Switch Disconnectors
Medium voltage indoor switch disconnectors for secondary distribution
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.
NAL
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.
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
Industries and applications:
- Industrial workshops
- Factories
- Prefabricated substations
- Compact secondary substations
- Solar and wind grid connection station
DS1
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.
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
Industries and applications:
- Utilities
- Industries
GSec & GSec Air
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.
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
Industries and applications:
- Utilities, industries
- OEM
- Panel builders
- EPCs
- End users
Product scope
| NAL | DS1 | Gsec & Gsec Air | |
| Rated voltage | up to 36 kV | up to 17.5 kV | up to 24 kV |
| Rated current | up to 1,250 A | up to 630 A | up to 630 A |
| Rated short circuit current | up 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 |
Frequently Asked Questions
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.
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.
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.
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.
Yes. ABB offers detailed Service and Maintenance instructions with extensive support for spares and accessories.
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.
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.
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.
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