Transformers for hazardous areas require specialized engineering, surface temperature control, and Ex certification. BRASCOELMA offers certified dry-type transformers for these applications.
In a refinery, chemical plant, fuel terminal, industrial processing facility, or grain processing operation, electrical safety takes on an entirely different dimension.
A spark can become an ignition source. However, that is not the only risk.
A surface heated beyond acceptable limits can also reach temperatures capable of igniting certain gases, vapors, or combustible dust.
For this reason, transformers installed in hazardous classified areas cannot be specified as conventional electrical equipment.
It is essential to understand the area’s classification, the atmosphere present, the allowable temperature, the required protection level, and actual operating conditions.
BRASCOELMA develops custom-engineered, three-phase dry-type transformers for hazardous classified areas, certified for applications in potentially explosive atmospheres.
WHAT IS AN EXPLOSIVE ATMOSPHERE?
An explosive atmosphere occurs when flammable substances in the form of gases, vapors, dust, fibers, or suspended combustible materials mix with air under conditions capable of sustaining combustion propagation following ignition.
For an explosion to occur, three elements must coexist:
fuel + oxygen + ignition source.
Because oxygen is naturally present in the air, controlling potential ignition sources becomes essential.
And an ignition source does not necessarily mean a spark.
The surface of electrical equipment itself can reach temperatures high enough to ignite the surrounding atmosphere.
This is precisely why specifying electrical equipment for these environments requires additional safety criteria.
WHAT IS A HAZARDOUS CLASSIFIED AREA?
A hazardous classified area is a location where an explosive atmosphere is present or may be present in sufficient quantities to require special precautions in the construction, installation, and use of electrical equipment.
Area classification must not be based on perception or assumptions.
It considers the probability and duration of an explosive atmosphere being present and typically involves professionals from different disciplines, including:
- Design engineering;
- Maintenance;
- Process engineering;
- Operations;
- Industrial safety;
- Ex specialists.
This assessment is the starting point for properly specifying a transformer intended for the location.
WHAT DO ZONES 0, 1, 2, 20, 21, AND 22 MEAN?
Zones indicate the expected frequency and duration of an explosive atmosphere.
| ZONE | ATMOSPHERE | PRESENCE OF AN EXPLOSIVE ATMOSPHERE |
|---|---|---|
| Zone 0 | Gas | Continuously, frequently, or for long periods |
| Zone 1 | Gas | Occasionally during normal operation |
| Zone 2 | Gas | Unlikely during normal operation; if present, only for a short period |
| Zone 20 | Dust | Continuously, frequently, or for long periods |
| Zone 21 | Dust | Occasionally during normal operation |
| Zone 22 | Dust | Unlikely during normal operation; if present, only for a short period |
Equipment certified for a more demanding zone may also be suitable for less demanding zones under the corresponding conditions. For example, equipment suitable for Zone 1 may also meet Zone 2 requirements.
WHAT DO EQUIPMENT GROUPS I, II, AND III MEAN?
In addition to the zone, the type of atmosphere must be identified.
Equipment is classified into groups:
Group I: Coal mines subject to firedamp or methane.
Group II: Gas atmospheres, subdivided into IIA, IIB, and IIC.
Group III: Dust atmospheres, subdivided into IIIA, IIIB, and IIIC.
For Group II, examples include:
IIA — Propane
IIB — Ethylene
IIC — Hydrogen
For Group III:
IIIA — Combustible fibers
IIIB — Non-conductive dust
IIIC — Conductive dust
This information directly affects the specification of Ex equipment.
WHAT IS A TEMPERATURE CLASS IN HAZARDOUS AREAS?
The temperature class establishes the maximum surface temperature that equipment may reach during operation under the specified conditions.
Temperature classes range from T1 to T6.
The higher the T classification number, the lower the maximum permitted surface temperature.
For example, T6 equipment has a maximum surface temperature of 85°C (185°F) and may be suitable for areas requiring T5, T4, T3, T2, or T1.
The required temperature class is determined by considering the gas or dust with the lowest ignition temperature present at the location.
This explains why the thermal design of a transformer intended for a hazardous area is just as important as its electrical design.
WHAT IS EPL?
