Categories of equipment

The categories of equipment destined to work in these types of atmospheres are grouped according to:

1. Apparatus Group I: For work in mines or in external installations where explosive atmospheres can be produced.

  1. Category M1: Very high protection level.
  2. Category M2: High protection level

2. Group II devices: For use in other places where there may be a danger of explosive atmospheres.

  1. Category 1: Very high protection level. Even if one means of protection fails, there is another that continues to maintain the level of protection.
  2. Category 2: High level of protection.
  3. Category 3: Normal level of protection.

Electrical equipment suitable for explosive zones

Electrical equipment shall only be suitable for explosive areas if it is constructed in accordance with one of the following protection modes:

  • D = explosion-proof enclosure. Electrical equipment is enclosed within a housing capable of resisting the explosion and not transmitting the ignition to the surrounding environment, either by its joints or by other communications.
  • E = increased security. It is based on ensuring no arcing, sparking or overheating in equipment, taking: a high safety coefficient, special unlocked terminals, high quality insulation and a minimum IP54.
  • I = intrinsic safety. An apparatus or circuit is intrinsically safe when it is not capable of producing sparks or thermal effects sufficient to cause the ignition of a given gas atmosphere. It is indicated for instrumentation, since it consists in designing circuits in low tension and reducing the intensity taking also in consideration the possible defects that can occur and the storage of energy in capacitors, cables and inductances.
  • P = internal overpressure. Electric machines or materials are provided with an enclosure or installed in a room in which flammable gases or vapors are prevented from entering, keeping air or non-flammable gas inside them, at a pressure higher than the outside atmospheric pressure.
  • = Immersion in oil. It is made in such a way that flammable gases or vapors above the oil level and on the outside of the enclosure can not ignite.
  • Q = powdery insulation. The live parts of the electrical material are completely immersed in a mass of pulverulent insulation.
  • M = encapsulated. The elements to be protected are enclosed in a resin, in such a way that an explosive atmosphere can not be ignited by sparks, nor by contact hot parts internal to the encapsulation.