Switch Disconnectors

Grid components

Switch Disconnectors

Medium voltage indoor switch disconnectors for secondary distribution

A switch disconnector can carry, interrupt and make of rated load current. Under abnormal conditions it can also carry short circuit current for a limited duration. ABB’s switch disconnectors offer high quality performance, are tested as per several international standards and can be adapted for various configurations as required by the medium voltage secondary distribution network.

ABB offers air-insulated and gas-insulated switch disconnectors up to 38.5 kV for indoor operations in medium voltage switchgear and compact substations (CSS).

  • Air-insulated switch disconnectors are suitable for cable sectionalizer, transformer and motor circuit switching. In secondary distribution substations air-insulated switch disconnectors can also be used for supplying lines, transformers and ring networks. ABB’s air-insulated switch disconnectors can be combined with DIN standard fuses for transformer protection. ABB’s ANSI version is used in metal-enclosed switchgear, pad mounted cabinets, mining and capacitor switching applications. You can read more about ABB’s ANSI switch disconnectors here.
  • Gas-insulated switch disconnectors are based on sealed for life SF6 technology (GSec) or SF6-free (GSec Air) offering high performance, reliability and long-life in a compact installation footprint.

ABB’s switch disconnectors are available for Original Equipment Manufacturers (OEM), Panel builders, EPCs (Engineering, Procurement and Construction) partners as well as end users to incorporate in their own installations or for use in repair, retrofit and upgrade projects. 

ABB supports customers and partners in staying ahead of increasing electrification needs, technology, and regulatory changes, providing the power to adapt to a rapidly evolving energy landscape.

 

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ABB’s indoor switches and disconnectors portfolio

Product scope: IEC& ANSI standards

Air-insulated switch disconnectors

NAL
DS1
NAL_NALF

TECHNICAL FEATURES

✓ Rated voltage: up to 36 kV
✓ 1,000 mechanical close-open operations



NAL: Switch disconnector for protection of distribution transformers and cables

 

NAL up to 36 kV is an indoor air-insulated medium voltage switch disconnector and switch-fuse combination. NAL offers a compact, modular design and broad functionalities with a unique design that extinguishes electric arcs and enables high switching capacity. NAL is certified as per IEC, IEEE (UL certified) and CSA standards.

NAL switch disconnector can be used in all medium voltage secondary distribution systems like industrial workshops, factories, prefabricated substations, compact secondary substations, solar and wind grid connection stations. The main areas of application of NAL switch disconnectors are: line switch disconnectors in medium voltage networks, switch disconnectors with fuses for the switching and protection of distribution transformers and motors.


Learn more here (NAL Documents)

Benefits

  • Continuous operations with 1,000 mechanical close-open operations assured and 15 years maintenance intervals. Easy to install with a modular design and full range of plug and play accessories
  • Motorized switches for network automations
  • Reliable in extreme conditions with a good performance in harsh environment (wide operating temperatures within -40/+55 Celsius degrees (higher values available based on agreement with manufacturer

Typical Applications

  • Industrial workshops
  • Factories
  • Prefabricated substations
  • Compact secondary substations
  • Solar and wind grid connection station 

 

DS1

TECHNICAL FEATURES

✓ Rated voltage: up to 17.5 kV
✓ 50,000 close-open operations



DS1: Synchronous transient-free capacitor switch

DS1, up to 17.5 kV, is the first synchronous switch isolated in dry air specifically devised and designed for capacitor banks. The perfect combination, regulated by the electronic control unit, between the semiconductors and synchronism with the network allows to increase reliability and efficiency and prolongs the life of components. It can perform up to 50,000 mechanical operations. 

Learn more here (DS1 Documents)

Benefits

  • Safe operations thanks to the DS1 integrated advanced interlocking system and absolute protection of the circuit components sensitive to overvoltage switching
  • Reduced power losses thanks to elimination of inrush reactors
  • Increased stability thanks to prestrike and restrike-free switching. Increased reliability thanks to embedded switch diagnostics and increased power quality thanks to transient-free switching 

Typical Applications

  •  Utilities 

Gas-insulated switch disconnectors

Gsec

TECHNICAL FEATURES

✓ Rated voltage: up to 24 kV
✓ SF6-free and SF6 versions available
✓ up to 5,000 close-open operations



GSec& GSec Air: High performing medium voltage three-position switch disconnector

 

GSec& GSec Air, up to 24 kV, is a medium voltage, IEC certified, indoor gas-insulated general-purpose switch disconnector with double disconnection gaps for secondary distribution. It is suitable for applications that require frequent switching and is available in a wide range of configurations. GSec and GSec Air are compliant with IEC 62271-103 (MV switches) and IEC 62271-105 (MV switch-fuse combination) standards.

