Certified EEX-P Group I for tunnelling with presence of methane.
A Pressurized substation is defined as “having an internal overpressure housing EEx-pdia I 150°C”, suitable for group I conditions and classified zones.
The ATX series pressurized free substation is a free standing containerised unit, specially designed for civil engineering construction sites where there is the presence of gas. It is completely self contained and thanks to its strong structure it can operate in very severe ambient conditions.
The substation, which is painted both outside and inside is totally enclosed and is completely waterproof.
The structure is fully sealed with panels manufactured from 2.5 mm thick steel plate, reinforced as appropriate
All bolts, screws and mechanical devices have anti-corrosion treatment.
The substation is painted and finished to the following specification:
• sandblasting of all surfaces
• one coat, rust-preventative epoxy type paint, 40 micron thick
• two coats air-dried epoxy enamel, 60 micron thick, colour standard RAL 1013 white.
• non standard paint finishes are available on request
Pressurisation equipment includes:
• EEx-d housing involving electronic system for pressurisation and purging control
• EEx-i safety devices for purging and pressurisation control
• purging pneumatic system including washout valve, pneumatic on-off valve, manual register,
air rolling shutter
• holding pressure system including pressure reducer, pressure gauge and on-off valve
Pressurisation system overview
The specially designed structure allows the operator to enter the substation without any loss of pressure. This is achieved using a double stage incoming door acting as an air lock.
The pressurisation system and the cooling system are fed with dry compressed air in the pressure range 3.5 ± 7.5 bar from a standard industrial compressor.
Reducers and filters condition the air to ensure that dry and clean instrument quality air is passed into the substation
The pressurisation cycle involves first an initial purging phase of the machine at start up, followed by a permanent cycle to maintain and control the internal overpressure.
The higher pressure is utilised for the initial purging phase but during the holding phase the rate falls to 10% or less and is required only for compensating air leakage.
The working overpressure is maintained at around 2 – 5 mbar (200-500 Pa) with a low level alarm set to 0,6 mbar (60 Pa).
SIERRA II series, type tested prefabricated compact substation, suitable for secondary distribution.
No costs for on site assembly and minimal civil engineering. The small profile makes SIERRA II easy to install discretely in sensitive locations. It guarantees an high level of personal safety.
SIERRA II is totally enclosed metal cladding, self-contained and weatherproof, ready to be placed upon a concrete base pad.
The unit is typically divided into three rooms for the medium voltage switchgear, low voltage switchboard and distribution transformer.
The transformer is located in the middle of the substation while the MV and LV compartments are located at both ends of the substation adjacent to the corresponding bushings of the transformer.
The substation may be operated from the outside (Non Walk-in Accessibility Type B).
The electrical equipment is cooled by natural ventilation through openings in the substation.
The unit is mainly made of corrosion resistant 2mm AlZn-coated steel sheet. The aluminium and the zinc alloy coating provide protection against corrosion due to harsh environment conditions. In addition, 3mm galvanized steel sheets are used to make the support in the base frame (oil collection pit) stronger.
The oil collection pit, which can take 100% of the transformer’s oil volume, is integrated into the substation base frame.
Enclosure, with closed door is IP43. Doors can be fitted with gaskets in order to have degree of protection IP54.
Last finish coat is a powder paint of polymer resin base.
This compartment can be equipped with wide varieties of MV switchgear. For voltages up to 24kV, the basic configuration is a SF6 insulated RMU which consist of two load break switches and one switch-fuse combination for transformer protection, all contained in a single sealed tank. Same configuration is also available for voltages up to 36kV.
This compartment is specially designed to provide the transformer with adequate airflow cooling through well sized openings. The compartment is provided with a pressure relief system integrated in the ceiling/roof. As an option, a floor mesh can be provided to prevent entry of small animals and other foreign objects, assuring in the meanwhile continuous airflow and circulation. Oil-immersed or dry type transformers can be accommodated on this compartment.
Low Voltage Section
This compartment contains the Low Voltage Distribution Board (LVDB), which is fed from the secondary side of the transformer. The LVDB can be designed in different arrangements and configurations in order to suit any specific application. Inside the panel can be installed Air circuit breakers (ACB’s), Moulded case circuit breakers (MCCB’s), LV Fuse switches Instrumentation and metering
Natural ventilation is provided through ventilation for air intake at the bottom of the walls. The air is extracted through ventilation openings at the top of the walls, and natural air circulation ensures sufficient cooling to the distribution transformer.
As standard SIERRA II is classified and type-tested in accordance with temperature class K20. Temperature class K10 can be achieved by increasing the ventilation area for the transformer room.
The substation forms a complete metallic bolted structure. Each compartment is provided with grounding busbars. Bonding and interconnection of the grounding buses are made of 70mm2 bare stranded copper conductors.
The ring main unit (RMU) and the low voltage panel (LVDB) are provided with grounding bus that can be connected to the grounding system at site.
