Explosive atmospheres—
Part 3: Equipment protection by increased safety "e"
1 Scope
This standard specifies the requirements for the design, construction, testing and marking of electrical equipment and Ex Components with type of protection increased safety “e” intended for use in explosive gas atmospheres.
Levels of protection of increased safety “e” electrical equipment and Ex Components are either:
a) Level of Protection “eb” (EPL “Mb” or “Gb”); or
b) Level of Protection “ec” (EPL “Gc”).
Level of Protection “eb” applies to equipment or Ex Components, including their connections, conductors, windings, lamps, and batteries; but not including semiconductors or electrolytic capacitors.
Note 1: The use of electronic components, such as semiconductors or electrolytic capacitors, is excluded from Level of Protection “eb” as expected malfunctions could result in excessive temperatures or arcs and sparks if the internal separation distances were not applied. It is not generally practical to maintain those separation distances and maintain the function of the electronic component.
Level of Protection “ec” applies to equipment or Ex Components, including their connections, conductors, windings, lamps, and batteries; and also including semiconductors and electrolytic capacitors.
Note 2: The use of electronic components, such as semiconductors or electrolytic capacitors, is permitted in Level of Protection “ec” as these are evaluated under both normal conditions and regular expected occurrences, and are not likely to result in excessive temperatures or arcs and sparks. As the requirements for separation distances are not applied to the internal construction, commercially available electronic components are generally suitable if the external separation distances comply.
The requirements of this standard apply to both Levels of Protection unless otherwise stated.
For Level of Protection “eb”, this standard applies to electrical equipment where the rated voltage does not exceed 11 kV r.m.s., a.c. or d.c.
For Level of Protection “ec”, this standard applies to electrical equipment where the rated voltage does not exceed 15 kV r.m.s., a.c. or d.c.
Note 3: Short circuit currents flowing through increased safety connections of mains circuits are not considered to create a significant risk of ignition of an explosive gas atmosphere due to movement of connections as a result of mechanical stresses created by the short circuit current. Normal industrial standards require that the effects of short time high currents on the security of connections be considered. The presence of the explosive gas atmosphere does not adversely affect the security of the connection.
Note 4: Any short term thermal excursions that occur as a result of electrical current excursions above normal rated currents, such as those that occur during the starting of motors, are not considered to create a significant risk of ignition of an explosive gas atmosphere due to the relatively short duration of the event and the convection that occurs during the event.
Note 5: High-voltage connections and associated wiring (above 1 kV) can be susceptible to increased partial discharge activity that could be a source of ignition. Increased spacings to earthed surfaces or other connections and provision of suitable high-voltage stress relief for the terminations are typically provided.
This standard supplements and modifies the general requirements of GB/T 3836.1. Where a requirement of this standard conflicts with a requirement of GB/T 3836.1, the requirement of this standard will take precedence.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
GB/T 755 Rotating electrical machines—Rating and performance (GB/T 755-2019, IEC 60034-1: 2017, IDT)
