Flameproof Enclosure 'd'

Background:

This protection prevents any explosion transmission from inside of enclosure to outside because:

• The motor itself is 'explosion proof' which means that in case of any explosion inside the motor the explosion is not transmitted to the explosive atmosphere outside the enclosure.
• The maximum surface temperature outside the motor does not exceed the temperature class for which the motor is certified
• No sparks occur outside the motor enclosure.

The EHSRs of ATEX Directive corresponding to category 2 must be followed.

• Any parts which can ignite an explosive atmosphere are placed in enclosure, measures are taken to ensure that the enclosure withstands the pressure developing during an internal explosion and prevents the transmission to the explosive atmosphere surrounding the enclosure.
• Equipment must be fitted with suitable cable and conduit entries

To be installed in Zone 1, the motor must comply with Category 2 requirements, even though it is used in Zone 2.

This type of protection can be used for electrical and non-electrical equipment.

Motors can be designed:

• with stator enclosure and terminal box 'd' protected
• or with stator enclosure 'd' protected and terminal box 'increased safety e' protected

Standards concerned with protection type 'd':
EN 60079-0: 2004-03	Electrical apparatus for explosive gas atmospheres. Part 0: General requirements.
EN 60079-1: 2004-03	Electrical apparatus for explosive gas atmospheres. Part 1: Flameproof enclosure 'd'.
EN 50014: June 1997	Electrical apparatus for potentially explosive atmospheres. General requirements.
EN 50018: November 2000	Electrical apparatus for potentially explosive atmospheres. Flameproof enclosure 'd'.
IEC 60079-0: 2004-01	Electrical apparatus for explosive gas atmospheres. Part 0: General requirements.
IEC 60079-1: 2003-11	Electrical apparatus for explosive gas atmospheres. Part 1: Flameproof enclosure 'd'.
dg

Standards concerned with the terminal box 'e' protected:
EN 60079-0: 2004-03	Electrical apparatus for explosive gas atmospheres. Part 0: General requirements.
EN 60079-7: 2003-08	Electrical apparatus for explosive gas atmospheres. Part 7: Increased safety 'e'.
EN 50014: June 1997	Electrical apparatus for potentially explosive atmospheres. General requirements.
EN 50019: July 2000	Electrical apparatus for potentially explosive atmospheres. Increased safety 'e'.
IEC 60079-0: 2004-01	Electrical apparatus for explosive gas atmospheres. Part 0: General requirements.
IEC 60079-7: 2001-11	Electrical apparatus for explosive gas atmospheres. Part 7: Increased safety 'e'.

Marking:	Old EN	IEC / New EN
Stator and terminal box 'd'	EEx d	Ex d
Stator 'd' and terminal box 'e'	EEx de	Ex de
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Design:
The motor enclosure is designed in such a way that it withstands without damage any pressure levels caused by an internal explosion with a minimum safety factor = 1.5.

It is checked with safety factors required by the standards that the enclosure resists explosure pressure without any effect on the outside environment. Surface temperature is not exceeding the temperature class according to which the motor is certified.

Maximum surface temperature is checked at the rated power of motor in case of voltage supply in the worst conditions for not exceeding the temperature class certified.