The SIERRA II range is designed and type-tested in accordance with EN 61330, which covers the following test programs:
Test to verify the insulation level of prefabricated substation
Test to prove the temperature rise of the main components contained in a prefabricated substation
Test to prove the capability of the earthing circuits to be subjected to rated peak and rated short-time withstand current
Functional test to prove satisfactory operation of the assembly
Test to verify the degree of protection
Test to verify the withstand of the enclosure of the prefabricated substation against mechanical stress
Additional type test in accordance with EN 61330 and PHELA Recommendation n.7 05/2004
Test to assess the effects of arcing due to internal fault.
Main components are type-tested in accordance with their individual standards:
EN 60265: High-voltage switches EN 60298: Metal-enclosed high-voltage switchgear EN 60694: High-voltage switchgear
EN 60439: Low-voltage switchgear and control gear
EN 60076: Power transformers
Compliance to other applicable Standards and Council Directives is indicated on the Declaration of Conformity draft in accordance to EN 45014 “General criteria for suppliers declaration of conformity”.
Moreover WE WALTER has adopted a quality management system for engineering, construction and testing processes compliant with the requirements of EN ISO 9001:2000.
PAK series, medium voltage electrical mobile substation for tunnelling and mining installation, is a reinforced unit, that can be installed on a truck, skid mounted or placed on a wagon, for easy handling in the tunnel.
Extremely robust and resistant to heavy mechanical stress, PAK substation can operate in extreme environmental conditions.
It conforms to European Standard IEC, Tunnelling and Mining Rules.
PAK substation is manufactured with 5 and 3 mm thick cold-worked and continuous welded steel plate.
Substation doors are mounted by inox steel hinges. Bolt, screws and mechanical devices have anti-corrosion treatment.
Enclosure, with closed door, is IP549.
Substation is painted and finished to the following specification:
sheet degreasing with synthetic thinner
sanding with scotch-brite 3M for zinc passivated steel supports
one coat antirust epoxide primer, 25 micron thick
two coats epoxide enamel, 60 micron thick
SIZE AND POWER - CLASS 12 KV
air insulated switch disconnector
(LxDxH) mm 3050 x 1650 x 950
100 ÷ 250 KVA
(LxDxH) mm 3250 x 1650 x 950
315 ÷ 630 KVA
(LxDxH) mm 3550 x 1650 x 950
800 ÷ 1000 KVA
(LxDxH) mm 4350 x 1650 x 950
100 ÷ 250 KVA
(LxDxH) mm 4550 x 1650 x 950
315 ÷ 630 KVA
(LxDxH) mm 4850 x 2000 x 950
800 ÷ 1000 KVA
SIZE AND POWER - CLASS 24 KV
gas (SF6) insulated switch disconnector
(LxDxH) mm 3350 x 2000 x 1100
100 ÷ 250 KVA
(LxDxH) mm 3550 x 2000 x 1100
315 ÷ 630 KVA
(LxDxH) mm 3850 x 2000 x 1100
800 ÷ 1000 KVA
(LxDxH) mm 4050 x 2000 x 1100
(LxDxH) mm 3850 x 2000 x 1100
100 ÷ 250 KVA
(LxDxH) mm 4250 x 2000 x 1100
315 ÷ 630 KVA
(LxDxH) mm 4350 x 2000 x 1100
800 ÷ 1000 KVA
(LxDxH) mm 4550 x 2000 x 1100
Medium Voltage Switchboard
The medium voltage switchboard is installed in a separate section segregated from the LV side, which includes:
an earthing switch disconnector on the incoming line
an on load switch disconnector with tripping coil combined with current limiting fuse (switch fuse combination)
an earthing switch disconnector on the outgoing line
To comply with current standards, different types of transformer can be provided with the substation according to customer requirements:
Cast resin transformer (50-1250 KVA)
Silicon oil transformer (50-1250 KVA)
Dry-type transformer (50-1250 KVA)
Low Voltage Switchboard
The low voltage switchboard is fitted into a separate section segregated from the MV side. It includes the main circuit breaker to protect the transformer against short circuit, overload and earth-fault.
The design arrangement of the LV utilities is manufactured to suit customer specifications and can include moulded case circuit breaker (MCCB), load break disconnector combined with current limit fuses, earth leakage protection, starters, small PLC and measuring devices as well as automatic power factor correction unit.
Pressurized substation is defined as “internal overpressure housing EEx-pdia I 150°C”, suitable for group I (coal mines with presence of firedamp) and classified area for zones C1ZO – C1Z1 – C1Z2 – C1ZR. PAK-exp series pressurized substations have been developed in two different design:
design Eex_p I (group I) for underground applications with presence of firedamp (CH4).
design Eex_p II (group II) for petrolchemical applications.
The difference between these two versions is the Eex_d box in which are installed instruments for purging and pressurization control.
Substation, painted both outside and inside is totally enclosed type and
The closed-packed structure and the panels are manufactured with 2.5 mm thick steel plate conveniently reinforced.
Bolt, screws and mechanical devices are anti-corrosion treated.
