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GB/T 16895.32-2021: Low voltage electrical installations - Part 7-712: Requirements for special installations or locations - Solar photovoltaic (PV) power supply systems
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Low voltage electrical installations - Part 7-712: Requirements for special installations or locations - Solar photovoltaic (PV) power supply systems
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GB/T 16895.32-2021
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| GB/T 16895.32-2008 | English | 439 |
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Electrical installations of buildings -- Part 7-712: Requirements for special installations or locations -- Solar photovoltaic (PV) power supply systems
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GB/T 16895.32-2008
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PDF similar to GB/T 16895.32-2021
Basic data | Standard ID | GB/T 16895.32-2021 (GB/T16895.32-2021) | | Description (Translated English) | Low voltage electrical installations - Part 7-712: Requirements for special installations or locations - Solar photovoltaic (PV) power supply systems | | Sector / Industry | National Standard (Recommended) | | Classification of Chinese Standard | F12;P63 | | Word Count Estimation | 58,563 | | Issuing agency(ies) | State Administration for Market Regulation, China National Standardization Administration | GB/T 16895.32-2021: Low voltage electrical installations - Part 7-712: Requirements for special installations or locations - Solar photovoltaic (PV) power supply systems
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Low voltage electrical installations-Part 7-712.Requirements for special installations or locations-Solar photovoltaic (PV) power supply systems
ICS 27.160;29.020;91.140.50
F12;P63
National Standards of People's Republic of China
Replace GB/T 16895.32-2008
Part 7-712 of low-voltage electrical installations.
Requirements for special installations or places
Solar photovoltaic (PV) power system
(IEC 60364-7-712.2017, IDT)
Released on 2021-04-30
2021-11-01 implementation
State Administration of Market Supervision and Administration
Issued by the National Standardization Management Committee
Table of contents
Preface Ⅴ
Introduction Ⅶ
712 Solar Photovoltaic (PV) Power Supply Unit 1
712.1 Scope 1
712.2 Normative references 1
712.3 Terms and Definitions 3
712.31 Purpose, power supply and structure 7
712.4 Safety protection 14
712.41 Protection against electric shock 14
712.410 Introduction 14
712.412 Protective measures. double or reinforced insulation 14
712.414 Protective measures. use SELV and PELV extra low voltage 14
712.42 Protection against thermal effects 15
712.421 Protection against fire caused by electrical equipment 15
712.43 Protection against overcurrent 16
712.432 Protection of electrical characteristics 16
712.433 Protection against overload 16
712.434 Protection against short-circuit current 20
712.44 Protection against voltage interference and electromagnetic interference 20
712.443 Protection against atmospheric or operating transient overvoltage 20
712.444 Measures to prevent electromagnetic influence 21
712.5 Selection and installation of electrical equipment 21
712.51 General rules 21
712.511 Compliance with standards 21
712.512 Working conditions and external influences 21
712.513 Ease of maintenance 22
712.514 Identification 22
712.515 Prevention of mutual adverse effects 24
712.52 Wiring system 25
712.521 Wiring system type 25
712.522 Selection and installation of cabling systems involving external influences 27
712.523 current carrying capacity 27
712.524 Cross-sectional area of conductor 28
712.525 Voltage drop in user device 29
712.526 Electrical connection 29
712.527 Selection and installation of wiring systems to reduce the spread of fire 30
712.528 Distance between wiring system and other service facilities 30
712.529 Wiring system selection and installation involving maintainability (including cleaning) 30
712.530 Isolation, switching and control 30
712.531 Prevent indirect contact (fault protection) electrical appliances with automatic cut-off of power supply 30
712.532 Appliances to prevent thermal effects 33
712.533 Protective appliances to prevent overcurrent 33
712.534 Protective appliances to prevent transient overvoltage 34
712.536 Isolation and switch 36
712.54 Grounding configuration and protective conductor 37
712.542 Grounding configuration 37
712.55 Other equipment 37
712.6 Inspection and Testing 38
Appendix A (informative appendix) PV installation information 39
Appendix B (Normative Appendix) Calculation of UOCMAX and ISCMAX 42
Appendix C (informative appendix) Examples of marking 43
Appendix D (informative appendix) Isolating diode 44
Appendix E (informative appendix) Arc fault detection and interruption in PV square array 47
References 48
Figure 712.1 General functional configuration of PV installation 7
Figure 712.2 PV square matrix diagram---single string example 8