GB/T 1040.2 Plastics—Determination of tensile properties—Part 2: Test conditions for moulding and extrusion plastics (GB/T 1040.2-2006, ISO 527-2: 1993, IDT)
GB/T 1312 Lampholders for tubular fluorescent lamps and starter holders (GB/T 1312-2007, IEC 60400: 2004, IDT)
GB/T 1406.1 Types and dimensions of lamp caps—Part 1: Screw caps (GB/T 1406.1-2008, IEC 60061-1: 2005, MOD)
GB/T 1406.2 Types and dimensions of lamp caps—Part 2: Pin lamp caps (GB/T 1406.2-2008, IEC 60061-1: 2005, MOD)
GB/T 1406.5 Types and dimensions of lamp caps—Part 5: Bayonet caps (GB/T 1406.5-2008, IEC 60061-1: 2005, MOD)
GB/T 2423.5-2019 Environmental testing—Part 2: Test methods—Test Ea and guidance: Shock (IEC 60068-2-27: 2008, IDT)
GB/T 2423.10 Environmental testing—Part 2: Tests methods—Test Fc: Vibration (sinusoidal) (GB/T 2423.10-2019, IEC 60068-2-6: 2007, IDT)
GB/T 2423.19 Environmental testing—Part 2: Test methods—Test Kc: Sulphur dioxide test for contacts and connections (GB/T 2423.19-2013, IEC 60068-2-42: 2003, IDT)
GB/T 2828.1 Sampling procedures for inspection by attributes—Part 1: Sampling schemes indexed by acceptance quality limit (AQL) for lot-by-lot inspection (GB/T 2828.1-2012, ISO 2859-1: 1999, IDT)
GB/T 3836.1 Explosive atmospheres—Part 1: Equipment—General requirements (GB/T 3836.1-2021, IEC 60079-0: 2017, MOD)
GB/T 3836.2 Explosive atmospheres—Part 2: Equipment protection by flameproof enclosures “d” (GB/T 3836.2-2021, IEC 60079-1: 2014, MOD)
GB/T 3836.4 Explosive atmospheres—Part 4: Equipment protection by intrinsic safety "i” (GB/T 3836.4-2021, IEC 60079-11: 2011, MOD)
GB/T 3956 Conductors of insulated cables (GB/T 3956-2008, IEC 60228: 2004, IDT)
GB/T 4207 Method for the determination of the proof and the comparative tracking indices of solid insulating materials (GB/T 4207-2012, IEC 60112: 2009, IDT)
GB/T 4208 Degrees of protection provided by enclosure (IP code) (GB/T 4208-2017, IEC 60529: 2013, IDT)
GB/T 6109.2 Enamelled round winding wire—Part 2: Polyesterimide enamelled round copper wire, class 155 (GB/T 6109.2-2008, IEC 60317-3: 2004, IDT)
GB/T 6109.5 Enamelled round winding wire—Part 5: Polyesterimide enamelled round copper wire, class 180 (GB/T 6109.5-2008, IEC 60317-8: 1997, IDT)
GB/T 6109.20 Enamelled round winding wire—Part 20: Polyester or polyesterimide overcoated with polyamide-imide enamelled round copper wire, class 200 (GB/T 6109.20-2008, IEC 60317-13: 1997, IDT)
GB/T 6109.22 Enamelled round winding wire—Part 22: Aromatic polyimide enamelled round copper wire, class 240 (GB/T 6109.22-2008, IEC 60317-46: 1997, IDT)
GB 7000.1 Luminaires—Part1: General requirements and tests (GB 7000.1-2015, IEC 60598-1: 2014, IDT)
GB/T 9341 Plastics—Determination of flexural properties (GB/T 9341-2008, ISO 178: 2001, IDT)
GB/T 10681 Tungsten filament lamps for domestic and similar general lighting purposes—Performance requirements (GB/T 10681-2009, IEC 60064: 2005 A4: 2007, NEQ)
GB/T 10682 Double-capped fluorescent lamps—Performance specification (GB/T 10682-2010, IEC 60081: 2005, NEQ)
GB/T 11021 Electrical insulation—Thermal evaluation and designation (GB/T 11021-2014, IEC 60085: 2007, IDT)
GB/T 11026.1 Electrical insulating materials—Thermal endurance properties—Part 1: Ageing procedures and evaluation of test results (GB/T 11026.1-2016, IEC 60216-1: 2013, IDT)
GB/T 11026.2 Electrical insulating materials—Thermal endurance properties—Part 2: Choice of test criteria (GB/T 11026.2-2012, IEC 60216-2: 2005, IDT)
GB/T 13140.5 Connecting devices for low-voltage circuits for household and similar purposes—Part 2: Particular requirements for twist-on connecting devices (GB/T 13140.5-2008, IEC 60998-2-4: 2004, IDT)
GB/T 14048.1 Low-voltage switchgear and controlgear—Part 1: General rules (GB/T 14048.1-2012, IEC 60947-1: 2011, MOD)
