SF6-free RMUs | BGS-40.5
Medium voltage rmus for 40.5kV applications (summary)
BGS-40.5 stands for Brunstock Gas insulated Secondary switchgear, rated up to 40.5kV. This ring main unit utilises vacuum switching and SF6-free sealing technology. The main circuit and high-voltage components are sealed in the gas tank, making it suitable for operation in remote sites with harsh environmental conditions, including heat, cold, humidity, salinity, dust and even at high altitude.
This ring main unit is just 600mm x 1000mm, a compact footprint that makes it a flexible solution which can be widely applied. You will find it in all kinds of substation kiosks in renewable project sites like wind and solar farms, in power utility applications, and at airports and railways.
Application
BGS-40.5 is one of our SF6-free gas insulated switchgear series, which supports project sustainability by ensuring no harmful greenhouse gases will ever leak from your GIS.
These RMUs are custom designed solutions that suit a wide range of industries, including renewables; utilities; infrastructure; mining, oil and gas. Brunstock engages its wide network of experts in electrical engineering to manufacture cutting-edge power technology.
Why choose dry air to insulate your switchgear
Better than SF6
Using compressed dry air instead of SF6 (sulfur hexafluoride) in secondary switchgear rmus offers many benefits. Dry air is an environmentally friendly alternative because it is a natural and non-toxic gas with a significantly lower global warming potential compared to SF6, which has a high greenhouse effect. Additionally, dry air is less expensive and more readily available than SF6, making it a cost-effective choice for many applications. It also means you will not have to deal with handling and disposing of SF6.
Better than nitrogen
Some competing switchgear use pure nitrogen technology to remove the environmental impact of SF6. Using dry air instead of nitrogen (N2) in secondary switchgear can offer several distinct advantages. Firstly, dry air, being a mixture of nitrogen and oxygen, provides a more natural and stable insulating medium that can effectively support high-voltage applications while being less prone to issues related to partial discharge and dielectric breakdown compared to pure nitrogen.
Additionally, dry air is more readily available and often less expensive than pure nitrogen, which can lead to cost savings in terms of both procurement and system operation. Moreover, dry air, when properly conditioned to maintain low humidity, helps prevent the formation of condensation and corrosion within switchgear components, enhancing the overall reliability and lifespan of the power equipment.
Using dry air also avoids the need for the specialised handling and storage protocols required for high-purity nitrogen, simplifying maintenance and operation.
It won’t cost more
Brunstock is offering SF6-free equipment that equates to or undercuts the SF6 competition. Can’t believe it, until you see it? Get in contact with your Brunstock rep to find out more.
About Brunstock
As an innovator in the energy industry, Brunstock represents environmentally friendly electric power system technologies. Led by a team of global power grid experts, Brunstock brings new technology to the world’s energy systems. Our range includes innovative green substation products: ester oil transformers, SF6-free RMUs and SF6-free primary GIS.
Benefits of BGS-40.5
- Environmentally friendly
- Cost efficient
- Maintenance free
- Safe and reliable
- Compact
- Operation continuity
- Fast delivery
Features
- Type tested according to IEC62271-100, IEC62271-200
- Metal enclosed, partition class PM
- Loss of service continuity category: LSC2B
- Protection index: Gas tank IP67, enclosure IP4X
- Mechanical endurance: circuit breaker 20,000, three-position disconnector/earthing switch 3000
BGS-40.5 rmus technical data
| Type | Measure | Description |
|---|---|---|
| Rated voltage | kV | 40.5 |
| Rated main busbar current | A | 1250 |
| Rated circuit breaker current | A | 630, 1250 |
| Power frequency withstand voltage | kV (1 min) | 95 |
| Lightning impulse voltage | kV peak | 185 |
| Short-time withstand current | kA/s | 31.5/4 |
| Peak withstand current (50Hz) | kA | 80 |
| Rated filling pressure at 20°C | MPa | 0.13 |
| Gas leakage | %/year | ≤0.01 |
| Rated operating sequence | | O-0.3s-CO-180s-CO |
| Internal arc classifcation | kA/s | AFLR 31.5/1 |
| Partial discharge (interval) | pC | ≤20 @ 1.1 Ur |
Environmental conditions these rmus can withstand
| Type | Measure | Description |
|---|---|---|
| Ambient temperature | °C | -25 to +40 * |
| Altitude | m | ≤3,000 above sea level * |
| Relative humidity | % | Daily average ≤98 |
* Note: for further ambient temperature range or higher altitude, please consult your Brunstock representative.
Dimensions
| Width | 600mm |
| Depth | 1000mm |
| Height | 2250mm |
BGS-40.5, a versatile switchboard rmu
BGS-40.5 is a medium voltage gas insulated switchboard up to 40.5kV, 1250A, 31.5kA, 4s. It is used in secondary power distribution and is designed for
customised application of switchgear in:
- Compact secondary substations
- Industrial zones
- Renewable power plants (BESS, wind, solar etc.)
- Hotels, shopping centres, office buildings, business centres etc.
