AS 2380.7-1987

1 - AS 2380.7-1987 ELECTRICAL EQUIPMENT FOR EXPLOSIVE ATMOSPHERES - EXPLOSION-PROTECTION TECHNIQUES - INTRINSIC SAFETY i
4 - PREFACE
5 - CONTENTS
7 - SECTION 1. SCOPE AND GENERAL
7 - 1.1 SCOPE.
7 - 1.2 REFERENCED DOCUMENTS.
7 - 1.3 DEFINITIONS.
7 - 1.3.1 Associated electrical equipment
8 - 1.3.2 Electrical equipment
8 - 1.3.3 Fault
8 - 1.3.4 Infallible component or infallible assembly of components
8 - 1.3.5 Intrinsically safe circuit
8 - 1.3.6 Intrinsically safe electrical equipment
8 - 1.3.7 Intrinsically safe electrical system
8 - 1.3.8 Normal operation
8 - 1.3.9 Self-revealing fault
8 - 1.4 GROUPING AND CLASSIFICATION.
8 - 1.5 TEMPERATURES.
8 - 1.6 CATEGORIES.
8 - 1.6.1 General requirements.
8 - 1.6.2 Category ‘ia’.
8 - 1.6.3 Category ‘ib’.
8 - 1.7 SAFETY FACTORS.
8 - 1.8 CERTIFICATION.
10 - SECTION 2. CONSTRUCTIONAL REQUIREMENTS
10 - 2.1 GENERAL REQUIREMENTS.
10 - 2.2 WIRING.
10 - 2.3 MOUNTING OF COMPONENTS.
10 - 2.4 OUTER ENCLOSURES.
10 - 2.5 FACILITIES FOR CONNECTION OF EXTERNAL CIRCUITS.
10 - 2.5.1 Terminals.
10 - 2.5.2 Plugs and sockets.
12 - 2.6 CLEARANCES, CREEPAGE DISTANCES, AND DISTANCES THROUGH CASTING COMPOUND AND INSULATIONS.
12 - 2.6.1 General.
12 - 2.6.2 Assessment.
12 - 2.6.3 Printed circuits.
12 - 2.6.4 Relays.
12 - 2.6.5 Encapsulation.
12 - 2.7 EARTHING.
13 - 2.8 INSULATION.
13 - 2.8.1 Segregated circuits.
13 - 2.8.2 Non-segregated circuits.
13 - 2.8.3 Inductive or capacitive interference.
13 - 2.8.4 Separation.
13 - 2.9 INTRINSICALLY SAFE ELECTRICAL SYSTEMS.
13 - 2.9.1 General.
13 - 2.9.2 External parameters.
13 - 2.9.3 Multicore cables in Zone 1.*
13 - 2.9.4. Multicore cables in Zone 0.*
15 - 2.9.5 Fibre optic cable.
15 - 2.10 PIEZO-ELECTRIC DEVICES.
16 - SECTION 3. REQUIREMENTS FOR COMPONENTS
16 - 3.1 COMPONENTS ON WHICH INTRINSIC SAFETY DEPENDS.
16 - 3.1.1 Rating of components.
16 - 3.1.2 Connectors for internal connections, plug-in cards and components
16 - 3.1.3 Cells and batteries.
16 - 3.1.4 Semiconductors.
16 - 3.2 INFALLIBLE COMPONENTS AND INFALLIBLE ASSEMBLIES OF COMPONENTS.
16 - 3.2.1 General.
16 - 3.2.2 Mains transformers.
18 - 3.2.3 Transformers other than mains transformers
18 - 3.2.4 Damping windings.
18 - 3.2.5 Current-limiting resistors.
18 - 3.2.6 Fuse-protected resistors.
18 - 3.2.7 Capacitors.
18 - 3.2.8 Safety shunts.
18 - 3.2.9 Optical coupling devices.
19 - SECTION 4. REQUIREMENTS FOR SAFETY BARRIERS
19 - 4.1 GENERAL.
19 - 4.2 PROVISION OF DIODES.
19 - 4.3 EARTHING.
19 - 4.4 PROTECTIVE MEASURES.
19 - 4.5 RATING OF BARRIER COMPONENTS.
19 - 4.5.1 General.
19 - 4.5.2 Barriers protected by resistors.
19 - 4.5.3 Barriers protected by fuses.
19 - 4.6 CONSTRUCTION.
19 - 4.6.1 Provision for mounting.
19 - 4.6.2 Facilities for connection to earth.
19 - 4.6.3 Separation of connection facilities.
19 - 4.6.4 Protection of components.
19 - 4.7 ROUTINE TESTS.
19 - 4.7.1 Completed barriers.
19 - 4.7.2 Diodes for 2-diode ‘ia’ barriers.
20 - SECTION 5. TYPE TESTS FOR ELECTRICAL EQUIPMENT
20 - 5.1 GENERAL.
20 - 5.2 SPARK TEST APPARATUS.
20 - 5.3 TEST MIXTURES.
20 - 5.4 CALIBRATION OF THE SPARK TEST APPARATUS
20 - 5.5 TESTS WITH THE SPARK TEST APPARATUS.
20 - 5.5.1 Procedure.
20 - 5.5.2 Safety factors.
21 - 5.5.3 Result of spark tests.
21 - 5.6 VOLTAGE TEST.
21 - 5.7 IMPACT TEST.
22 - SECTION 6. MARKING
22 - 6.1 MARKING OF ELECTRICAL EQUIPMENT.
22 - 6.2 MARKING OF DIODE SAFETY BARRIERS.
22 - 6.3 MARKING OF CONNECTION FACILITIES.
22 - 6.4 MARKING OF INTEGRATED INTRINSICALLY SAFE SYSTEMS
22 - 6.5 EXAMPLES OF MARKING.
22 - 6.5.1 Self-contained equipment.
22 - 6.5.2 Entity concept equipment.
22 - 6.5.3 Integrated systems.
22 - 6.5.4 Diode safety barriers.
22 - 6.5.5 Associated electrical equipment protected by an Ex d enclosure.
23 - APPENDIX A - GUIDANCE ON DESIGN AND ASSESSMENT OF INTRINSICALLY SAFE CIRCUITS
23 - A1 INTRODUCTION.
23 - A2 REFERENCE CURVES.
23 - A3 PROCEDURE.
23 - A4 LIMITATIONS IN APPLICATION.
24 - A5 EFFECT OF EXTERNAL INTERCONNECTING CABLES.
24 - A6 EXAMPLES.
24 - A6.1 Simple inductive circuit.
25 - A6.2 Simple capacitive circuit.
37 - APPENDIX B - GUIDANCE ON DESIGN AND ASSESSMENT OF SHUNT DIODE SAFETY BARRIERS
37 - B1 INTRODUCTION.
37 - B2 TYPICAL DESIGNS.
37 - B3 FUSE DATA.
40 - B4 EXTERNAL PARAMETERS.
44 - APPENDIX C - DETERMINATION OF EXTERNAL PARAMETERS
44 - C1 CERTIFICATION METHODS.
44 - C2 PARAMETERS TO BE DEFINED.
44 - C2.1 Entity concept intrinsically safe equipment.
44 - C2.2 Certified intrinsically safe systems.
44 - C3 CALCULATION OF PARAMETERS.
44 - C3.1 General.
44 - C3.2 Output parameters.
46 - C3.3 Input parameters.
46 - C3.4 Cable parameters.