EPL — Equipment Protection Level expresses the likelihood of a particular piece of equipment becoming an ignition source.
For gas atmospheres, the classifications are:
Ga / Gb / Gc
For dust atmospheres:
Da / Db / Dc
These classifications correspond respectively to Zones 0/1/2 and 20/21/22.
Therefore, zone, group, temperature class, and EPL must be interpreted together.
WHAT ARE THE MAIN TYPES OF EX PROTECTION?
Ex protection refers to construction measures designed to prevent electrical equipment from igniting the surrounding explosive atmosphere.
Relevant protection types include:
Ex d — Flameproof enclosure: Components capable of causing ignition are contained within an enclosure designed to withstand an internal explosion without allowing it to propagate.
Ex e — Increased safety: Uses measures designed to prevent arcs, sparks, or excessive temperatures during normal operation.
Ex n — Non-sparking protection: Used in Zone 2 applications to prevent equipment from causing ignition during normal operation.
Ex m — Encapsulation: Critical components are protected by insulating resin.
Ex t — Protection by enclosure: Used for dust atmospheres, preventing dust ingress and limiting surface temperatures.
Ex p — Pressurization: Uses positive internal pressure to prevent an explosive atmosphere from entering the enclosure.
The appropriate protection method depends on the specific characteristics of each installation.
DO TRANSFORMERS FOR HAZARDOUS AREAS REQUIRE CERTIFICATION IN BRAZIL?
Yes.
Equipment intended for potentially explosive atmospheres is subject to mandatory certification.
The Ex Certificate of Conformity is issued by a Product Certification Body (OCP) accredited by INMETRO, demonstrating compliance with the specific requirements of applicable standards.
This means that a manufacturer’s declaration that its equipment is suitable for a particular hazardous area is not sufficient.
Compliance must be demonstrated through the applicable certification system.
WHAT CERTIFICATION DOES BRASCOELMA HOLD FOR HAZARDOUS-AREA TRANSFORMERS?
BRASCOELMA holds Ex Certificate of Conformity IEx 23.0254X for its dry-type transformers intended for hazardous classified areas.
The certification marking is:
Ex eb IIB T3 Gb
The certificate was issued by OCP-0064, accredited by INMETRO.
The certification demonstrates that the design, materials, manufacturing, and testing were subjected to third-party assessment in accordance with the applicable requirements of the ABNT NBR IEC 60079 series.
There is also an important detail at the end of the certificate identification:
The suffix “X” indicates that the complete Ex equipment has specific conditions of use that must be observed during installation and operation.
WHAT DOES THE MARKING EX EB IIB T3 GB MEAN?
Each element of the marking provides important information about the equipment’s intended application.
Ex: Equipment intended for potentially explosive atmospheres.
eb: Increased safety protection at the level specified by the certification.
IIB: Gas group covered by the certification.
T3: Equipment temperature class.
Gb: Equipment Protection Level for gas atmospheres.
This marking must not be interpreted in isolation.
Compatibility with the installation must be confirmed based on the actual hazardous-area classification and the project’s specific conditions.
HOW DOES BRASCOELMA DESIGN A TRANSFORMER FOR A HAZARDOUS AREA?
The design process begins before the first drawing is created.
First, the engineering team gathers the following information from the customer:
- Power rating;
- Input voltage;
- Output voltage;
- Zone;
- Group;
- Temperature class;
- Environmental conditions;
- IP protection rating.
This information establishes the equipment’s basic requirements and allows the electrical design to be aligned with the location’s safety conditions.
In other words:
First, understand the application. Then, design the transformer.
HOW ARE ELECTRICAL AND THERMAL REQUIREMENTS CALCULATED?
The design includes sizing the magnetic core and windings, considering electrical and thermal characteristics simultaneously.
One objective is to ensure that the surface temperature remains within the temperature class required for the application.
Additionally, the design may include:
- Primary winding taps;
- Input and output terminal boxes;
- Certified cable glands;
- An enclosure compatible with environmental conditions;
- Appropriate surface finishing;
- A nameplate displaying the complete Ex marking.
This demonstrates why an Ex transformer is not simply a conventional transformer installed in a hazardous location.
WHAT ARE TRANSFORMER TAPS USED FOR?
