Explosion-proof Ex connectors – types and basic principles of operation and maintenance

Explosion-proof connectors are one of the many groups of devices included in the electrical equipment, which are certified and approved for use in potentially explosive atmospheres. This means that they have a similar protective role to terminal boxes or control cassettes. Their main task is to prevent the emergence of a potential ignition source of an explosive atmosphere, mainly by eliminating sparks, the risk of electrostatic discharge or the possibility of overheating.

Basic types of Ex explosion-proof connectors: plugs and sockets

When discussing the basic principles related to the operation and maintenance of explosion-proof connectors, it is useful to first identify the types of Ex connectors we may encounter in production spaces. Most commonly, you will encounter explosion-proof plugs and sockets. These types of connectors are commonly found from manufacturing companies that process combustible and explosive dust, through the oil, gas, chemical or petrochemical industries, where there are mainly gaseous explosive atmospheres, to complex offshore installations and offshore platforms that operate in very harsh atmospheres in addition to gas zones 1, 2.

The receptacles can be mounted either on walls and other flat surfaces (wall mounting) or in equipment operating in explosion hazardous areas (flange mounting). The sockets and plugs are fitted with 3, 4, or 5-pin connectors appropriately selected for the application.

Selection and operation of Ex ATEX explosion-proof connectors

When selecting Ex explosion-proof connectors, first of all check that the manufacturer has the relevant certificates and declarations. Within the European Union, these will be the ATEX Certificate and the EU Declaration of Conformity. For applications outside the European Union, the global IECEx safety certificate will be relevant.

In addition to the ATEX / IECEx certification, familiarise yourself with the specifications of the explosion-proof connectors so that the material design is compatible with the industrial conditions that will exist in the spaces where the plugs and sockets will be installed.

Ex HARDO connectors

Thus, the explosion-proof HARDO connectors have a construction made of glass fibre reinforced resin BMC, which ensures durability and resistance to corrosion, temperature extremes, electrostatics and mechanical impact. All our connectors are made to a high IP66 rating. This means that the plug is sealed in the socket, and thus the entire connection is completely dustproof and resistant to high-pressure water. The above features allow HARDO explosion-proof connectors to be used in the vast majority of industrial spaces.

When selecting explosion-proof connectors, you can’t forget their most important purpose, which is to be able to connect electrical appliances. An incorrectly selected socket with a plug in terms of electrical parameters may increase the risk of the appliance overheating, or it may simply not allow the appliance to function properly. In this respect, the HARDO range is very flexible. By choosing the right plugs and sockets, you have a choice of many configurations within the range:

• The number of 3P / 4P / 5P poles.
• Rated current 16A / 32A / 63A / 125A (others on request)
• Rated voltages for 16A / 32A / 63A / 125A: 200~250V AC; 380~415V AC; 480~500V AC; 600~690V AC. For 16A additionally possible 110~130V AC.

See more about HARDO Ex plugs and sockets

Ex connectors – operating principles

Among the important considerations for the safe operation of explosion-proof connectors, it is worth noting whether the plugs and sockets selected have:

• possibility to lock the socket with a padlock: this is an additional protection against unauthorised or accidental use
• protection against accidental disconnection, which guarantees the continuity of the power supply and eliminates the risk of sparking due to a loose connection,
• integrated internal earthing: this ensures continuity of electric shock protection throughout the plug-socket system,
• visual colour differentiation, which ensures quick and safe identification of the plugs and their connection to the correct sockets, especially in situations where several sockets are installed next to each other,

Principles of proper maintenance of Ex connectors

Finally, it is worth mentioning the principles of safe and proper maintenance of connectors intended for use in hazardous areas. Of course, the basis for maintenance in the case of connectors, as with other electrotechnical equipment, is regular technical inspections. You must always carry out regular inspections according to the service schedule to catch any loosening, signs of corrosion, or wear on individual components at a safe moment.

Remember that the use of defective equipment, regardless of the fact that the equipment in question is ATEX certified. Therefore, if you notice any cracks, burns, or signs of wear, remember that these are a signal for immediate replacement.