Schweitzer Engineering Laboratories SEL-321 - Fault Locator Enable and Line Length; Positive- and Zero-Sequence Line Impedances; Enable Desired Distance Zones and Directional Sense

Date Code 20011026 Applications 5-3
SEL-321/321-1 Instruction Manual
Positive- and Zero-Sequence Line Impedances
The positive- and zero-sequence secondary impedance values should match those calculated for
Line 2. All settings for the SEL-321 Relay are in secondary quantities. The primary impedances
must be divided by the ratio of the selected potential transformer ratio (PTR) to the current
transformer ratio (CTR).
Fault Locator Enable and Line Length
This setting allows you to enable or disable the fault locating function or use a radial fault
locating method. In this example, as with most applications, the fault locating capability of the
relay is desired. The line length is selected to match the distance between Bus B and Bus C.
Current and Potential Transformer Ratios
The CTR selected for this example is 1000:5 or 200:1. The PTR selected for this example is
2000:1.
For the relay at Breaker 3:
RELID = SEL
SELSEL
SEL-
--
-321 POTT
321 POTT321 POTT
321 POTT
TRMID = EXAMPL
EXAMPLEXAMPL
EXAMPLE: BUS B, BREAKER 3
E: BUS B, BREAKER 3E: BUS B, BREAKER 3
E: BUS B, BREAKER 3
Z1MAG = 7.80
7.807.80
7.80
Z1ANG = 83.97
83.9783.97
83.97
Z0MAG = 24.79
24.7924.79
24.79
Z0ANG = 81.46
81.4681.46
81.46
LOCAT = Y
YY
Y
LL = 100.00
100.00100.00
100.00
CTR = 200.0
200.0200.0
200.0
PTR = 2000.0
2000.02000.0
2000.0
- Other Settings Affected
Values entered for Z1MAG, Z1ANG, Z0MAG, Z0ANG, and LL are used in the fault locator
calculations. Z1ANG also sets the maximum torque angle for the phase and ground mho
distance elements.
Enable Desired Distance Zones and Directional Sense
The number of phase mho, ground mho, and quadrilateral distance zones is selectable from zero
to four. Each number of distance elements is independently selectable. For example, if the
quadrilateral ground distance element is not used, set the QUADZ to N.
Once the number of distance element zones is selected, only the elements necessary for the
number of selected zones require settings. This includes the distance element reaches and the
supervisory overcurrent settings.
Each distance element zone and residual and negative-sequence overcurrent level direction is
independently set for forward or reverse directional sense. All four distance element zones and
residual and negative-sequence overcurrent levels must be selected for forward (F) or reverse (R)
direction sense.