ATX SERIES Pressurized Substation

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.

Construction

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.

Painting

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 devices

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).

Size and power ATX Series

Series ATX65L.*** (250-800kVA)

Overall dim. (LxDxH) mm 7310 x 2400 x 2590

Series ATX95L.*** (250-800kVA)

Overall dim. (LxDxH) mm 10310 x 2400 x 2590

TECHNICAL DATA FOR 24kV
Rated voltageKV24
Insulation levelKV50
Impulse insulation levelKV125
Rated frequencyHz50-60
Rated secondary voltageVup to 1000
Transformer CapacityKVA800
Fixed P.F.C.U.kVARup to 30
Automatic P.F.C.U.kVARup to 300
Auxiliary voltageVac/Vdc230/24 230
Enclosure (ingress protection degree)IP549 - IPH6
Operating ambient temperature-10 / +40ºC
Humidity (non condensing)Rh 85%
Altitude1000 m a.s.l.