Transformer taps allow adjustments to the output voltage when the supply voltage is above or below the nominal design value.
In BRASCOELMA equipment, these taps are located on the primary winding.
However, changing tap settings requires a specific procedure.
The equipment must be de-energized, the absence of voltage at the terminals must be confirmed, and the adjustment must be performed on all three phases.
Additionally, initial startup must be performed using the nominal tap setting.
WHY MUST CABLE GLANDS ALSO BE CONSIDERED?
Because installation safety extends beyond the transformer itself.
The input and output terminal boxes use certified cable glands, sized according to the cables specified in coordination with the customer.
This illustrates an essential principle of Ex installations:
Compliance depends on the complete assembly.
Certified equipment that is installed incorrectly or combined with unsuitable components can compromise the safety intended by the design.
HOW ARE TRANSFORMERS TESTED BEFORE DELIVERY?
Each unit is manufactured according to the certified design and undergoes routine testing before release.
Recorded checks include:
- Input voltage;
- Output voltage;
- Current in each phase;
- Transformation ratio;
- Tap operation.
The results are documented in a test report delivered with the equipment documentation.
This means customers receive not only the transformer but also technical records associated with the manufactured unit.
WHAT DOCUMENTATION ACCOMPANIES THE TRANSFORMER?
Each transformer is supplied with an equipment-specific instruction manual.
The documentation includes:
- Photographs of the manufactured equipment;
- Technical data sheet;
- Installation instructions;
- Input and output cable specifications;
- Test and measurement report;
- Maintenance and care instructions;
- Tap-changing procedure;
- Dimensional drawing;
- Nameplate drawing;
- Copy of the Ex Certificate of Conformity;
- Warranty statement.
In an Ex installation, documentation is not merely an accessory.
It is part of traceability and proper equipment management throughout its operating life.
DOES SAFETY END ONCE THE TRANSFORMER IS INSTALLED?
No.
Ex equipment must remain in safe operating condition throughout its service life.
Therefore, installation must follow applicable requirements, and inspections must continue after the equipment is commissioned.
The guidelines include installation in accordance with ABNT NBR IEC 60079-14 and periodic inspections according to ABNT NBR IEC 60079-17.
Additionally, during the first month of operation, electrical connections and cable glands should be checked and retightened when necessary.
WHAT SHOULD BE MONITORED DURING OPERATION?
Current and voltage should be recorded periodically and compared with values considered normal for the application.
Deviations in:
current, voltage, or temperature
may indicate that the system requires inspection.
Additionally, acquisition, installation, and maintenance documentation must remain organized.
In hazardous classified areas, maintenance history and traceability are also part of compliance management.
DO DRY-TYPE TRANSFORMERS FOR HAZARDOUS AREAS REQUIRE EXTENSIVE MAINTENANCE?
The mechanically simple construction of dry-type transformers results in low maintenance requirements, making this configuration a robust, low-operating-cost solution for hazardous classified areas under the specified conditions.
However, this does not mean “maintenance-free.”
Connections, electrical conditions, temperature, equipment integrity, and associated installation components must continue to be inspected.
In Ex environments, proper maintenance is also a matter of safety.
WHERE CAN DRY-TYPE TRANSFORMERS FOR HAZARDOUS AREAS BE USED?
Applications include industrial environments where gases, vapors, or combustible dust may create potentially explosive atmospheres, such as:
- Oil refineries and offshore platforms;
- Chemical and petrochemical plants;
- Gas and fuel terminals, pipelines, and distribution facilities;
- Sugar and ethanol plants;
- Grain handling and storage facilities;
- Paint and varnish manufacturing;
- Paper manufacturing;
- Textile manufacturing;
- Wastewater treatment plants.
However, each environment must be properly classified before equipment is specified.
WHY SHOULDN’T A HAZARDOUS-AREA TRANSFORMER BE PURCHASED BASED SOLELY ON KVA?
Because power rating is only one part of the specification.
Consider two transformers with the same rated capacity.
One will be installed in a conventional industrial environment.
The other will operate in a classified atmosphere where flammable gas may be present.
Electrically, certain characteristics may appear similar.
From a safety perspective, these are completely different applications.
