AS/NZS 61241.4:2002

Electrical apparatus for use in the presence of combustible dust Type of protection 'pD'

Standards Australia

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1 - AS/NZS 61241.4:2002 ELECTRICAL APPARATUS FOR USE IN THE PRESENCE OF COMBUSTIBLE DUST - TYPE OF PROTECTION 'pD'
4 - PREFACE
5 - CONTENTS
7 - 1 Scope
7 - 2 Normative references
8 - 3 Definitions
8 - 3.1 type of protection ‘pD’
8 - 3.2 overpressure
9 - 3.3 pressurization
9 - 3.4 protective gas
9 - 3.5 enclosure
9 - 3.6 pressurized enclosure
9 - 3.7 static pressurization
9 - 3.8 pressurization with leakage compensation
9 - 3.9 pressurization with continuous flow of the protective gas
9 - 3.10 electrical apparatus
9 - 3.11 ignition-capable apparatus
10 - 3.12 self-revealing fault
10 - 3.13 opening
10 - 3.14 protective device
10 - 3.15 alarm
10 - 3.16 indicator
10 - 3.17 protected apparatus
10 - 3.18 pressurization system
10 - 3.19 alternate (or auxiliary) source of supply of protective gas
10 - 3.20 zones
10 - 3.21 zone 20
11 - 3.22 zone 21
11 - 3.23 zone 22
11 - 4 Pressurization principle
11 - 4.1 Protective gas
11 - 4.2 Automatic disconnection
11 - 4.3 Cleaning
11 - 4.4 Discharge of protective gas
12 - 5 General constructional requirements
12 - 5.1 Electrical performance of apparatus
12 - 5.2 Mechanical strength
12 - 5.3 Apertures
12 - 5.4 Electrical connections to enclosures
12 - 5.5 Doors and covers
13 - 6 Temperature limits
13 - 7 Safety provisions and safety devices (except for static pressurization)
13 - 7.1 General
14 - 7.2 Pressure- or flow-activated devices
14 - 7.3 Electrical supply
14 - 7.4 Switching off electrical supply
14 - 7.5 Failure of pressurization
14 - 7.5.1 Protection requirements
16 - 7.6 Level of overpressure
16 - 7.7 Possible sources of ignition
16 - 7.8 Enclosed components
16 - 7.9 Separate enclosures
16 - 8 Safety provisions and safety devices for static pressurization
17 - 9 Supply of protective gas
17 - 9.1 Type of gas
17 - 9.2 Second source of supply
17 - 9.3 Temperature
17 - 10 Verification and tests
17 - 10.1 General
18 - 10.2 Type verification and tests
18 - 10.3 Overpressure test
18 - 10.4 Minimum overpressure test
18 - 10.4.1 Test conditions
18 - 10.4.2 Number of tests
18 - 10.5 Leakage test
19 - 10.6 Impact test
19 - 10.7 Routine tests
19 - 10.7.1 Overpressure test
19 - 10.7.2 Leakage test
19 - 11 Marking
19 - 11.1 Pressurized enclosure
19 - 11.2 Additional marking
20 - 11.3 Pressurized enclosures protected by static pressurization
20 - 11.4 Any other marking required
21 - Annex A - Ducts for protective gas supply
24 - Annex B - Installation requirements for pressurization
24 - B.1 Source of protective gas
24 - B.2 Automatic switch-off
24 - B.3 Manual switch off
24 - B.4 Common supply of protective gas
25 - B.5 Switching off electrical supply

Abstract

Specifies the requirements for design, construction, testing and marking of electrical apparatus, with type of protection pressurization 'pD', intended for use in combustible dust atmospheres. This Standard is identical with and has been reproduced from IEC 61241-4:2001.

Scope

This part of IEC 61241, gives requirements on the design, construction, testing and marking of electrical apparatus for use in combustible dust atmospheres in which a protective gas (air or inert gas), maintained at a pressure above that of the external atmosphere, is used to prevent the entry of dust which might otherwise lead to the formation of a combustible mixture within enclosures which do not contain a source of combustible dust.
This standard contains the specific requirements for construction and testing, including protective requirements that apply to electrical apparatus with type of protection pressurization pD intended for use in potentially combustible dust atmospheres.
This standard includes the requirements for the construction of the enclosure and its associated components, including, if any, the inlet and outlet ducts for the protective gas, and for the safety provisions and devices necessary to ensure that pressurization is established and maintained for type of protection pressurization pD.
Requirements for pressurized enclosures with an internal source of dust release are not included in this standard.
This standard does not cover the requirements for pressurized rooms with or without internal sources of dust release.
This standard does not apply to dusts of explosives which do not require atmospheric oxygen for combustion or to pyrophoric substances.
This standard does not cover combined gas and dust hazard. Those requirements are under consideration.
The requirements contained in this standard are supplementary to those in IEC 61241.1.1.