Electrically insulated using SF6-free gas
Using dry air instead of SF6 (sulfur hexafluoride) in secondary switchgear offers several key benefits. Dry air is an environmentally friendly, natural and non-toxic gas alternative to SF6, which poses a much higher global warming risk should the gas escape. Compressed dry air is less expensive and more readily available than SF6, making it a cost-effective choice for the applications in which Brunstock recommends using it. Dry air removes the challenge of handling and disposing of SF6.
Compact
The design of BGS-40.5 makes it one of the most compact medium voltage (MV) switchboards available for substation projects.
Simple operation and maintenance
With a service life of 30 years for the main circuit, without maintenance, the overall design of BGS-40.5 guarantees simple and reliable use:
- Simplified maintenance of the functional units combined with continuity of service for the other units (LSC2 class)
- No gas filling is required on site at installation nor during the service life of BGS-40.5 under normal operating conditions
- Long service life
- Interlocking to ensure the correct sequences of operations
- Can be used in substations with or without walk-in operation corridors
- Voltage presence indicator light
- Wide cable compartment to allow the installation of various types of cable
Safety and innovation
BGS-40.5 was designed for maximum safety of the operators and equipment. In case of internal arcing in the equipment it features:
- Safety valves at the rear yield, which will avoid gas overpressure;
- An exhaust duct that evacuates the gases towards the top (optional) and/or a deflector at the rear channels that cools the hot gases; and
- Full protection for operators.
Resilient
BGS-40.5 is insensitive to the outside environment and is resilient to:
- Humidity
- Dust
- Pollution
- Dirt
- Pests, such as rodents
Operating conditions
- Altitude: ≤3000m
- Ambient temperature: -40°C ~ + 40°C
- Relative humidity: ≤95% (daily), ≤90% (monthly)
- Seismic intensity: ≤grade 8
Note: if a deviation from normal service conditions occurs, the customer can negotiate with their Brunstock representative.
Index Protection (IP)
- Main electrical circuits: IP67
- Operating mechanisms: IP4X
- Cable connection compartment: IP2XC
- Switchgear: IK07
Partition class and loss of service continuity category
- Partition Class: PM
- Loss of Service Continuity Category: LSC2A
Internal arc classification
BGS-40.5 is a pressurised sealed-unit system that complies with IEC 62271-1. Internal arc classification as per IEC 62271-200 is detailed in the table to the left. In the unlikely event of gas overpressure, the gas is discharged via safety valves away from the operator.
- PM class according to IEC 62271-200 edition 2: metallic partitioning between compartments;
- Based on IEC62271-200 edition 2, this RMU is classified as LSC2A.
These rmu switchboards comply with the standards.
IAC (internal arc classification): The metal enclosed switchgear may have different types of accessibility on the various sides of its enclosure.
To identify the different sides of the enclosure, the following codes will be used (according to IEC 62271-200 standard).
A: restricted access to authorised personnel only F: access to the front side L: access to the lateral side R: access to the rear side LSC2A (loss of service continuity): this category defines the possibility to keeping other compartments energised when opening a main circuit compartment.
RMU BGS-40.5 components
BGS-40.5, (Brunstock Gas-insulated Secondary switchgear rated to 40.5kV, is a composite apparatus that has all the main circuit switches sealed in a metal enclosure. The insulation medium is dry air, making it an SF6-free green GIS. Suitable for Ring Main Units (RMUs) and dual power supplies in 40.5 kV networks, it allows for a transition from traditional single power supply systems.
BGS-40.5 is especially suitable for industrial and commercial zones or rural areas, which have high-density power supply loads and use a cable feed network. This switchgear has the advantages of safe operation in any weather, easy installation, little maintenance and the conservation of space. It is ideal for installation in substations and wind driven generators. The RMU can be flexibly combined by the extension of busbars.
BGS-40.5 is supplied with the following standard equipment
- Vacuum circuit breaker
- Earthing switch with single spring operating mechanism
- Switch position indication for circuit breaker, disconnector and earthing switch
- Single spring operating mechanism on cable switches
- Two-position mechanism with auto-reclosing duty for vacuum circuit breaker
- Cable bushings horizontal in front or vertical at the bottom, with integrated voltage divider for voltage indication
- Busbars, 630A/1250A
- Earthing bar
- Operating handle
- Lifting lugs for easy handling
- Adjustable cable support bars
Service conditions
- Altitude: ≤3000m
- Ambient temperature: -40°C ~ + 40°C
- Relative humidity: ≤95% (daily), ≤90% (monthly)
- Seismic intensity: ≤8°
Note: if a deviation from normal service conditions leads to any problems, the customer can discuss them with their Brunstock representative.
RMU technical characteristics
- Equipped with circuit breaker function unit
- Small volume, lightweight, the single minimum volume is 600 x 1000 x 1900mm, which is suitable for the use case in renewables and in energy storage systems (height with LV compartment is 2250mm)
- Easy operation, safe use, convenient maintenance—the switchgear can be used for 30 years without maintenance
- This RMU is designed to be omniseal, without exposed live parts, and can run for a long time in an adverse environment
- If necessary, the gas tank can also adhere to IP67, making it suitable for high salt fog areas, such as a maritime wind farm
40.5 kV secondary SF6-free RMU
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