P1P and the phase time-overcurrent element
is timing, but not yet timed out on its curve
= 0 (logical 0), if I
P
≤ pickup setting 51P1P
51P1R = 1 (logical 1), if I
P
≤ pickup setting 51P1P and the phase time-overcurrent element
is fully reset
= 0 (logical 0), if I
P
≤ pickup setting 51P1P and the phase time-overcurrent element
is timing to reset (not yet fully reset)