Vista® SD Underground Distribution Switchgear

For outdoor distribution, 17.5 kV and 29 kV

Introducing the industry’s first practical solid-dielectric switchgear with a visible open gap and field-replaceable bushings

S&C now offers another choice in metal-enclosed gear. Economical new Vista SD Underground Distribution Switchgear is the first practical solid-dielectric switchgear with a visible open gap and field-replaceable bushings. It features:

Visi-Gap® Load-Interrupter Switches. These vacuum load-interrupter switches provide three-pole live switching of 600-amp main feeders. The switches comply with IEEE Standard 1247 and IEC Standard 62271-103.
Visi-Gap® Fault Interrupters. These microprocessor-controlled vacuum fault interrupters provide three-pole live switching and protection of 600-ampere main feeders and 200- or 600-ampere taps, laterals, and sub-loops. Fault interrupters comply with both IEEE Standard C37.60 and IEC Standard 62271-111.

The elbow-connected switches and fault interrupters are encapsulated in an environmentally friendly solid-dielectric insulating material.

Features

Vista SD Switchgear can be furnished with up to six “ways” (load-interrupter switches and/or fault interrupters), in ratings through 29 kV and 16 kA symmetrical interrupting. By handling more loads per assembly, fewer Vista SD Switchgear assemblies are required. Each load-interrupter switch and fault interrupter includes a manually operated, two-position isolating disconnect to provide a visible open gap.

Easy-to-follow mimic bus and indicators on the front of the switchgear convey the position of each switch and fault interrupter and its isolating disconnect — and whether a fault interrupter has tripped in response to a fault.
Easy-to-operate manual operating mechanism. Operating mechanisms for fault interrupters are “trip-free” . . . the opening spring is charged when the closing spring is charged, and will open the fault interrupter — based on the TCC curve in the overcurrent control — if the fault interrupter is closed into a fault.
Factory-installed and wired motor operators, to facilitate remote power operation of load-interrupter switches and fault interrupters; are optionally available. The operators can be decoupled to permit testing of the motor and controls.
Completely submersible and suitable for application in subsurface vaults subject to flooding. It is also available for above-grade application, in pad-mounted style enclosures.
Considerably smaller than traditional air-insulated gear. So it can be installed exactly where it’s needed without compromising aesthetics. Consumers are happier and you save money through reduced trenching and shorter cable runs.

Simple to Operate

With Vista SD Underground Distribution Switchgear, routine operation, such as isolating a downstream cable for repair, is easy. Just one person, using either the manual handle or a suitable user-furnished universal pole equipped with a standard fitting, merely needs to:

Place the load-interrupter switch or fault interrupter operating mechanism in the “open” position, then confirm the open gap of the isolating disconnect through the large viewing window.
Test for voltage using the optional potential indication feature.

Vista SD Switchgear is furnished with a ground connection pad on each load-interrupter switch and fault interrupter, for terminating cable concentric neutrals. A continuous ground bus for the entire switchgear assembly is optionally available.

Complete System Coordination

Vista SD Underground Distribution Switchgear is furnished with the same microprocessor-based overcurrent control used in S&C Vista® Underground Distribution Switchgear. This proven reliable device offers special,. customizable “coordinating” speed time-current characteristic curves that provide complete coordination with upstream relays and downstream fuses. Conventional “E” and “K” speed curves are available too.

Separate phase- and ground-overcurrent curves coordinate with source-side circuit breakers having ground-trip settings. Both main and tap curves are included for complete coordination between fault interrupters applied on main feeders and those applied on subloop taps.

The overcurrent control is programmed with a PC, in the shop or in the field. There are no knobs or dials to compromise security. The control features an event recorder that captures information on the last twelve operations of each fault interrupter.

External trip provisions are optionally available, permitting the fault interrupters to be tripped remotely by external controls or relays.

Installation Styles

Pad-Mounted Style Vista SD Underground Distribution Switchgear

Vista SD can be furnished with an optionally available pad-mounted style enclosure for above-grade installations. Pad-mounted enclosure meets IEEE C57.12.28 and C57.12.29. Available in mild steel or stainless steel.

Multi-Way Vault-Mounted Style Vista SD Underground Distribution Switchgear

Multi-way Vista SD switchgear can be used in submersible vaults with multiple source ways and/or multiple protected ways (taps).

Single-Way Vault-Mounted Style Vista SD Underground Distribution Switchgear

Single-way Vista SD switchgear is ideally suited for use on the primary side of network transformers. Model 101 (fault interrupter) shown.

Vista SD Underground Distribution Switchgear—PMH and PME Configurations

PMH and PME configurations of Vista SD switchgear match the footprint and phase configuration of PMH and PME Pad-Mounted Gear.

