The need for higher reliability, more compactness and insensitivity to environmental factors are the key drivers for the evolution of SF6 gas insulated switchgear (GIS). The higher the voltage the more applicable is the use of GIS switchgear. With today’s ever-increasing land and civil cost for substations, the ability to accommodate more and more feeders in a compact space is valuable.
GIS and hybrid switchgear technology provide flexibility for substation design and commissioning. This article provides an insight into the approach followed in terms of operational features, safety and interlocks to ensure safe and reliable closed-door operation. The move towards ultra-compact switchgear without sacrificing safety and reliability is achieved by reducing the number of variables in the system prone to failure which could present danger to operation service personnel, improving the product quality, while reduction cost.
Why hybrid switchgear
SF6 gas issues
For example, TAMCO’s GV3N 36 kV hybrid GIS switchgear uses only 25% SF6 gas compared to conventional 36 kV GIS switchgear.
Hybrid SF6 switchgear
Hybrid switchgear combines the components of traditional air-insulated switchgear (AIS) and SF6 gas-insulated switchgear (GIS) technologies. It is characterised by a compact and modular design, which encompasses several different functions in one module.
Due to the introduction of vacuum technology the need for withdraw ability has come under question. This is because withdraw ability was mandatory for maintaining the breaker operating mechanism and the power path of circuit breaker. However, with the continuous evolution of superior vacuum technology there is hardly anything which can be maintained in the power path. Thus, if nothing is to be maintained then why withdraw the circuit breaker at all? This resulted in a fixed breaker design with a disconnecting switch in series performing the isolating function.
The hybrid switchgear described in this article comprises a vacuum interrupter housed inside a gas filled sealed tank. This modular approach is based on flexibility and customisability. The hybrid module can be used for extension or substitution in any traditional substation which uses an air-insulated busbar.
Hybrid GIS switchgear advantages
Safety is the primary requirement in any switchgear product design as it involves human for operation. The factors that need to be considered are:
Reliability is the second design factor that provides confidence in building reliable and uninterrupted electrical networks. The factors that provide reliability are:
As cities expand due to population growth, the availability of land becomes constrained. Hybrid panels are designed for a compact floor space without compromising safety and reliability.
The units are made of high grade, pickled in oil mild steel sheets, punched and folded on numerically controlled machines and painted by an advanced cathodic electro-deposition (CED) process which provides optimum protection against corrosion and weathering. Cubicle parts are fitted with gas sealed compartments for vacuum circuit.
The cubicle comprises two or three HV compartments and a control circuit compartment:
|2.||Disconnector and ESW indicator.|
|3.||Cable chamber access selector.|
|4.||Disconnector and ESW manual operation handle slot.|
|5.||Open/close lever for disconnector and ESW shutter.|
|7.||VCB manual operation handle slot.|
|8.||VCB shutter open/close lever for manual operation.|
|9.||Pressure gauge for GIS tank.|
|10.||VCB manual trip/close switch.|
|11.||VCB on/off indicator.|
|12.||VCB TNC switch.|
|13.||Local/remote operation selector switch.|
The above approach requires minimal consumption of SF6 gas as only VCB and DS is only in SF6 gas unlike conventional GIS switchgear where all HV compartments are in SF6. By using this approach, the SF6 consumption is reduced to 1,5 kg for up to 24 kV and 4,5 kg for 36 kV switchgear respectively. This is a strike reduction in SF6 gas consumption by up to 75% in comparison to conventional GIS.
The company’s 36 kV GIS is designed to maximise safety in installation, operation and maintenance and complies with the latest IEC standards and fitted with all mandatory interlocks as recommended by these international standards.
Features of hybrid GIS technology
Sustainability is the ability to anticipate the future and react accordingly to what will determine success. Since the product will be used as a protective device for the system as well as keeping operating and service personnel safe, the technology has aligned its growth and success to the needs of economic, environmental and social aspects in an equitable and inclusive way.
Any adverse effect on environment is minimised by the development and deployment of clean technology during the course of project. The project aimed to demonstrate the project/business growth can go hand-in-hand with an underlying commitment to the environment and society. The use of cutting-edge technology has generated multiple advantages. Hybrid GIS is a most reliable and economical solution for new installations or extensions and retrofit of existing substations minimising the faulted area and outage period in case of failure.
This article first appeared in APT’s Transmission & Distribution magazine and is republished here with permission.
Contact Coert Scholtz, Malaysian Switchgear, Tel 011 298-1800, email@example.com
Source: EE plublishers