Specifies design, construction and testing requirements for intrinsically safe electrical equipment for use in explosive atmospheres. Includes requirements for self-contained equipment, equipment forming a part of a system (entity concept equipment) and integrated systems. Also covers shunt diode safety barriers and other associated equipment intended for installation in a safe area. An appendix provides guidelines on the design and assessment of intrinsically safe circuits. Technically similar to IEC 79-11.

This standard specifies requirements for intrinsically safe electrical equipment and systems, type of protection i, intended for use in explosive atmospheres.This standard supplements AS 2380, Part 1, except for the following requirements which do not apply:(a) For intrinsically safe equipment and associated equipment:Clause 2.1.4(b) Access to uninsulated live partsClause 2.4.2 Special fastenersClause 2.5 Interlocking devicesClause 2.6 Bushings and terminal studsClause 2.7 Materials used for cementing and sealingClause 2.8 ConnectionsClause 2.12 Cable and conduit entriesSection 3 Supplementary requirements for certain electrical equipmentClause 5.2.1 Impact testClause 5.2.3 Rubbing of moving partsClause 5.4 Torque test for bushings(b) For associated electrical equipment:Clause 2.2 Plastics enclosuresClause 2.3 Light alloy enclosuresClause 5.5 Temperature rise testClause 5.6 Thermal shock testClause 5.7 Insulation resistance test of parts of enclosures of plastics materialsWhere associated electrical equipment is protected by a type of explosion-protection other than intrinsic safety, the requirements of the applicable standard for that type of protection shall apply.This standard applies also to electrical equipment or parts of electrical equipment located outside the explosive atmosphere or protected by another type of explosion-protection, where the intrinsic safety of the electrical circuits in the explosive atmosphere may depend upon the design and construction of such electrical equipment or parts of such electrical equipment.NOTE: The permitted methods of interconnection of intrinsically safe electrical equipment and associated electrical equipment are specified in AS 1076, Part 4.

Superseded on 28 February 2005