Prefabrication of Ex-type Energy Distribution Switchgears for Containers Located in Explosion Hazard Zones

Donat Czapski

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  • selection of the optimal (economically and technically justified) solution for the actual installation conditions (explosion hazard zones) of the equipment
  • production in a reasonably short period of time with the possibility of introducing presumable changes during the project implementation


  • pre-design consultation aimed at selecting an appropriate solution
  • development of switchgear designs in accordance with the design and engineering specifications
  • prefabrication of five Ex-type switchgears configured to individual customer orders, carried out in our own assembly plant (we hold the “Certified Assembly Partner for Explosion Protected Products” certificate which gives us the necessary authorisations to build switchgears for the 1st or 21st explosion hazard zone)

In the chemical, mining and related industries, stand-alone containers are often used for the installation of measuring and control equipment. These containers are often located in the area of process installations where there is a risk of explosion of gases, dusts or mists and vapours of flammable liquids. Therefore, they should be adapted to operation in potentially explosive atmospheres, taking into account the actual installation conditions. Their equipment, e.g. lighting or electric armour, should be manufactured in accordance with the requirements of the ATEX Directive.

Our long-term client that implements a number of projects in the field of automation and power engineering for the industry commissioned us to prepare an executive design and prefabrication of five electrical switchboards in the Ex design.

Prefabrication of energy distribution switchgears for use in potentially explosive atmospheres – from concept to implementation

Operating within the quality assurance system, while maintaining uniform production procedures, evaluation criteria, test methodology and reporting principles, having qualified staff with appropriate knowledge, skills and experience and having a properly equipped machine park, as well as access to the parts and components warehouse, we were able to plan the course of work and start to carry out the order according to the individual needs of our client.

When starting the project, we thoroughly familiarized ourselves with the technical documentation that we received from the client. Then we started to work on the detailed design, one of the necessary elements of which was the calculation of power losses emitted inside the switchgear, related to electrical devices and components installed therein. The correct calculation of the losses guarantees safe operation of switchgears in a specific explosion hazard zone.

Verification of technical requirements at the pre-design stage allowed the selection of optimal solutions, which in turn determined the selection of specific components and the final material specification. The choice of the appropriate type of explosion protection was based on an in-depth analysis which was to justify its use from the engineering and economic point of view.

In the case in question, the best solution was to use switchgears of reinforced structure (Ex-e) and appropriate overcurrent protection, differential current protection and contactors in the Ex-ed design. This also applied to multifunctional relays, ensuring functionality adequate for the given process and the components used which guaranteed safe use of switchgears in the explosion hazard zone.

In addition to the executive design and prefabrication of five switchgears, the contract included the performance of functional tests and the preparation of as-built documentation.

Own prefabrication of Ex equipment – a way to meet individual customer needs

Knowledge of devices operating in explosion hazard zones and experience in their prefabrication enabled us to successfully implement the project. This way, we were able to offer solutions that met individual customer requirements. Prefabrication took place in our production plant, which facilitated effective response to the current needs of the customer, e.g. in terms of additional functionality of the switchgear (including installation of additional circuits in the switchgear or supplementary equipment). From our point of view, it was also important to be able to control every stage of production.

An unquestionable advantage that allowed us to start the implementation of the order was the fact that we are among a few companies in Poland that are entitled to produce power distribution switchgears intended for operation in zone 1 or 21 of explosion hazard.

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