1 Scope
1.1 This part of GB 3836 contains the specific requirements for construction and assessment of intrinsically safe electrical systems, type of protection “i”, intended for use, as a whole or in part, in explosive atmospheres in Group II locations. This standard is intended for use by the designer of the system who may be a manufacturer, a specialist consultant or a member of the end-user’s staff.
NOTE 1 The detailed requirements for construction and assessment of intrinsically safe electrical systems in Group I and Group III locations are intended to be given out in the next revision of this part.
1.2 This part supplements GB 3836.4-2010, the requirements of which apply to electrical apparatus used in intrinsically safe electrical systems.
As for the apparatus in Group II system intended for used in the explosive atmospheres, the groups of whose surface temperature shall be given out in accordance with GB 3836.1 and GB 3836.4.
NOTE 2 The detailed requirements for “ic” intrinsically safe systems are intended to be given out in the next revision of this part.
1.3 The installation requirements of a Group II system designed in accordance with this part are specified in GB 3836.15-2000.
2 Normative References
The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.
GB 3836.1 Explosive atmospheres—Part 1: Equipment—General requirements (GB 3836.1-2010, IEC 60079-0:2007, MOD)
GB 3836.4-2010 Explosive atmospheres—Part 4: Equipment protection by intrinsic safety i (IEC 60079-11:2006, MOD)
GB 3836.15-2010 Electrical apparatus for explosive gas atmospheres-Part 15: Electrical installations in hazardous areas (other than mines) (eqv IEC 60079-14:1998)
GB/T 16927.1 High voltage test techniques--Part 1: General test requirements (GB/T 16927.1-1997, eqv IEC 60060-1:1989)
3 Definitions
For the purposes of this document, the following definitions, specific to intrinsically safe electrical systems, apply. They supplement the definitions which are given in GB 3836.1-2010 and GB 3836.4-2010.
3.1 Intrinsically safe electrical system
Assembly of interconnected items of electrical apparatus, described in a descriptive system document, in which the circuits or parts of circuits, intended to be used in an explosive atmosphere, are intrinsically safe circuits
3.1.1 Certified intrinsically safe electrical system
Electrical system conforming to 3.1 for which a certificate has been issued confirming that the electrical system complies with this standard
3.1.2 Uncertified intrinsically safe electrical system
Electrical system conforming to 3.1 for which the knowledge of the electrical parameters of the items of certified intrinsically safe electrical apparatus, certified associated apparatus, simple apparatus and the knowledge of the electrical and physical parameters of the interconnecting wiring permit the unambiguous deduction that intrinsic safety is preserved
3.2 Descriptive system document
Document in which the items of electrical apparatus, their electrical parameters and those of the interconnecting wiring are specified
3.3 System designer
Person who is responsible for the descriptive system document, has the necessary competence to fulfill the task and who is empowered to enter into the commitments on behalf of his employer
3.4 Maximum cable capacitance (Cc)
Maximum capacitance of the interconnecting cable that can be connected into an intrinsically safe circuit without invalidating intrinsic safety
3.5 Maximum cable inductance (Lc)
Maximum inductance of the interconnecting cable that can be connected into an intrinsically safe circuit without invalidating intrinsic safety
3.6 Maximum cable inductance to resistance ratio (Lc/Rc)
Maximum value of the ratio inductance (Lc) to resistance (Rc) of the interconnecting cable that can be connected into an intrinsically safe circuit without invalidating intrinsic safety
3.7 Linear power supply
Power source from which the available output current is determined by a resistor. The output voltage decreases linearly as the output current increases
3.8 Non-linear power supply
Power supply where the output voltage and output current have a non-linear relationship
EXAMPLE A supply with a constant voltage output up to a constant current limit controlled by semiconductors.
