Currently, environmentally friendly vegetable oil has been applied to high-voltage 220/550kV transformers, achieving good electrical performance and environmental performance. The American box variable seals the switch, transformer and other high-voltage circuits inside the oil tank, which has a compact structure, and can be environmentally friendly and safe through the use of vegetable oil substitution. Realise SF6-free substitution of box transformers.
The medium voltage underground distribution station has evolved from a complex structure to a small, compact unit.
The evolution of the technology is described below:
The two-storey civil building on the first floor accommodates the introduced overhead lines. The ground floor houses the individual air switches, protection devices, transformers and low voltage units.
A one-storey civil engineering building accommodates the introduced underground lines located in the common areas. The building houses individual metal-enclosed air brake switches and protection units connected to an oil-filled transformer.
Prefabricated structure housing the introduced underground lines located in the common areas. Separate prefabricated metal modular switching and protection compartments connected to silicone or oil-filled transformers.
The integrated distribution substation combines switching, protection, and modification in a non-toxic, biodegradable, high fire point, Class K fluid medium. The equipment does not require civil structures.
The design offers the following advantages:
- Easy installation
- Superior transformer protection
- Improved safety
- Increased reliability
- Environmentally friendly
- SF6-free
- High fire point Class K fluids
Millions of pad-mounted compact distribution substations have been installed in the Americas and other countries over the past 40 years. The design complies with the American National Standard (ANSI®), which contains strict guidelines to ensure operation and enclosure integrity.
Fully shielded submersible connections for indoor and outdoor applications
- Built-in electrical stress control
- Moulded EPDM rubber construction for freedom from contamination
- Built-in capacitance test points to easily check circuit status
- Rotates to three positions to select alternate source, open and ground
- Silver plated copper contacts
Load switch unit
- Shielded, non-resistive design for use with liquid-filled equipment
- Includes shielding to control electrical stress with ground plates
- Suitable for indoor or outdoor applications
Vegetable oils offer the best safety and environmental options compared to mineral oils
- Fully biodegradable, seed-based, non-toxic fluids
- Class K, high fire and flash points
- Extends insulating paper life by 5 to 8 times
- UL® classified and FM Global® certified
- Fluid-immersed parts are Envirotemp® FR3™ fluid tested and certified
- Dielectric strength = 56 kV
- Ignition point = 360°C
- Flash point = 330°C
Cost Savings
- Minimum real estate required
- Minimum civil works required for outdoor applications (no buildings or vaulted structures)
- Integrated single enclosure from the same manufacturer – no need to buy and store three separate components
- Lowest installation costs
- Reduced external wiring and connectors
- Envirotemp®FR3™ less flammable fluid allows indoor installation without sprinklers or vaults
Safety
- Envirotemp FR3 Class K Fluid Essentially Eliminates Hazard of Transformer Pool Fires
- Magnex® circuit breaker is an overcurrent protection device that also senses high fluid temperatures
- Deadfront with shielded connectors eliminates flashover
- Capable of operating in flood conditions
- Integrated enclosure compartment design allows access to authorised personnel only
Environmental benefits
- No SF6
- Eliminates ozone-depleting SF6 gas used in RMU switching modules
- Elimination of SF6 arc by-products
- 1997 Kyoto Protocol – Developed countries agreed to reduce total greenhouse gas emissions, including SF6, by 5.2% over the period 2008-2012
- Fluid charging equipment will help achieve this goal
- Envirotemp FR3 fluid is a renewable seed oil that is non-toxic and biodegradable
- Low profile design blends in with the environment
Operational integrity
- Envirotemp FR3 fluid extends the thermal life of the insulation paper and increases overload capacity
- Components are assembled and tested as a unit under the fluid at the factory
- Reduced load loss due to elimination of cables and connections for each component