Ratings

Pad Mount and Vault Configurations
50/60-Hz IEEE Ratings — (IEC ratings in parenthesis)
Voltage, kV			Amperes, RMS
System Class	Max	BIL	Main Bus		Visi-Gap® Load-Interrupter Switch			Visi-Gap® Fault Interrupter
System Class	Max	BIL	Continuous Current	Short-Circuit, RMS, Symmetrical	Continuous, Load Dropping, and Load Splitting	Momentary and Three-Second, Symmetrical	Three-Time, Duty-Cycle, Fault Closing, Symmetrical	Continuous, Load Dropping, and Load Splitting	Short-Circuit Interrupting
15 (12)	17.5 (17.5)	95 (75)	600 (630)	16 000	600 (630)	16 000	16 000	600 (630)	16 000
27 (24)	29 (29)	125 (125)	600 (630)	12 500	600 (630)	16 000	16 000	600 (630)	12 500

Applicable to fault closing into Closed position.

200 amperes if fault interrupters are furnished with optional 200-ampere bushings.

12 500 amperes if fault interrupters are furnished with optional 200-ampere bushings.

PMH and PME Configurations
50/60-Hz IEEE Ratings — (IEC ratings in parenthesis)
Voltage, kV			Amperes, RMS
System Class	Max	BIL	Main Bus		Visi-Gap® Load-Interrupter Switch			Visi-Gap® Fault Interrupter
System Class	Max	BIL	Continuous Current	Short-Circuit, RMS, Symmetrical	Continuous, Load Dropping, and Load Splitting	Momentary and Three-Second, Symmetrical	Three-Time, Duty-Cycle, Fault Closing, Symmetrical	Continuous, Load Dropping, and Load Splitting	Short-Circuit Interrupting
15 (12)	17.5 (17.5)	95 (75)	600 (630)	16 000	600 (630)	16 000	16 000	200 (200)	12 500
27 (24)	29 (29)	125 (125)	600 (630)	12 500	600 (630)	12 500	12 500	200 (200)	12 500

Parallel or loop switching. Load-interrupter switches and fault interrupters can switch the magnetizing current of transformers associated with this rating. Unloaded cable-switching capability: 10 amperes at 17.5 kV; 20 amperes at 29 kV. Load-interrupter switches and fault interrupters can also switch single capacitor banks through 1800 kvar.

Applicable to fault closing into Closed position.

600 amperes if fault interrupters are furnished with optional 600-ampere bushings.

16 000 amperes if fault interrupters are furnished with optional 600-ampere bushings.

Circuit Configurations

Model number indicates the total number of ways, as well as the number of load-interrupter switch ways and fault-interrupter ways. For example, Model 431 has “4” ways—“3” load-interrupter switch ways and “1” fault-interrupter way.

Pad Mount and Vault Configurations

PMH and PME Configurations

Overcurrent Control

Vista SD Underground Distribution Switchgear furnished with fault-interrupter ways includes a unique microprocessor-based overcurrent control that detects faults and initiates operation of the resettable fault interrupters. Program the control in the shop or in the field using your personal computer via an easily connected USB port. The control offers exceptional flexibility and reliability, and it includes features unavailable as standard offerings in other manufacturers’ devices:

Five families of curves: Standard “E,” “K,” and “T” speed curves are supported plus special customizable “coordinating-speed” tap and main curves.
Superior coordination with upstream protective devices and downstream power fuses: Coordinating-speed curves provide optimal coordination on underground distribution systems.
Custom curve attributes: Coordinating-speed curves can be easily modified to include two separate definite-time delays.
Separate phase and ground curves are standard: This enables better coordination with source-side breaker trip settings. Negative sequence and sensitive earth fault protection settings are also provided.
No extra “wake-up” time: If a fault-interrupter way is closed into a fault, the fault interrupter will trip and clear the fault per the selected TCC, with no additional delay.
Self-powered: Current transformers on fault-interrupter ways provide sensing and power. No batteries or battery maintenance is needed.
Simple and straightforward programming and access to status information: All programming software is stored in the control. Programming is completed via a browser-based user interface.
Event log: The log captures information on the last 64 events captured by the control.
Diagnostic information: Data are available to assess the status of the control.
Optional external trip provisions for additional functionality: Input from external sources such as transformer sudden-pressure relays can also trip the fault interrupters.

Vista Overcurrent Control 2.0 Time-Current Characteristic (TCC) Curves

Information Bulletin 680-211 contains curve plots for all Vista Overcurrent Control 2.0 TCCs. It also contains equation parameters for E-speed, T-speed, Tap, Main, IEEE, and IEC curves.

Data points for K-speed curves can be found here.

Coordinaide™ — The S&C Protection and Coordination Assistant

Coordinaide™ lets you quickly and easily select the optimal protective device (e.g., fuses, TripSaver® II Cutout-Mounted Reclosers, Vista® Underground Distribution Switchgear, or IntelliRupter® PulseCloser® Fault Interrupters) to:

Protect transformers against damaging overcurrents and coordinate with primary- and secondary-side protective devices. See how S&C's novel Transformer Protection Index (TPI) can be used to determine if the primary fuse will protect against certain types of secondary-side faults, including arcing phase-to-ground secondary-side faults.
Protect capacitor units against case rupture.
Protect underground cables from insulation damage due to excessive temperatures.
Protect overhead conductors from damage due to annealing.
Confirm the proper operation of protective devices against incident-arc energy curves for various Personal Protective Equipment (PPE) levels.
Selectively coordinate two or more devices in series to minimize service interruptions.