GB/T 14048.7 Low-voltage switchgear and controlgear—Part 7-1: Ancillary equipment—Terminal blocks for copper conductors (GB/T 14048.7-2016, IEC 60947-7-1: 2009, MOD)
GB/T 14048.8 Low-voltage switchgear and controlgear—Part 7-2: Ancillary equipment—Protective conductor terminal blocks for copper conductors (GB/T 14048.8-2016, IEC 60947-7-2: 2009, MOD)
GBT 14048.22 Low-voltage switchgear and controlgear—Part 7-4: Ancillary equipment—PCB terminal blocks for copper conductors (GB/T 14048.22-2017, IEC 60947-7-4: 2013, IDT)
GB 14196.1 Incandescent lamps—Safety specifications—Part 1: Tungsten filament lamps for domestic and similar general lighting purposes (GB 14196.1-2008, IEC 60432-1: 2005, IDT)
GB 14196.2 Incandescent lamps—Safety specifications—Part 2: Tungsten halogen lamps for domestic and similar general lighting purposes (GB 14196.2-2008, IEC 60432-2: 2005, IDT)
GB 14196.3 Incandescent lamps—Safety specifications—Part 3: Tungsten-halogen lamps (non-vehicle) (GB 14196.3-2008, IEC 60432-3: 2005, IDT)
GB/T 16935.1 Insulation coordination for equipment within low-voltage systems—Part 1: Principles requirements and tests (GB/T 16935.1-2008, IEC 60664-1: 2007, IDT)
GB/T 17464 Connecting devices—Electrical copper conductors—Safety requirements for screw-type and screwless-type clamping units—General requirements and particular requirements for clamping units for conductors from 0.2 mm2 up to 35 mm2 (included) (GB/T 17464-2012, IEC 60999-1: 1999, IDT)
GB/T 17935 Edison screw lampholders (GB/T 17935-2007, IEC 60238: 2004, IDT)
GB/T 17936 Bayonet lampholders (GB/T 17936-2007, IEC 61184: 2004, IDT)
GB 18774 Double-capped fluorescent lamps—Safety specifications (GB 18774-2002, IEC 61195: 1999, IDT)
GB/T 19148.1 Types and dimensions of lampholder—Part 1: Screw lampholder (GB/T 19148.1-2008, IEC 60061-2: 2004, MOD)
GB/T 19148.2 Types and dimensions of lampholders—Part 2: Pin lampholders (GB/T 19148.2-2008, IEC 60061-2: 2004, MOD)
GB 19510.1 Lamp controlgear—Part 1: General and safety requirements (GB 19510.1-2009, IEC 61347-1: 2007, IDT)
GB 19510.4 Lamp controlgear—Part 4: Particular requirements for a. c. supplied electronic ballasts for fluorescent lamps (GB 19510.4-2009, IEC 61347-2-3: 2000, IDT)
GB/T 19518.1 Explosive atmospheres—Electrical resistance traces heating—Part 1: General and testing requirements (GB/T 19518.1-2017, IEC 60079-30-1: 2007, MOD)
GB 19652 Discharge lamps (excluding fluorescent lamps)—Safety specification (GB 19652-2005, IEC 62035: 1999, IDT)
GB/T 20636 Connecting device—Electrical copper conductors—Safety requirements for screw-type and screwless-type clamping units—Particular requirements for conductors above 35 mm2 up to 300 mm2 (GB/T 20636-2006, IEC 60999-2: 2003, IDT)
GB/T 20840.2 Instrument transformers—Part 2: Additional requirements for current transformers (GB/T 20840.2-2014, IEC 61869-2: 2012, MOD)
GB/T 21211 Equivalent loading and superposition techniques—Indirect testing to determine temperature rise of rotating electrical machines (GB/T 21211-2017, IEC 60034-29: 2008, IDT)
3 Terms and definitions
For the purposes of this document, the terms and definitions given in GB/T 3836.1 and the following apply.
Note: For the definitions of any other terms, particularly those of a more general nature, please refer to GB/T 2900.35 or other appropriate parts of International Electrotechnical Vocabulary.
3.1
cell and battery types
3.1.1
sealed cell
cell which remains closed and does not release either gas or liquid when operated within the limits specified by the manufacturer
Note: A sealed cell is often equipped with a safety device to protect against a dangerously high internal pressure and is designed to operate during its life in its original sealed state.
