1 Scope
This standard specifies the design requirements for isolation, shielding and grounding of instrumentation and control equipment in nuclear power plants and gives out the implementation methods for grounding and shielding.
This standard is applicable to the design, examination, maintenance and operation of grounding and shielding for instrumentation and control equipment in nuclear power plants.
2 Normative References
The following documents are indispensable for the application of this document. For dated references, only the dated editions apply. For undated references, the latest edition of the normative document (including any amendments) applies.
GB/T 13286-2008 Criteria for Independence of Class 1E Equipment and Circuits in Nuclear Power Plants
3 Terminologies and Definitions
For the purposes of this document, the following terminologies and definitions apply.
3.1
Electromagnetic noise
A kind of obvious time-varying electromagnetic phenomena without information transmission, which may be superposed or combined with useful signals.
3.2
Differential-mode (DM) noise
The noise voltage or current that appears in the same mode as the signal or power waveform on the disturbed circuit. DM noise is also referred to as transverse noise and normal mode noise.
Note: DM noise may be caused by one or more of the following:
a) Electrostatic fields linking unequally with the distributed capacitance of the distributed signal wires.
b) Magnetic induction linking magnetic fields unequally with the disturbed signal wires.
c) Electromagnetic wave coupling. Electric dipole (or monopole) antennas and/or magnetic loop antennas inadvertently formed in the signal wire or cable can detect electromagnetic wave radiation and cause it to appear as DM noise on the circuit conductors.
d) Junction or thermal potentials due to the use of dissimilar metals in the connection system.
e) CM to DM noise conversion in the disturbed path, particularly via transformer coupling actions.
3.3
Common-mode (CM) noise
The noise voltage and current that appear equally on each signal wire, power wire, control wire and between reference points and system grounding points. CM noise is also referred to as longitudinal-mode noise.
Foreword i
Introduction ii
1 Scope
2 Normative References
3 Terminologies and Definitions
4 Protective Design for Electromagnetic Interference
4.1 Safety Objective of Protective Design
4.2 Analysis for Interference Source and Mode
4.3 Criteria for arranging of Instrumentation and Control Equipment Cable
4.4 Criteria for Shielding and Grounding Design
5 Shielding Design
5.1 General Requirements for Shielding Design
5.2 Shielding of Signal Lines
5.3 Shielding of Electronic Equipment
6 Grounding of the Instrumentation and Control System
6.1 General Requirements
6.2 Equipment Safety Grounding
6.3 Signal Grounding
6.4 Signal Cable Shield Grounding
6.5 Grounding of Multiple-Channel Data Transmission System
6.6 Grounding of Computer System
6.7 Grounding of the Central Distribution Frame
6.8 Instrumentation Power Supply Grounding
7 Tests
7.1 Ground Loop Test
7.2 Insulation Resistance Test
Appendix A (Informative) Interference Source and Mode
Appendix B (Normative) Minimum Section Area of Grounding Conductor
Appendix C (Informative) Examples of Grounding Methods
Appendix D (Informative) Ground Loop Test
References
