Schweitzer Engineering Laboratories SEL-311C - Table 3.10 Phase Time-Overcurrent Element (Maximum Phase) Logic Outputs; Figure 3.24 Phase Time-Overcurrent Element 51 PT

3.34
SEL-311C Relay Instruction Manual Date Code 20060320
Distance, Out-of-Step, Overcurrent, Voltage, Synchronism Check, and Frequency Elements
Time-Overcurrent Elements
Figure 3.24 Phase Time-Overcurrent Element 51PT
Accuracy
51PT Element Logic Outputs
The logic outputs in Figure 3.24 are the Relay Word bits shown in Table 3.10.
51PT Element Torque Control Switch Operation
Torque Control Switch Closed
The pickup comparator in Figure 3.24 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:
51PP
(max. phase)
I
ABC
Setting
51PTC
Torque Control Switch
SEL
OGIC
Torque Control
51PT Phase
Time-Overcurrent Element
Curve Timing and Reset Timing
Settings
51PP Pickup
51PC Curve Type
51PTD Time Dial
51PRS Electromechanical
Reset? (Y/N)
Pickup
Curve
Timeout
Reset
51P
51PR
51PT
Torque Control
51PTC State Switch Position
Logical 1 Closed
Logical 0 Open
Logic Point 51PTC Controls the Torque Control Switch
Setting
51PRS = Reset Timing
Y Electromechanical
N 1 Cycle
Relay
Word
Bits
SELOGIC
Setting
Pickup
±0.05 A secondary and ±3% of setting
(5 A nominal phase current inputs, IA, IB, IC)
±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
Table 3.10 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 and Target Logic on
page 5.1.
51PT Phase time-overcurrent
element is timed out on its curve.
Tripping and other control
applications. See Trip and Target
Logic.
51PR Phase time-overcurrent
element is fully reset.
Element reset testing or
other control applications.