GB/T 45119-2024 Technical requirement for insulation monitoring of low voltage power system in power plants and substations
1 Scope
This document specifies the basic requirements, monitoring requirements, installation acceptance, operation and maintenance requirements for insulation monitoring of low voltage power system in power plants and substations.
This document is applicable to the design, selection, installation and use of insulation monitoring of low voltage AC and DC power systems in power projects such as power plants, substations and converter stations.
2 Normative references
The following documents contain provisions which, through reference in this text, constitute provisions 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/T 2423.1-2008 Environmental testing for electric and electronic products - Part 2: Test methods - Tests A: Cold
GB/T 2423.2-2008 Environmental testing for electric and electronic products - Part 2: Test methods - Tests B: Dry heat
GB/T 2423.5-2019 Environmental testing - Part 2: Test methods - Test Ea and guidance: Shock
GB/T 2423.10-2019 Environmental testing - Part 2: Test methods - Test Fc: Vibration (sinusoidal)
GB/T 2900.1 Electrotechnical terminology - Fundamental terms
GB/T 2900.33 Electrotechnical terminology - Power electronics
GB/T 17626.2 Electromagnetic compatibility - Testing and measurement techniques - Electrostatic discharge immunity test
GB/T 17626.3 Electromagnetic compatibility - Testing and measurement techniques - Part 3: Radiated, radio-frequency, electromagnetic field immunity test
GB/T 17626.4 Electromagnetic compatibility - Testing and measurement techniques - Electrical fast transient/burst immunity test
GB/T 17626.5 Electromagnetic compatibility - Testing and measurement techniques - Surge immunity test
GB/T 17626.6 Electromagnetic compatibility - Testing and measurement techniques - Immunity to conducted disturbances, induced by radio-frequency fields
GB/T 17626.8 Electromagnetic compatibility - Testing and measurement techniques - Power frequency magnetic field immunity test
GB/T 17626.10 Electromagnetic compatibility - Testing and measurement techniques - Damped oscillatory magnetic field immunity test
GB/T 17626.18 Electromagnetic compatibility - Testing and measurement techniques - Damped oscillatory wave immunity test
DL/T 860 (All parts) Communication networks and system for power utility automation
3 Terms and definitions
For the purposes of this document, the terms and definitions given in GB/T 2900.1, GB/T 2900.33 and GB/T 4365 and the following apply.
3.1
insulation monitoring
monitoring and measuring the insulation condition of low voltage AC and DC power supply system bus and branch circuit to ground
3.2
grounding resistance
insulation resistance to ground of bus or branch of AC and DC power system with ungrounded operation mode
3.3
balancing bridge
(Wheatstone) detection bridge composed of positive and negative equivalent artificial grounding resistance and DC bus grounding resistance. When the bus insulation is good or the resistance value of the grounding resistance is similar, the detection bridge is in balanced state
3.4
unbalanced bridge
invention relates to a bridge composed of (alternately) switched positive and negative artificial grounding resistors, and forms a detection bridge with a balance bridge resistance
3.5
signal injection method
method of inputting known AC, DC, square wave pulse and adaptive pulse signals into the branch, monitoring the corresponding grounding fault signal, detecting the grounding branch or locating the grounding point
4 Basic requirements
4.1 Working environment
Normal working environment of insulation monitoring equipment (hereinafter referred to as "insulation monitoring equipment") of low voltage AC and DC power systems in power plants:
a) The ambient temperature is -5°C~+40°C;
b) The daily average relative humidity shall not exceed 95%, the monthly average relative humidity shall not exceed 90%, and there is no condensation;
c) The altitude is not exceeding 2,000 m;
d) Good ventilation, no explosion hazard, no corrosive gas, and no mold;
e) There is no violent vibration source, no strong electromagnetic interference, and the external magnetic field induction intensity does not exceed 0.5 mT;
f) The horizontal acceleration of vibration does not exceed 0.3 g and the vertical acceleration does not exceed 0.15 g.
Note: Special environmental conditions shall be considered when formulating relevant standards for insulation monitoring equipment.
