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S&C TripSaver ™ Dropout Recloser For enhanced lateral circuit protection at 15.5 kV and 25 kV
S&C TripSaver™ Dropout RecloserFor enhanced lateral circuit protection
at 15.5 kV and 25 kV
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Conventional lateral circuit protection requires some concessionsOver 90% of temporary faults on overhead distribution circuits occur on laterals. Over the years, utilities have dealt with lateral protection a couple of ways.
Some utilities employ a “fuse blowing” philosophy: The substation feeder breaker is properly coordinated with the lateral fuse, so that the fuse will clear any downstream fault within its rating . . . not the breaker. The problem: Service to customers on the lateral is permanently interrupted—even for a temporary fault—as shown in Figure 1. And the utility must deal with the high cost of service calls to replace lateral fuses.
Figure 1. “Fuse blowing” philosophy.
Other utilities employ a “fuse saving” philosophy: The first trip of the substation feeder breaker is intentionally miscoordinated so that the breaker operates faster than the lateral fuse to clear a fault downstream of the lateral fuse. The second trip of the breaker is slower so that if the fault is still present, the lateral fuse will operate to clear it. The problem: All customers on the feeder experience a momentary interruption for all faults—as shown in Figure 2.
Figure 2. “Fuse saving” philosophy.
TripSaver provides better lateral protectionS&C’s new TripSaver Dropout Recloser eliminates these problems. It’s ideally suited for protection of laterals that experience frequent momentary faults. This self-powered, electronically controlled, single-phase vacuum fault interrupter is available for installation in new or existing cutout mountings. A two-insulator, branch-feeder style mounting is also available.
TripSaver eliminates the permanent outage which results when the lateral fuse operates in response to a momentary fault. Utilities using “fuse blowing” will see an improvement in SAIFI without sacrificing MAIFI.
And TripSaver eliminates the momentary interruption on the feeder in instances where the breaker is tripped to save the lateral fuse during a momentary fault. Utilities using “fuse saving” will see an improvement in MAIFI without sacrificing SAIFI.
As shown in the following table, TripSaver offers a number of advantages over traditional lateral protection devices.
Introducing S&C’s new TripSaver Dropout Recloser:
A better solution for overhead lateral circuit protection at 15.5 kV and 25 kV
Feeder breaker
Lateral fuse
Feeder breaker
Lateral fuse
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Comparison of Lateral Protective Devices
Feature/Benefit Single-Phase Hydraulic Recloser
Dropout-Style Electronic
SectionalizerTripSaver
Easy to install 4 4
Low initial price 4 4
Low installation cost 4 4
Fault-interrupting capability 4 4
Easy to reset 4 4
Electronic control 4 4
No bypass switch required 4 4
Light weight compared to oil reclosers 4 4
No battery backup required 4 4
Fits in cutout mounting 4 4
No momentary outage on the main feeder for lateral faults
4 4
TripSaver’s operating sequenceTripSaver features an open-close-open-dropout operating sequence with a 5-second reclosing time interval. The interrupter resets five seconds after dropout, ready for the next sequence. The first opening operation features very fast—1.5- to 3.5-cycle—clearing time, as shown in Figure 3. The
second opening operation features a time-current characteristic equivalent to either a K-speed or T-speed fuse curve, as shown in Figure 4. This operating sequence provides excellent coordination with the substation feeder breaker and downstream transformer fuses.
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1
0.1
0.01 100 1000
Current, Amperes
Tim
e, S
econ
ds
10000
1st Shot(fast)
2nd Shot (slow)
IAC77 640A, TD7
10
1
0.1
0.01 100 1000
Current, Amperes
Tim
e, S
econ
ds
10000
1st Shot (fast)
2nd Shot(slow)
IAC77 640A, TD7
Figure 3. First opening operation (fast curve) in red. Figure 4. Second opening operation (slow curve) in red.
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TripSaver recloses, restoring power to customers served from the lateral, as shown in Figure 7. Since the fault was temporary and has gone away, a second opening operation isn’t needed. TripSaver reverts to its fast curve after 15 seconds.
How TripSaver works for a temporary faultConsider a temporary fault downstream of TripSaver, as shown in Figure 5.
Figure 6. TripSaver opens.
As discussed on page 3, the first opening operation uses the fast curve, which is coordinated with the substation feeder breaker relay, as shown in Figure 3.
TripSaver opens, as shown in Figure 6. Only customers served from the lateral experience a momentary interruption.
Figure 7. TripSaver recloses.
TripSaver
Figure 5. Temporary fault.
Feeder breaker
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How TripSaver works for a permanent faultConsider a permanent fault downstream of TripSaver, as shown in Figure 8.
As before, the first opening operation uses the fast curve, which is coordinated with the substation feeder breaker relay, as shown in Figure 3.
TripSaver opens, as shown in Figure 9. Again, only customers served from the lateral experience a momentary interruption.
Figure 9. TripSaver opens. Figure 11. TripSaver drops out.
Since the fault is permanent, TripSaver opens again per the slow curve, as shown in Figure 4. Power is interrupted to all customers on the lateral.
Then TripSaver drops out in the same manner as a standard fuse cutout, providing visual indication that the faulted section of the feeder has been isolated, as shown in Figure 11.
