Requirements for IP protection level of explosion-proof equipment used in places with combustible dust
1、 What is the IP protection level?
IP level, also known as enclosure protection level, is an abbreviation for Ingress Protection. IP level is the protection level for electrical equipment enclosures against foreign object intrusion, derived from the International Electrotechnical Commission's standard IEC 60529, which was also adopted as a national standard in the United States in 2004.
For the protection of foreign objects by electrical equipment enclosures, the format of IP rating is IPXX, where XX is two Arabic numerals, the first X represents the dust protection level of the equipment, and the highest is basically 6; The second X represents the waterproof level of the device, with a maximum of 8. The specific protection level can refer to the table below (the higher the number, the higher the protection level).
2、 Requirements for IP protection level of explosion-proof equipment used in places with combustible dust
(1) Generally speaking, intrinsic safety devices do not require enclosures as protective measures as they have already taken measures for the circuit itself. However, due to the potential weakening of intrinsic safety performance by conductive components, such as any type of dust that may reduce reliable creepage distance, according to the requirements of IEC61241-0:2004, equipment enclosures should meet at least the IP6X protection level requirements specified in GB4208-2008.
(2) Equipment components without IP6X external protection level, if effectively sealed with a thickness of not less than 1mm, should be considered to effectively prevent dust from entering.
(3) In other cases, the level of enclosure protection that the equipment needs to achieve is determined by the specific usage conditions of the equipment.
2. Shell protection type tD
(1) For A-type dust tight equipment, various enclosures including rotating motors should comply with the IP6X requirements specified in GB4208.
(2) For A-type dust-proof equipment, including rotating motors, various enclosures should comply with the IP5X testing and qualification requirements specified in GB4208.
(3) For A-type dust tight enclosures, the protection level should not be lower than IP6X in Zone 20, Zone 21, and Zone 22 with conductive dust, and not lower than IP5X in Zone 22.
3. Sealing protection type mD and positive pressure protection type pD
There is no clear requirement for the protection level of equipment in the standard GB 12476 for the sealing protection type mD and positive pressure protection type pD. However, in the actual certification and testing process, it is still necessary to make requirements and measurements for the protection level based on the actual use and scenario of the product.
3、 Supplementary regulations
According to the provisions of GB/T4942.1-2005, the protection level of the ventilation holes for the external fans of rotating motors should be at least IP20 for the inlet end and IP10 for the outlet end.
For zones 21 and 22, when the rated current does not exceed 10A and the rated voltage does not exceed 250VAC or 69VDC, plugs and sockets do not need to meet the requirements of 12476.1.19.1 if they simultaneously meet the following requirements:
1) The socket is connected to the power side.
2) There is an arc extinguishing delay time before the plug and socket are disconnected.
3) During the arc extinguishing period, the plug and socket comply with IP6X dust tight enclosure.
Luminaires equipped with interlocking devices for opening and disconnecting power should be protected by an internal shell with an additional protection level of not less than IP30 for live components in order to minimize the risk of explosion, and should be accompanied by a warning sign that reads' Do not open with live power '.
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