4.2 Electrical performance
4.2.1 Working power supply
4.2.1.1 The working power supply of insulation monitoring equipment shall be connected from the busbar through the protective appliance. DC input power supply shall be used when monitoring DC system; when monitoring the AC system, AC input power supply or DC input power supply shall be used, and AC and DC power supply shall not be input at the same time.
4.2.1.2 The DC input power supply shall work normally within the following ranges:
a) The voltage range of the 220 V power supply is 176 V~286 V;
b) The voltage range of the 110 V power supply is 88 V~143 V;
c) Ripple coefficient ≤ 5%.
4.2.1.3 The AC input power supply shall work normally within the following ranges:
a) The voltage range of the 380 V power supply is 304 V~456 V;
b) The voltage range of the 220 V power supply is 176 V~264 V;
c) The frequency range is 47.5 Hz~52.5 Hz;
d) The voltage is a sine wave, and the total harmonic content does not exceed 10%.
4.2.2 Dielectric capability
The electrical insulation performance of the following parts of the insulation monitoring equipment shall not be lower than the requirements in Table 1:
a) Between non-electrically connected live circuits;
b) Between each independent live circuit and the ground (metal frame);
c) Between the communication interface and the ground (metal shell of the chassis).
Contents Foreword i 1 Scope 2 Normative references 3 Terms and definitions 4 Basic requirements 4.1 Working environment 4.2 Electrical performance 4.3 Communication and others 5 Test requirements 5.1 Classification 5.2 Functional indexes 5.3 Main way 6 Installation acceptance 6.1 Inspection 6.2 Arrangement 6.3 Acceptance 7 Operation and maintenance 7.1 Operation 7.2 Maintenance Annex A (Normative) Environmental adaptability and electromagnetic compatibility requirements Annex B (Informative) Insulation monitoring of low voltage DC ungrounded systems Annex C (Informative) Insulation monitoring of low voltage AC ungrounded systems Annex D (Informative) Insulation monitoring of low voltage AC grounding systems Bibliography
GB/T 45119-2024 Technical requirement for insulation monitoring of low voltage power system in power plants and substations
1 Scope
This document specifies the basic requirements, monitoring requirements, installation acceptance, operation and maintenance requirements for insulation monitoring of low voltage power system in power plants and substations.
This document is applicable to the design, selection, installation and use of insulation monitoring of low voltage AC and DC power systems in power projects such as power plants, substations and converter stations.
2 Normative references
The following documents contain provisions which, through reference in this text, constitute provisions 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/T 2423.1-2008 Environmental testing for electric and electronic products - Part 2: Test methods - Tests A: Cold
GB/T 2423.2-2008 Environmental testing for electric and electronic products - Part 2: Test methods - Tests B: Dry heat
GB/T 2423.5-2019 Environmental testing - Part 2: Test methods - Test Ea and guidance: Shock
GB/T 2423.10-2019 Environmental testing - Part 2: Test methods - Test Fc: Vibration (sinusoidal)
GB/T 2900.1 Electrotechnical terminology - Fundamental terms
GB/T 2900.33 Electrotechnical terminology - Power electronics
GB/T 4365 Electrotechnical terminology - Electromagnetic compatibility
GB/T 17626.2 Electromagnetic compatibility - Testing and measurement techniques - Electrostatic discharge immunity test
GB/T 17626.3 Electromagnetic compatibility - Testing and measurement techniques - Part 3: Radiated, radio-frequency, electromagnetic field immunity test
GB/T 17626.4 Electromagnetic compatibility - Testing and measurement techniques - Electrical fast transient/burst immunity test
GB/T 17626.5 Electromagnetic compatibility - Testing and measurement techniques - Surge immunity test
GB/T 17626.6 Electromagnetic compatibility - Testing and measurement techniques - Immunity to conducted disturbances, induced by radio-frequency fields
GB/T 17626.8 Electromagnetic compatibility - Testing and measurement techniques - Power frequency magnetic field immunity test
GB/T 17626.10 Electromagnetic compatibility - Testing and measurement techniques - Damped oscillatory magnetic field immunity test
GB/T 17626.18 Electromagnetic compatibility - Testing and measurement techniques - Damped oscillatory wave immunity test
DL/T 860 (All parts) Communication networks and system for power utility automation
3 Terms and definitions
For the purposes of this document, the terms and definitions given in GB/T 2900.1, GB/T 2900.33 and GB/T 4365 and the following apply.
