S C Electric Company VacuFuse II Self Resetting Interrupter Instruction Manual

S C Electric Company VacuFuse II Self Resetting Interrupter

Specifications:

• Product Name: VacuFuse II Self-Resetting Interrupter
• Application: Fault-testing technology at the grid edge
• Features: Self-resetting interrupter, lateral protection, user-designated TCC curve
• Compatibility: Single-phase overhead distribution transformers up to 167 kVA on 15-kV class systems and up to 250 kVA on 25-kV class systems

Product Usage Instructions

Overview
The VacuFuse II Self-Resetting Interrupter is designed to improve customer satisfaction by eliminating nuisance outages at the edge of the grid. It brings fault-testing technology to prevent unnecessary sustained outages and lower maintenance costs.

Application

• How It Works: The self-resetting interrupter responds to both temporary and permanent faults, restoring power in case of temporary faults and preventing permanent outages. It comes factory-configured with a user-designated time-current characteristic (TCC) curve for optimized performance.
• Installation: The device is designed for easy deployment and can be installed above single-phase overhead distribution transformers on 15-kV or 25-kV class systems. Installation takes only minutes using existing S&C cutout mountings.

Construction
The VacuFuse II features a weather-resistant enclosure that houses the vacuum interrupter, ensuring durability in various environmental conditions.

FAQ:

• Q: How does the VacuFuse II prevent unnecessary sustained outages?
  A: The VacuFuse II Self-Resetting Interrupter responds to faults at the grid edge, restoring power in case of temporary faults and preventing them from becoming permanent outages, thus reducing maintenance costs and improving grid reliability.

• Q: Can utilities customize the time-current characteristic curve of the interrupter?
  A: Yes, utilities can choose from preset TCC curves like K, KS, T, or the S&C transformer-protection (TXP) speed. Selecting the TXP Speed curves can further reduce nuisance tripping and protect the transformer effectively.

Fault-testing at the grid edge eliminates nuisance outages, saving truck-roll costs and improving customer satisfaction.

Overview

IMPROVE CUSTOMER SATISFACTION

• As storms become more severe and as more and more people work from home, outages at the edge of the grid are having a greater impact than ever.
• Often, the cause is a blown fuse above an overhead distribution transformer that can occur regardless of whether the fault was temporary or permanent. Issues at the edge of the grid tend to cluster into pockets, and these troublesome areas often remain undetected when averaging interruption metrics, such as with SAIDI (System Average Interruption Duration Index) and SAIFI (System
• Average Interruption Frequency Index), across the system. Yet, these hotspots are clear when using consumer-centric metrics, such as CEMI (Customers Experiencing Multiple Interruptions).
• Repeated disruptions impact customer satisfaction and increase maintenance costs from unnecessary truck rolls. In fact, industry sources reveal that 70% of overhead distribution transformer fuse operations are classified as nuisance outages, where no other repair work is needed. See Figure 1.

LATERAL PROTECTION—EVEN AT THE EDGE OF THE GRID

• The VacuFuse II Self-Resetting Interrupter brings fault-testing technology to the grid edge. As a result, it boosts grid-edge reliability, prevents unnecessary sustained outages, and subsequently lowers maintenance expenses.
• This depth of lateral protection not only optimizes system performance but also crews’ time by eliminating the cost of sending teams to work on avoidable or nuisance repairs. And because the device is designed for easy deployment, installation takes only minutes when using existing S&C cutout mountings.

Application

HOW IT WORKS

• VacuFuse II Self-Resetting Interrupters solve the nuisance outages that occur on overhead distribution transformers. As a single-phase, self-resetting interrupter intended for use on single phase overhead distribution transformers on 15‑kV class systems (transformer primary voltages of 7.2–9.0 kV) or 15- and 25‑kV class systems (transformer primary voltages of 7.2–15.5 kV), it replaces fuses in these locations. When the self-resetting interrupter detects a fault, its vacuum interrupter will open to interrupt the fault current.
• If the fault is temporary, the self-resetting interrupter will restore power. See Figure 2.
• This saves temporary faults from becoming permanent outages and eliminates the maintenance costs otherwise associated with refusing and restoration.
• If the fault is permanent, the self-resetting interrupter will interrupt the fault current, wait 45 seconds, reclose, and then interrupt the fault current and de-energize the transformer. See Figure 3. Like a standard fuse or the TripSaver® II Cutout Mounted recloser, the VacuFuse II Self-Resetting Interrupter drops open on permanent outages. After the line crew has cleared the fault, the self-resetting interrupter can be closed back into the cutout mounting, restoring power to the transformer after 45 seconds.
• This self-resetting interrupter comes factory-configured with a user-designated time-current characteristic (TCC) curve.
• Utilities can choose from any of the following TCC curves: K, KS, T, or the S&C transformer-protection (TXP) speed.
• If a company’s operating procedures allow for selecting a new TCC curve, consider selecting the TXP Speed curves, which hug the transformer

