Personnel and equipment safety are of utmost importance when designing substations or planning equipment upgrades. For hazardous areas with risks of explosion, specific electrical equipment is required to meet the level of safety necessary to protect your installations.

The Schneider Electric solutionBased on decades of field-tested experience in electrical generation and distribution for both offshore and onshore installations, Schneider Electric has adapted transformers that offer safety solutions for Zone 2 applications that are in accordance with the latest ATEX standards.With the ATEX certified, ignition-free, liquid im-mersed transformers, Schneider Electric brings a cost-effective solution that assures the highest safety standards for your personnel and equip-ment. These transformers offer you the best technology and best after-sales support with full compliance to national and international standards.

Our standard Zone 2 liquid immersed transformer is available as:• Three phase units (single phase available on

request),• Ratings up to 25 MVA, 36 kV and 50/60 Hz,• Hermetically sealed or conservator,• Ground-mounted,• Naturally cooled (ONAN) or forced air

(ONAF) on request,• With normal, low noise or very low noise

levels,These transformers are in accordance for Zone 2 applications with the latest releva norms IEC or EN.

Customer benefits• Reliable and Safe• Ignition-free• ATEX certified• Tailor-made solutions• Cost effective• Compact

Minera ATEXTransformers for hazardous areas up to 25 MVA - 36 kV

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What is a zone 2 environment?Either on-shore or off-shore, this is an area with an explosive gas atmosphere that can expect explosions though only very occasionally and when they does occur, will only last for a short period.

How do explosions occur?An explosion is any uncontrolled combustion wave. Most manufacturing and processing indus-tries generate potentially explosive atmospheres using substances ranging from solvents to baking flour. An explosion can be produced due to the combination of fuel, an oxidizer (such as the oxygen in the air) and a source of ignition energy.

What can cause ignition?Keeping in mind that every material has an Autogenous Ignition Temperature (AIT) at which it will ignite spontaneously, some of the more common ignitors are:• Accessory contacts, • Bushing live parts, • Liquid leakage, • Sparks,• Arcs,• Other electrical live parts.

What can we do to avoid ignition?• By using special “e-type” or “d-type” terminal

boxes,• By avoiding non-essential accessories, • By using ex-type plug-in bushings,• By using ex-type cable boxes and glands,• By using intrinsically safe relay.

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Areas Presence of explosive atmosphere No potential ignition source

Zone 0Continuously or for long periods or frequently

Normal operation and failure of one means of protection and two independent faults

Zone 1 OccasionallyNormal operation and frequently occuring faults

Zone 2Not likely to occur and for a short period only

Normal operation

Combustible Material

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Risk pointsDefining your precise and specific risk points before designing your transformer is of key importance. While all precautions are taken into account when dealing with Zone 2 equipment, particular attention must be paid to:• Design and assembly of each transformer

component, • HV terminals (porcelain or plug-in type bush-

ings),• HV cable box, if any,• LV terminals (porcelain bushings or bus-bar),• LV cable box,• Cable glands, gasket selection, wiring cables,

accessories, terminal boxes.For special applications which need air forced cooling, Schneider Electric can offer a set of fans with ATEX certification.

Schneider Electric’s R&D team is constantly seek-ing to find new, improved solutions to make your work areas safer for your personnel and equip-ment. Designs and accessories are in compliance with IEC 60079-0/EN50014 and IEC 60079-6/EN 50015.

Intrinsically-safe (IS) relay & terminal boxesPlacement of the IS-Relay as well as the material and design of your terminal boxes is of upmost importance for Zone 2 installations.

Depending on your voltage supply, one option is an “e-Type” terminal box for ex-proof material with a signal relay from your safe area of up to 350 meters.

As certain electrical equipment must be installed in hazardous zones, the secure option is a “d-Type” terminal box which is hermetically sealed and is capable of sustaining potential ignition sources without risk to other equipment or personnel.

Marking & documentationAll markings and documentation conform with current standards and are easy to read and identify.

Type Identification

Ex, II 3 G If ambient temp. range is different from -20 °C to +40 °CEx nACL IIB T3 (Example -20 ≤ Ta ≤ +55 °C)

Reference to accreditation (e.g.) : LCIE 05 ATEX 6029 X

Do not open when energized or do not separate when energized

Rating and marking plates : in accordance with relevant standards

Risk Points “e”- & “d”-Type terminal box

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Liquid immersed transformers Hermetically sealed or with conservator

Rated power 50 kVA - 25 MVA

Insulation level According to IEC Um = 1.1, 3.6, 7.2, 12, 17.5, 24, 36 kV

Phases 3-phase (single phase is applicable on request)

Tappings ± 2 x 2.5 % or different ranges on request

Voltage regulationWith off circuit tap changer (Regulation with on-load tap changer is available on request)

Rated frequency 50 Hz (60 Hz on request)

Vector groupsDyn11 for all rated power (other any vector group according to IEC Standards)

Material thermal class insulation According to IEC 60085 Class A

Temperature rise

Mean winding temperature rise: 65 KTop oil temperature rise: 60 KWith ambient temperature in accordance with IEC 60076-1The temperature of the cooling air should not exceed:• 20 °C yearly average • 30 °C monthly avarage of the hottest month• 40 °C at any timeFor other ambient temperatures, winding and oil temperature rise shall be adapted.

Type of coolingONAN (Oil Natural Air Natural)on request: ONAF (only transformers with radiators)

Dielectric liquidMineral oil according to IEC or ANSI standard On request: silicon, midel, vegetaloil

Ability to withstand short-circuitThe transformers are designed to withstand the thermal and dynamic effects resulting from a secondary short-circuit in accor-dance with IEC60076-5

Sound level

The measurement (A-weighed sound pressure LpA) and the cal-culation of sound level (A-weighed sound pressure level LwA) are done in accordance with IEC60076-10. The sound level require-ments are in accordance with national standards.

Installations Outdoor / Indoor

Hv & LV terminalsHV: Ex-type Plug in bushings are recommended LV: porcelaine bushings or bus-bar, housed in IP cable boxes pro-vided to prevent ignition.

Accessories

Standard: Lifting lugs, earthing terminals, rating plate, off circuit tap changer, bi-directional rollers padlocking facilities for safety purposes.For hermetically sealed transformer: pressure relief device and, on request, an intrinsically safe relay For transformer with conservator: buchholz relay and magnetic oil level indicator.

Technical characteristics

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Schneider Electric SA 35 rue Joseph Monier 92500 Rueil Malmaison France Telephone: 33-(0)-1 41 29 71 00 Fax: 33-(0)-1 41 29 71 00 www.schneider-electric.com

Minera ATEXSpecial Transformers

Document Number NRJED311023EN