Question: E-Motor Ex Proof Selection

**kurt.rock** · 05-20-2013, 04:40 AM

Salam to all,

Is there anybody who could explain how selection of ex proof for motor is done?

There are Ex 'e, Ex 'n, Ex 'p, etc...

But how exactly we choose any of those to fit the area (Zone 1, Zone 2, etc.)

General explanation on this matter shall be appreciated.

Thank you in advance.

**Sajid Ali Khan** · 06-02-2013, 06:45 AM

Dear Kurt.rock,
In Industry a large range of liquids, vapours and gases that form explosive mixtures when combined with air, pose a great explosion hazard if a source of ignition through spark, heat or similar energy is present.
Wherever such gases are processed, stored, transported, dispensed or vented such explosion hazard is present. In case the mixture of explosive gas to air is within the range of explosion, that atmosphere is called "Classified Area," and is a 3D envelope surrounding the source of explosive gas. Explosion Protection is the science and engineering of preventing such explosions. Ex 'e", Ex 'd' etc are all mitigation measures for avoiding these explosion risks.

Your question is not just limited to electric motors but all electrical and instrumentation equipment (E&I or I&E) installed in explosion classified areas.
Selection of I&E equipment in classified environment is really not that difficult, if the installation is properly classified. However, the Design/Maintenance Engineer must have sufficient knowledge about the risks, safety measures, which engineering standards are applicable, what is area classification, which mitigation measures are permitted, what maintenance must be done to ensure integrity of the mitigation measures, etc

International Electrotechnical Commission's (IEC) 60079 series of Standards are one of the most widely applied for all aspects of risks due to explosive gases. The most important being:
IEC 60079- Electrical Apparatus for Explosive Gas Atmospheres
• Part 0 General requirements
• Part 1 Construction and test of flameproof enclosures of electrical apparatus
• Part 2 Electrical apparatus - type of protection ‘p’
• Part 3 Spark test apparatus for intrinsically safe circuits
• Part 7 Increased safety ‘e'
• Part 10 Classification of hazardous areas
• Part 11 Construction and test of intrinsically safe and associated apparatus
• Part 14 Installation (and selection) of equipment in hazardous areas
• Part 17 Inspection and maintenance of equipment

You will be able to find these Standards, books etc on this very forum, if you use the key words used in my reply.

Sajid Ali Khan