Schweitzer Engineering Laboratories SEL-321 - Page 31

Date Code 20011026 Specifications 2-7
SEL-321/321-1 Instruction Manual
Outputs Phase Residual Neg.-Seq.
Pickup 51PP 51NP 51QP
Timed Out 51PT 51NT 51QT
Resetting 51PR 51NR 51QR
Supporting Drawings: Figure 2.23 through Figure 2.26.
INSTANTANEOUS/DEFINITE-TIME OVERCURRENT ELEMENTS: LEVELS 1 - 4
Zero to four levels of residual and negative-sequence overcurrent protection can be individually
selected, using the E50N and E50Q settings respectively.
Settings
Level 1 Level 2 Level 3 Level 4
I
R
>> 50N1 50N2 50N3 50N4
3I
2
>> 50Q1 50Q2 50Q3 50Q4
Instantaneous
Nondirectional Outputs
I
R
>> 50N1 50N2 50N3 50N4
3I
2
>> 50Q1 50Q2 50Q3 50Q4
The appropriate 50Q1 - 50Q4 element must be enabled and set to provide unbalanced fault
detection for OOS blocking in phase distance trip logic.
Instantaneous
Directional Outputs
Level 1 Level 2 Level 3 Level 4
I
R
>> 67N2 67N3 67N4
3I
2
>> 67Q2 67Q3 67Q4
Time Delayed
Directional Outputs
I
R
>> 67N1 67N2T 67N3T 67N4T
3I
2
>> 67Q1 67Q2T 67Q3T 67Q4T
The negative-sequence directional elements, 32QF and 32QR, provide the directional supervision
for 67N1 - 67N4 and 67Q1 - 67Q4 elements. The 32QF element supervises the forward-looking
overcurrent elements, while the 32QR element supervises those set in the reverse direction.
Forward set elements are supervised by SPO. All elements are supervised by fault selection
logic when ESPT = N1 or Y1. The nondirectional outputs are always available.
Each level of residual and negative-sequence overcurrent protection has a designated settable
timer.
Supporting Drawings: Figure 2.27 and Figure 2.28.
ADDITIONAL VOLTAGE ELEMENTS
The relay contains seven independent voltage elements. Use these elements by themselves or in
combination with other relay elements using the programmable output contact logic to create
custom control and supervision schemes. Possible applications might include undervoltage
supervision of instantaneous overcurrent elements, local and remote overvoltage alarms, etc.