For hazardous areas, engineering must consider:
power + voltage + zone + group + temperature class + EPL + Ex protection + IP rating + environment + installation.
Together, these factors determine whether the equipment is compatible with the application.
WHAT IS THE MOST DANGEROUS SPECIFICATION MISTAKE?
Treating the term “hazardous classified area” as a complete specification.
It is not.
Simply stating that a transformer will be installed in a hazardous classified area leaves essential questions unanswered:
Which zone?
Which group?
Which temperature class?
What atmosphere is present?
What EPL is required?
What degree of protection is necessary?
What are the environmental conditions?
For this reason, the design process begins with the complete classification of the installation, not equipment selection.
CHECKLIST: WHAT INFORMATION IS REQUIRED TO SPECIFY AN EX TRANSFORMER?
Before requesting a project, gather:
- Required power rating;
- Input voltage;
- Output voltage;
- Frequency;
- Three-phase configuration requirements;
- Hazardous-area classification;
- Zone;
- Group;
- Temperature class;
- Required EPL;
- IP protection rating;
- Environmental conditions;
- Cable characteristics;
- Electrical load to be supplied;
- Installation-specific requirements.
The more complete the information, the more accurate the equipment specification can be.
FAQ — DRY-TYPE TRANSFORMERS FOR HAZARDOUS AREAS
WHAT IS A TRANSFORMER FOR A HAZARDOUS AREA?
It is a transformer designed to operate in locations where an explosive atmosphere is present or may develop, requiring special protective measures.
DOES BRASCOELMA OFFER CERTIFIED TRANSFORMERS FOR HAZARDOUS AREAS?
Yes. BRASCOELMA holds Ex Certificate of Conformity IEx 23.0254X, with marking Ex eb IIB T3 Gb, for its dry-type transformers intended for the conditions covered by the certification.
WHAT DOES THE “X” IN THE CERTIFICATE MEAN?
The suffix X indicates that the complete Ex equipment has specific conditions of use that must be observed during installation and operation.
MUST A TRANSFORMER FOR A HAZARDOUS AREA BE CERTIFIED?
Yes. Equipment intended for potentially explosive atmospheres is subject to applicable mandatory certification requirements in Brazil.
WHAT DOES T3 MEAN?
T3 is a temperature class. The classification relates to the maximum permitted equipment surface temperature under the certified operating conditions.
WHAT DOES IIB MEAN?
IIB identifies a subgroup of equipment intended for certain gas atmospheres. Ethylene is used as a reference for this group.
WHAT INFORMATION DO I NEED TO REQUEST A TRANSFORMER?
Essential information includes power rating, input and output voltages, hazardous-area classification, zone, group, temperature class, environmental conditions, and the required degree of protection.
IS THE TRANSFORMER TESTED BEFORE DELIVERY?
Yes. Each unit undergoes routine testing, and the corresponding test report is included in the documentation delivered to the customer.
DO DRY-TYPE TRANSFORMERS REQUIRE MAINTENANCE?
Yes. Although their mechanically simple construction results in low maintenance requirements, periodic inspections and checks remain necessary.
IN WHICH INDUSTRIES CAN THIS SOLUTION BE USED?
Applications include oil and gas, chemical and petrochemical, sugar and ethanol, grain storage, paints and varnishes, paper, textiles, and wastewater treatment.
IN A HAZARDOUS AREA, IT IS NOT ENOUGH FOR THE TRANSFORMER TO WORK. IT MUST BE SUITABLE FOR THE ATMOSPHERE IN WHICH IT OPERATES.
Designing a transformer for a potentially explosive atmosphere involves far more than calculating voltage, current, and power.
The area’s classification must be understood.
Appropriate protection must be selected.
Surface temperature must be controlled.
Compatible components must be used.
Manufacturing must follow the certified design.
Testing must be performed.
Documentation must be provided.
And safe operating conditions must be maintained throughout installation, operation, and maintenance.
BRASCOELMA combines engineering, manufacturing, and certification to develop custom dry-type transformers for applications covered by its Ex certification.
Does your industrial facility need a transformer specified for a hazardous classified area? Contact BRASCOELMA’s engineering team and provide the electrical specifications and complete hazardous-area classification of your installation.