TripSaver recloses, as shown in Figure 10.
Figure 10. TripSaver recloses.Figure 8. Permanent fault.
TripSaver
Feeder breaker
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Handling TripSaver—Overhead Pole-Top Style Shown
TripSaver in dropout position Closing TripSaver back into mounting
Opening TripSaver with Loadbuster® Tool
Five seconds after TripSaver drops out, the vacuum fault interrupter closes.
TripSaver can be readily closed back into the mounting using a standard hookstick equipped with a distribution prong.
If the lateral circuit needs to be de-energized, TripSaver can be opened using Loadbuster—The S&C Loadbreak Tool.
MaintenanceUnlike other single-phase reclosers, TripSaver requires no routine maintenance, field programming, or batteries for back-up power.
ConstructionBirdproof-design insulator—higher insulation characteristics than ANSI distribution-cutout standards. Porcelain insulator shown; composite-polymer silicone insulator also available. NEMA Type B and extended mounting brackets are available too
Parallel-groove connector—tin-plated cast red brass. For ease of connection, accommodates two conductors, even of unlike size. Other types of connectors are also available
Upper contact—silver-to-silver; stainless-steel spring provides high contact pressure
Rugged attachment hooks for Loadbuster—guide TripSaver during closing
Vacuum fault interrupter
Lower contacts (not visible)—silver-to-silver; provide dual current path, independent of hinge pivot
Trunnion—high-strength cast bronze, silver plated. Surfaces around trunnion bear on broad hinge surfaces to keep TripSaver in alignment during closing
Mode selector — for selecting automatic reclosing or non-reclosing operation. Non-reclosing mode has one-shot-to-lockout operation, suitable for use when crews are working downstream of the TripSaver
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Branch-Feeder Style. Includes mounting (less connectors)
15 15 15.5 110
30 1250
17 (432)h
50 2000l
100 4000f
15/25a 15 15.5 150
30 1250
50 2000l
100 4000f
25 25 29 150
30 1250
50 2000l
100 4000f
RatingsComplete TripSaver—For new installations.
50/60-Hz Ratings Leakage Distance
to Ground Minimum,
Inches (mm)
kV Amperes, RMS
System Class Nom. Max BIL Cont. Interr.,
Sym.
Overhead Pole-Top Style. Includes mounting (less mounting bracket and connectors)
15 15 15.5 110
30 1250
8.5 (216) 50 2000l
100 4000f
15/25a 15 15.5
125
30 1250
11 (279) 50 2000l
100 4000f
150
30 1250
17 (432) 50 2000l
100 4000f
25 25 29
125
30 1250
11 (279) 50 2000l
100 4000f
150
30 1250
17 (432) 50 2000l
100 4000f
TripSaver Less Mounting—For installation in existing S&C Type XS Fuse Cutout Mountings
Item
For use with S&C Type XS Fuse Cutout
Basic Catalog
50/60-Hz Ratings
kV Amperes, RMS
System Class Nom. Max Cont. Interr., Sym.
TripSaver
89021, 89031 15 15 15.5
30 1250
50 2000l
100 4000f
89022, 89032, 89042, 89052
15/25a 15 15.5
30 1250
50 2000l
100 4000f
89022, 89032, 89042, 89052
25 25 29
30 1250
50 2000l
100 4000f
a Applicable for protection of single-phase-to-neutral circuits only where the leakage distance to ground meets user’s requirements.l Meets the requirements of IEEE C37.60-2003 for reclosers having vacuum fault interrupters rated 2 kA.
f Meets the requirements of IEEE C37.60-2003 for reclosers having under-oil interrupters rated 4 kA, and for those having vacuum fault inter-rupters rated 2 kA.h Leakage distance to ground is 24.2 inches (615 mm) for mountings with Cypoxy insulators.
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Styles
Catalog Number 99042-K100-P, featuring composite polymer silicone insulator. Complete Overhead Pole-Top Style TripSaver rated 25 kV; 29 kV maximum, 150 kV BIL; 100 amperes continuous; 4000 amperes interrupting, RMS symmetrical; 17 inches (432 mm) leakage distance to ground.
Catalog Number 99022-K100. Complete Overhead Pole-Top Style TripSaver rated 25 kV; 29 kV maximum; 125 kV BIL; 100 amperes continuous; 4000 amperes interrupting, RMS symmetrical; 11 inches (279 mm) leakage distance to ground.
Ice Hood Option “-H1,” allows TripSaver to drop open with Z\v-inch ice build up.
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Catalog Number 199021-E-K100 Complete Branch-Feeder Style TripSaver rated 15 kV nominal, 15.5 kV maximum, 110 kV BIL, 100 amperes continuous, 4000 amperes interrupting, RMS symmetrical, 17 inches (432 mm) leakage distance to ground.
Catalog Number 99122-K100 Complete Overhead Pole-Top Style TripSaver rated 15/25 kV nominal, 15.5 kV maximum, 125 kV BIL, 100 amperes continuous, 4000 amperes interrupting, RMS symmetrical, 11 inches (279 mm) leakage distance to ground.
Offices Worldwide f www.sandc.com
Descriptive Bulletin 461-30 April 14, 2008©
