Instruction Manual
Table Of Contents
- Major Features and Benefits
- Functional Overview
- System Overview
- Application Examples
- Collect Fault Information From Remote Branches
- Improve Fuse Coordination
- Fuse-Blowing Scheme Shortcomings
- Improve Fuse-Blowing Schemes With the Fault Transmitter and Receiver System
- Fuse-Saving Combined With Fuse-Blowing Schemes
- Improve Feeder Cable First-Span Protection
- Implement a Low-Cost Fast Bus-Tripping Scheme
- Tripping the Right Recloser Faster
- Safety Information
- Network Deployment Overview
- Device Installation
- Dimensions
- Specifications
- Appendix A: Manual Versions
- Appendix B: Two-Branch Application
- Appendix C: Link Budget Analysis
- Appendix D: SEL-RP50 Fault Repeater Detailed Implementation
- Technical Support
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SEL-FT50/SEL-FR12 Fault Transmitter and Receiver System Instruction Manual Date Code 20210405
Appendix B: Two-Branch Application
Appendix B: Two-Branch Application
This application has two three-phase branches, A and B, as shown in Figure 30.
Branch B has a fuse and uses a fuse-blowing scheme, while Branch A does not.
When a fault occurs on Branch A, the recloser operates to clear the fault. In tradi-
tional protection schemes, those without the SEL-FT50/SEL-FR12 system, the
time-inverse overcurrent curves of the SEL-651R recloser control are set above
the fuse-clearing curve, resulting in longer tripping times for faults on Branch A.
Use the SEL-FT50/SEL-FR12 system to improve this protection scheme.
Insert a set of three SEL-FT50 Fault Transmitters on each branch, one per phase.
The SEL-FR12 connects to the SEL-651R with an SEL-C272 serial cable. In this
example, the load current of Branch A is 200 A, and the load current of Branch B
is 100 A. The 51 element pickup of the SEL-651R is set above 200 percent of the
load current. In this example, the fuse size is 140 T, the SEL-651R 51 element
pickup is 550 A, and the settings from Table 16 apply.
D = switch is in the DOWN or OFF position.
U = switch is in the UP or ON position.
This settings example uses Network ID = 3, and the fault current pickup thresh-
old is set above the load current and below the pickup.
The Network ID of the SEL-FR12 matches the Network ID of the SEL-FT50
Fault Transmitters. Table 17 assumes that the SEL-FT50 Fault Transmitters
require High Gain mode selections (see Receive Signal Strength Indicator on
page 26 for details). See Table 18 for the settings of the SEL-651R and Table 19
for the SEL-651R transmit M
IRRORED BITS settings.
Figure 30 SEL-FT50/SEL-FR12 System Protection Scheme
R
SEL-FR12
SEL-651R-2
SEL-FT50
SEL-FT50
1
2
3
4
5
6
A
B
Table 16 Settings for the SEL-FT50 Fault Transmitters
SEL-FT50 Branch
Unit ID Control
(DIP) Switch
Positions
Network ID Control
(DIP) Switch
Positions
Pickup Threshold
Control (DIP)
Switch Positions
1 A 1—(DDDD) 3—(DDUD) 400 A—(DUU)
2 A 2—(DDDU) 3—(DDUD) 400 A—(DUU)
3 A 3—(DDUD) 3—(DDUD) 400 A—(DUU)
4 B 4—(DDUU) 3—(DDUD) 200 A—(DUD)
5 B 5—(DUDD) 3—(DDUD) 200 A—(DUD)
6 B 6—(DUDU) 3—(DDUD) 200 A—(DUD)