3.1.2
valve-regulated cell or battery
secondary cell or battery which is closed under normal conditions but which has an arrangement which allows the escape of gas if the internal pressure exceeds a pre-determined value
Note: The cell cannot normally receive an addition to the electrolyte.
3.1.3
vented cell or battery
secondary cell or battery having a cover provided with an opening through which products of electrolysis and evaporation are allowed to escape freely from the cell or battery to the atmosphere
3.2
duty type (motor)
continuous, short-time or periodic duty, comprising one or more loads remaining constant for the duration specified, or a non-periodic duty in which generally load and speed vary within the permissible operating range
Note: These include duty types S1 to S10, as defined in GB/T 755.
3.3
ferrule
metal tube crimped over stranded wire to secure it within a terminal usually with electrical insulation protecting any exposed portion of the wire not completely inside the terminal post
3.4
fuse
device that by the fusing of one or more of its specially designed and proportioned components intended to melt under the action of current exceeding some definite value for a definite period of time, opens the circuit in which it is inserted by breaking the current when this exceeds a given value for a sufficient time
3.5
increased safety “e”
type of protection applied to electrical equipment or Ex Components in which additional measures are applied so as to give increased security against the possibility of excessive temperatures and against the occurrence of arcs and sparks
3.6
initial starting current
IA
highest r.m.s. value of current drawn by an a.c. motor when at rest or by an a.c. magnet with its armature clamped in the position of maximum air gap when supplied at rated voltage and rated frequency
Note: Transient phenomena are ignored.
Foreword i
Introduction ix
1 Scope
2 Normative references
3 Terms and definitions
4 Constructional requirements
4.1 Level of Protection
4.2 Electrical connections
4.3 Clearances
4.4 Creepage
4.5 Printed wiring boards with conformal coating, Level of Protection “ec”
4.6 Solid electrical insulating materials
4.7 Windings
4.8 Limiting temperature
4.9 Wiring internal to equipment
4.10 Degrees of protection provided by enclosures
4.11 Fasteners
5 Supplementary requirements for specific electrical equipment
5.1 General
5.2 Electrical machines
5.3 Luminaires, hand lights, or caplights
5.4 Measuring instruments and instrument transformers
5.5 Transformers other than instrument transformers
5.6 Supplementary requirements for equipment incorporating cells and batteries
5.7 General purpose connection and junction boxes
5.8 Resistance heating unit (other than trace heating systems)
5.9 Supplementary requirements for fuses
5.10 Other electrical equipment
6 Type verifications and type tests
6.1 Dielectric strength of insulation
6.2 Rotating electrical machines
6.3 Luminaires
6.4 Measuring instruments and instrument transformers
6.5 Transformers other than instrument transformers
6.6 Verification and tests of cells and batteries for Level of Protection “eb”
6.7 Verification and tests of cells and batteries for Level of Protection “ec”
6.8 General purpose connection and junction boxes
6.9 Resistance heating unit
6.10 Terminal insulating material tests
7 Routine verifications and routine tests
7.1 Dielectric tests
7.2 Dielectric tests for batteries
7.3 Inter-turn overvoltage tests
8 Ex Component certificates
8.1 General
8.2 Terminals
9 Marking and instructions
9.1 General marking
9.2 Ex Components enclosures
9.3 Instructions for use
9.4 Warning markings
10 Documentation
Annex A (Normative) Temperature determination of electrical machines—Methods of test and of calculation
Annex B (Normative) Type tests for specific forms of resistance heating devices or resistance heating units (other than trace heater)
Annex C (Informative) Cage motors—Thermal protection in service
Annex D (Informative) Resistance heating devices and units— Additional electrical protection
Annex E (Informative) Combinations of terminals and conductors for general purpose connection and junction boxes
Annex F (Normative) Dimensions of copper conductors
Annex G (Normative) Test procedure for T5 (only 8 W), T8, T10 and T12 lamp tubes
Annex H (Normative) Selection for separation distances of equipment for Level of Protection “ec” under controlled environments
Annex I (Informative) Application, installation, and testing considerations of asynchronous motors for Level of Protection “ec”
Annex J (Informative) Luminaires incorporating LEDs
Bibliography