GSec, based on sulfur hexafluoride (SF6), is sealed for life in accordance with IEC standard 62271-1. GSec Air is SF6-free and has dry air as the insulation medium. It has a global warming potential (GWP) of zero and is fully compliant with the EU F-gas regulation 2024/573.

GSec and GSec Air provide three positions in one structure: LINE – OPEN – EARTH. Both offerings are smart grid ready and highly flexible and suitable for line ingoing/outgoing panels, in combination with circuit breakers or with fuses.

 

Learn more here (GSec& GSec Air Documents)
Explore GSec& GSec Air Product Page

Benefits

  • It has smaller air volume (<= 25 L) and a flexible and modular design easy to integrate into existing setups and a wide range of configurations
  • Tested up to 10 openings at active load even at zero relative pressure
  • Reliable mechanical position indicator and actuator made of fully recyclable steel

 

Typical Applications

  •  Utilities, industries
  • OEM
  • Panel builders
  • EPCs
  • End users 


Product scope

Click the arrow to learn more about product scope.

 

 nal400x200DS1_400x200gsec 400x200
 NALDS1Gsec & Gsec Air
Rated voltage up to 36 kV up to 17.5 kV up to 24 kV
Rated currentup to 1,250 A up to 630 A up to 630 A
Rated short circuit currentup to 31.5 kA up to 20 kA up to 20 kA
Insulation medium Air-insulated Air-insulated GSec: Switch disconnector GSec with SF6 gas
GSec Air: Switch disconnector GSec Air with dry air
Operating mechanism Mechanical Servo Motor Mechanical
Mechanical operations 1,000 50,000 1,000
Standards IEC, IEEE (UL certified) and CSA IEC IEC

 

ANSI standards 



Guiding tool to select your switch disconnector

Do you need guidance on finding the best-suited switch disconnector? 
MV Switch Disconnector Selector

Learn More


Related offering

Secondary distribution
Air-insulated switchgear
service-retrofit-vd4-uniair400x200
Secondary vacuum circuit breakers
Sec protection relaysGC
Secondary protection relays

FAQ

1. What is a switch disconnector? 

A switch disconnector is basically a switch which, in the open position, performs isolating functions. This is addition to the function of the switch which can carry, interrupt and make rated load current. 

2. How does a switch disconnector work? 

A switch disconnector in the close position carries rated current through the main contacts (contacts of the disconnector). During interruption of the load current, the disconnector contacts open commuting the current to the interrupting chamber (in case of GSec & GSec Air, interrupting chamber is the vacuum interrupter) where interruption takes place. While closing (in case of GSec & GSec Air), the disconnector contacts make the circuit followed by the closing of the interrupting unit.  

3. What’s the difference between a vacuum circuit breaker and a switch disconnector? 

The main difference between a vacuum circuit breaker and a switch disconnector is that the circuit breaker is capable to protect the electrical circuit by clearing the fault currents. The switch disconnector instead will not interrupt the fault current, but once opened it permits to operate on the disconnected part of the plant guaranteeing the insulation from the still active part of the electrical circuit. 

4. Does ABB offer different types of switch disconnectors? 

Yes, ABB offers:  

  • air-insulated switch disconnectors suitable for cable sectionalizer, transformer and motor circuit switching, in secondary distribution substations for supplying lines, transformers and ring networks
  • gas-insulated switch disconnectors are based on sealed for life SF6 technology or SF6-free that offers high performance, reliability and long-life in a compact installation footprint.  

5. Are ABB’s switch disconnectors easy to maintain?  

Yes. ABB offers detailed Service and Maintenance instructions with extensive support for spares and accessories.

6. What are the NAL indoor air-insulated load break switches used for? 
They are designed for medium voltage applications in enclosed switchgear and compact transformer stations. They provide reliable control over overload currents and are suitable for voltages up to 36 kV and currents up to 1250 A.
7. How do the NAL switches enhance power quality and reliability?
These switches feature a high number of breaking operations at rated current value and can withstand short-circuit currents up to 31.5 kA for 1 second. They also include an earthing switch with making capacity and operate across a wide range of temperatures, ensuring consistent performance and reliability.
8. Why are NAL switches considered a safe and reliable solution?
The NAL switches offer full-range protection in combination with CEF/CEF-S current limiting fuses, ensuring safe and reliable interruption of short-circuit currents. Their design includes a visible insulating gap and meets design class 2 standards for selected types according to IEC/TS 62271-304:2008-05. 
9. How to choose between GSec and GSec Air? 

The primary difference between GSec and GSec Air is the insulation medium of the main components: 

  • GSec has SF6 (sulfur hexafluoride) gas as the insulation medium
  • GSec Air is a load breaking switch (LBS) and disconnector with dry air as the insulation medium and vacuum interrupters. GSec has a global warming potential (GWP) of 0. It is fully compliant with IEC standards and the EU F-gas regulation (EU) 2024/573

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