Construction

• A Silicone over-molded enclosure—A weather-resistant enclosure houses the vacuum interrupter.
• B Vacuum Interrupter—Located in the upper insulator, it quietly contains and interrupts the fault without exhaust or sparking.
• C Hand grip—The body shape and material allow easy handling and installation.
• D Manual operating lever—This lever allows manual closing (with sufficient voltage present) and manual opening of the vacuum interrupter. When the lever is moved to the Down position, the vacuum interrupter will open immediately. Moving the lever to the Up position closes the vacuum interrupter only after the unit has achieved full charge, as indicated by the solid white READY TO CLOSE LED at the bottom of the unit. The manual operating lever features a ring that can be used to apply tags. Note: When the VacuFuse II Self-Resetting Interrupter trips, the lever does not move. The lever only indicates the last manual operation, not the Open or Closed state of the vacuum interrupter.
• E Position indicator—This indicates the position of the vacuum interrupter, with a red color signaling closed and a green color signaling open. Note: Refer only to the Position indicator, not to the manual operating lever, for vacuum interrupter status.
• F CHARGING LED—When powered and the vacuum interrupter is open, this white LED will flash at one-second intervals to indicate the device is charging. Charging time is 45 ± 10 seconds. When performing an automatic delayed close, the CHARGING LED will continue flashing while the READY TO CLOSE LED is illuminated. When the device is not powered or when the vacuum interrupter is closed, this LED will not flash.
• G READY TO CLOSE LED—This white LED will remain lit when the unit has achieved full charge and is ready to close the vacuum interrupter.

Options

TCC CURVES
VacuFuse II interrupters come ready to install, streamlining the commissioning process and lessening the amount of training for line crews. Four TCC speed families are available, all of which are optimized for transformer protection. The K, KS, and T speed fuse emulations have definite times at high current for single-cycle clearing of high-magnitude faults. S&C’s TXP speed curve has these definite time elements while hugging the transformer damage curve at lower currents—providing maximum protection against nuisance tripping.

NON-FAULT-TESTING MODELS
In addition to fault-testing models, VacuFuse II interrupters are also available without faulttesting. Non-fault-testing (single-shot) VacuFuse II interrupters have an Open-Dropout operating sequence and are well-suited for transformer protection applications where reclosing is not desirable.

MULTI-PACK PACKAGING
Large orders of VacuFuse II interrupters can be shipped palletized in multi- pack boxes to enable easier bulk handling, a reduction in packaging materials, and outdoor storage. Single-pack packaging is also available for individual handling and is for indoor storage only.

REVERSE-COLOR POSITION INDICATOR
For customers in regions that use red to signify an Open position and green to signify a Closed position

Ratings
Table 1. Complete VacuFuse II Self-Resetting Interrupter—for a new installation; includes VacuFuse II interrupter, cutout mounting (less mounting bracket), and connectors

Cutout Mounting Size, kV| Phase-to-neutral voltage rating, kV| ****

BIL, kV 1

| Amperes Cont., RMS 2| Amperes Interr., Sym
---|---|---|---|---
15| 7.2–9.0| 110| 20| 6 300
25| 7.2–9.0| 150| 20| 6 300
15| 7.2–15.5| 110| 20| 6 300
25| 7.2–15.5| 150| 20| 6 300

1. BIL is achieved with the VacuFuse II interrupter dropped open.
2. Available in 2–20 ampere models, with minimum trip currents from 4–40 amperes.

Table 2. VacuFuse II Self-Resetting Interrupter Only—for retrofit in an existing present-production (“-R10” or “-R11”) S&C-only cutout mounting

Cutout Mounting Size, kV| Phase-to-neutral voltage rating, kV| ****

BIL, kV 1

| Amperes Cont., RMS 2| Amperes Interr., Sym
---|---|---|---|---
15| 7.2–9.0| 110| 20| 6 300
25| 7.2–9.0| 125/150| 20| 6 300
15| 7.2–15.5| 110| 20| 6 300
25| 7.2–15.5| 125/150| 20| 6 300

1. BIL is achieved with the VacuFuse II interrupter dropped open, and is dependent on the cutout mounting into which the interrupter is installed.
2. Available in 2–20 ampere models, with minimum trip currents from 4–40 amperes.

Table 3. Available Ampere Ratings and TCC Curves1

K, T, and KS Speed curves for VacuFuse II interrupters are fuse emulations with definite time elements at high current. See S&C Information Bulletin 466–211 and TCC Number 466-7 for complete TCC information.

CONTACT YOUR S&C SALES REPRESENTATIVE FOR MORE INFORMATION
sandc.com
466-30 102323
© S&C Electric Company 2022-2023, all rights reserved

References

• S&C Electric Company

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