The substation is painted and finished in accordance to the following procedure:
sunblasting of the whole surface
a coat of rust-preventive paint epoxy type, thickness 40 micron
two coats of air-dry epoxy enamel, thickness 60 micron
standard RAL 1013 white.
Pressurization equipment includes:
EEx-d housing involving electronic system for pressurization and purging control
EEx-i safety devices for purging and pressurization control
purging pneumatic system including washout valve, pneumatic on-off valve, manually register, air rolling shutter
holding pressure system including pressure reducer, pressure gauge and on-off valve
Pressurization System Overview
The pressurization cycle involves firstly a purging phase at machine start up, then a permanent phase for internal overpressure holding and control.
The fluid engaged consists in dry and clean instrument air. Network pressure required is included in the range 7,5 to 3.5 bar. The biggest rate is required for the purging phase while for holding phase the rate falls till 10% or less and is engaged just for compensate eventual losses. Working overpressure is kept around 2 to 5 mbar (200-500 Pa) with alarm set on 0,6 mbar (60 Pa).
At the beginning of the purging phase, a pneumatic valve opening full rate incomes.
An EEx-i safety device for rate control pulls the time count (fixed in 30 minutes). If the rate falls under the set value, the count stops and re-starts when reset usual rate conditions.
Ending the purging phase, the holding rate is started-up by reduced pressure at 5 mbar. In the meantime purging phase stops and machine can be started.
If the internal overpressure falls under 0,6 mbar, pressure lack
If the overpressure resets within 30 min. from depressurization, it isn’t
necessary a new purging phase.
The pressurization system and the cooling system are fed by compressed dry-air, pressure 4 ± 7,5 bar. Switches working have been protected by an external door; external doors can be opened without any pressurization loss.
DESERT MV SERIES Prefabricated Substation can be used to supply quick and reliable energy in places where energy is not very accessible. DESERT MV SERIES Prefabricated Substation is a self contained and completely integrated unit designed for a specific purpose. It complies with local regulations concerning weight and dimensions for transportability and services, and for all specified conditions in respect of climate and electricity demand.
The housing of the compact substation is a totally enclosed, metal clad and weatherproof container mainly constructed using steel frames and corrugated panels welded by CO2 shielded Arc welding.
The building is typically divided in three rooms for the medium voltage switchgear, the distribution transformer and the low voltage distribution board.
The transformer is located in the middle while the M.V. and the L.V. room are located at either end of the building adjacent to the corresponding bushing of the transformer.
The substation may be operated from the inside (walk in type – Accessibility type B). Prefabricated Compact Substation in accordance to IEC/EN 61330 is classified and type-tested with temperature class K20.
Two different cooling systems will be provided – one for the transformer room (Forced ventilation) and one for the H.V. and L.V. rooms (HVAC).
The Prefabricated Substation has IP54 protection, in accordance with EN 60529.
Overall Dimensions W x D x H
ISO standard 20-30-40' or tailor made upon request
Forced Ventilation (Transformer Room)
Air Conditioned (MV and LV Room)
-5 ÷ +55ºC
5 ÷ 95%
1000 m. above sea level
Roof load withstand
Withstand wind loads
Withstand mechanical impacts
Rated System Voltage
Up to 36kV
Rated Power Installed
Up to 4MVA
This room can be equipped with wide varieties of MV switchgear. For voltages up to 36kV, the basic configuration is a SF6 insulated RMU which consists of two load break switches and one switch-fuse combination for transformer protection, all contained in a single sealed tank.
This room is specifically designed to provide the transformer, oil immersed or cast resin type, with sufficient volume of airflow for cooling through adequately sized and professionally designed ventilation openings.
Low Voltage Room
This room houses the Low Voltage Distribution Board (LVDB), which is fed from the secondary side of the transformer. The LVDB can be designed in different arrangements and configurations in order to suit any specific application.
The Prefabricated Compact Substations, Series AT-DSRT, are designed and type-tested in accordance with IEC/EN 61330 ( Standard for High-Voltage/Low-Voltage Prefabricated Substations)
Main components shall be type-tested in accordance with their individual standards:
IEC/EN 62271-200 High-voltage switchgear and controlgear Part 200: AC metal-enclosed switchgear and controlgear for rated voltages above 1 kV and up to and including 52 kV
IEC/EN EN 60439: Low-voltage switchgear and controlgear assemblies – Part 1: Type-tested and partially type-tested assemblies
IEC/EN EN 60076: Power transformers
ISO 830: Freight containers-terminology ISO 668: Series 1 freight containers-classification, external dimensions and ratings ISO 1496-1: Series 1 freight containers-specification and testing ISO 3874: Series 1 freight containers handling and securing IEC/EN 60529: Specification for degrees of protection provided by enclosures (IP code)
Compliance to other applicable Standards and European Council Directives will be indicated in the Declaration of Conformity draft in accordance to EN 45014 “General criteria for suppliers declaration of conformity”. Moreover WE Walter S.r. l. adopt a quality management system for engineering, construction and testing processes compliant with the requirements of EN ISO 9001:2000