Date Code 20000421
Specifications
2-7
SEL-251, -2, -3 Instruction Manual
F
UNCTIONAL
S
PECIFICATIONS
Note
:
Overcurrent Elements: Values shown are for 5-amp nominal current input models. (Divide
current values by five for 1-amp nominal current input models.)
Phase Overcurrent Elements for Phase and Three-Phase Faults - See Figure 2.18 and
Figure 2.21
51T
Phase Time-Overcurrent Element
•
Curve families: moderately inverse, inverse, very inverse, extremely inverse
•
Time dial: 0.5 to 15.00 in 0.01 steps
•
Pickup (
51P
): 1 to 12 A
±
2% of setting
±
0.1 A secondary
•
Time delay or 1-cycle reset time
•
Timing:
±
5% and
±
1 cycle for currents between 2 and 20 multiples of pickup
•
Internally and externally torque controllable
50LT
Phase Definite-Time Overcurrent Element
•
Pickup (
50L
): 0.5 to 100 A
±
2% of setting
±
0.1 A secondary
•
Time delay: 0 to 16,000 cycles in 1-cycle steps
•
Internally and externally torque controllable
50H
Phase Instantaneous Overcurrent Element
•
Pickup: 0.5 to 100 A
±
2% of setting
±
0.1 A secondary
•
Internally and externally torque controllable
50C
Phase Instantaneous Overcurrent Element
•
Pickup: 0.5 to 100 A
±
2% of setting
±
0.1 A secondary
•
Can be used to override voltage control through TCI setting choice
Negative-Sequence Overcurrent Elements for Phase-to-Phase Faults - See Figure 2.19
51QT
Negative-Sequence Time-Overcurrent Element
•
Element measures 3 I
2
negative-sequence current
•
Curve families: moderately inverse, inverse, very inverse, extremely inverse
•
Time dial: 0.5 to 15.00 in 0.01 steps.
•
Pickup (
51QP
): 1 to 12 A
±
3% of setting
±
0.18 A secondary
•
Time delay or 1-cycle reset time
•
Timing:
±
5% and
±
1 cycle for currents between 2 and 20 multiples of pickup
•
Externally torque controllable
50QT
Negative-Sequence Definite-Time Overcurrent Element
•
Element measures 3 I
2
negative-sequence current
•
Pickup (
50Q
): 0.5 to 100 A
±
3% of setting
±
0.18 A secondary
•
Time delay: 0 to 16,000 cycles in 1-cycle steps
•
Externally torque controllable