3.1
insulation monitoring
monitoring and measuring the insulation condition of low voltage AC and DC power supply system bus and branch circuit to ground
3.2
grounding resistance
insulation resistance to ground of bus or branch of AC and DC power system with ungrounded operation mode
3.3
balancing bridge
(Wheatstone) detection bridge composed of positive and negative equivalent artificial grounding resistance and DC bus grounding resistance. When the bus insulation is good or the resistance value of the grounding resistance is similar, the detection bridge is in balanced state
3.4
unbalanced bridge
invention relates to a bridge composed of (alternately) switched positive and negative artificial grounding resistors, and forms a detection bridge with a balance bridge resistance
3.5
signal injection method
method of inputting known AC, DC, square wave pulse and adaptive pulse signals into the branch, monitoring the corresponding grounding fault signal, detecting the grounding branch or locating the grounding point
4 Basic requirements
4.1 Working environment
Normal working environment of insulation monitoring equipment (hereinafter referred to as "insulation monitoring equipment") of low voltage AC and DC power systems in power plants:
a) The ambient temperature is -5°C~+40°C;
b) The daily average relative humidity shall not exceed 95%, the monthly average relative humidity shall not exceed 90%, and there is no condensation;
c) The altitude is not exceeding 2,000 m;
d) Good ventilation, no explosion hazard, no corrosive gas, and no mold;
e) There is no violent vibration source, no strong electromagnetic interference, and the external magnetic field induction intensity does not exceed 0.5 mT;
f) The horizontal acceleration of vibration does not exceed 0.3 g and the vertical acceleration does not exceed 0.15 g.
Note: Special environmental conditions shall be considered when formulating relevant standards for insulation monitoring equipment.
4.2 Electrical performance
4.2.1 Working power supply
4.2.1.1 The working power supply of insulation monitoring equipment shall be connected from the busbar through the protective appliance. DC input power supply shall be used when monitoring DC system; when monitoring the AC system, AC input power supply or DC input power supply shall be used, and AC and DC power supply shall not be input at the same time.
4.2.1.2 The DC input power supply shall work normally within the following ranges:
a) The voltage range of the 220 V power supply is 176 V~286 V;
b) The voltage range of the 110 V power supply is 88 V~143 V;
c) Ripple coefficient ≤ 5%.
4.2.1.3 The AC input power supply shall work normally within the following ranges:
a) The voltage range of the 380 V power supply is 304 V~456 V;
b) The voltage range of the 220 V power supply is 176 V~264 V;
c) The frequency range is 47.5 Hz~52.5 Hz;
d) The voltage is a sine wave, and the total harmonic content does not exceed 10%.
4.2.2 Dielectric capability
The electrical insulation performance of the following parts of the insulation monitoring equipment shall not be lower than the requirements in Table 1:
a) Between non-electrically connected live circuits;
b) Between each independent live circuit and the ground (metal frame);
c) Between the communication interface and the ground (metal shell of the chassis).
Contents of GB/T 45119-2024
Contents
Foreword i
1 Scope
2 Normative references
3 Terms and definitions
4 Basic requirements
4.1 Working environment
4.2 Electrical performance
4.3 Communication and others
5 Test requirements
5.1 Classification
5.2 Functional indexes
5.3 Main way
6 Installation acceptance
6.1 Inspection
6.2 Arrangement
6.3 Acceptance
7 Operation and maintenance
7.1 Operation
7.2 Maintenance
Annex A (Normative) Environmental adaptability and electromagnetic compatibility requirements
Annex B (Informative) Insulation monitoring of low voltage DC ungrounded systems
Annex C (Informative) Insulation monitoring of low voltage AC ungrounded systems
Annex D (Informative) Insulation monitoring of low voltage AC grounding systems
Bibliography