Figure 712.3 PV square matrix diagram---multi-group series-parallel example 9
Figure 712.4 PV square matrix diagram---several sub-square arrays that make up the square matrix are multiple sets of series and parallel connections 10
Figure 712.5 Use PV square matrix 11 with multiple MPPT DC input PCE
Figure 712.6 Use a PV square array with multiple DC inputs PCE (each input is connected in parallel on the common DC bus inside the PCE)
Figure 712.7 Example of PV array where strings are grouped and each group is protected by an overload protection appliance 18
Figure 712.8 An example of a logo indicating the presence of PV installations on a building 23
Figure 712.9 Example of a cable with reinforced protection 25
Figure 712.10 PV string wiring with minimum loop area 27
Figure A.712.1 Single string PV square array 39
Figure A.712.2 Multi-group series-parallel PV square array 40
Figure A.712.3 The ungrounded PV array is connected to the AC side through a PCE with a built-in transformer 41
Figure A.712.4 The ungrounded PV array is connected to the AC side through a PCE without a transformer 41
Figure A.712.5 The grounded PV square array is connected to the AC side through the PCE containing the transformer 41
Figure A.712.6 The grounded PV array is connected to the AC side through a PCE without a transformer and a separate transformer 41
Figure C.712.1 Example of the required symbols on the PV square matrix combiner box (712.514.102) 43
Figure C.712.2 Example of marking the PV switchboard symbol on a building 43
Figure D.712.1 The role of the isolation diode in the case of a short circuit in the PV string 44
Figure D.712.2 The role of the isolation diode when an insulation fault occurs in a PV installation with a grounded DC negative side 45
Figure D.712.3 The role of the isolation diode in the event of a fault in a PV installation with a grounded DC positive side 45
Figure E.712.1 Examples of arc types in PV square array 47
Table 712.1 Calculation of critical length Lcrit 20
Table 712.2 Minimum current rating of the circuit 28
Table 712.3 Requirements for different system types based on PCE isolation and PV square array functional grounding 30
Table 712.4 Minimum insulation resistance threshold for ground insulation fault detection 31
Table 712.5 Response time limit for sudden change of residual current 32
Table 712.6 The rated current of the automatic disconnector in the functional grounding conductor 33
Table 712.7 Impulse withstand voltage Uw 34 without relevant information
Table 712.8 Breaking appliances required in PV square array device 36
Table A.712.1 PV DC configuration 40
Part 7-712 of low-voltage electrical installations.
Requirements for special installations or places
Solar photovoltaic (PV) power system
712 Solar Photovoltaic (PV) Power Supply Unit
Note. "PV" is the abbreviation of the English word "Photovoltaic", which means "photovoltaic". In this section, "photovoltaic device" is abbreviated as "PV device".
712.1 Scope
This part of GB/T 16895 is applicable to PV system electrical installations that supply power to electrical installations in whole or in part.
Like any other equipment, for the equipment in the PV installation, only its choice and application in the installation are involved.
The PV installation starts from a single PV module provided by the manufacturer or a group of PV modules connected in series with cables, until the user installation or municipal
The part of the power supply point (common connection point).
The requirements of this section apply to.
---PV installations not connected to the public power distribution system;
---PV devices connected to the public power distribution system grid-connected;
---PV installation as an alternative to the public power distribution system;
--- Appropriate combination of the above.
This section does not include specific installation requirements for battery packs or other energy storage equipment.
Note 1.Additional requirements for PV devices equipped with battery energy storage on the DC side are under consideration.
Note 2.This section includes the protection requirements for PV arrays due to the use of battery packs in PV installations.
Additional requirements for the relevant voltage and current ratings, switches and protective appliances applicable to the use of DC-DC converter systems are under consideration.
In addition to the hazards caused by traditional AC power devices, DC systems, especially PV arrays, will also bring some hazards. Included in small
A situation in which an arc is generated and maintained under normal operating current conditions. The purpose of this part is to solve the design and safety requirements due to the characteristics of PV installations.
All requirements.
However, the safety requirements for grid-connected PV installations in this part mainly depend on the PV array and comply with IEC 62109-1 and
Power Conversion Equipment (PCE) required by IEC 62109-2.
712.2 Normative references
The following documents are indispensable for the application of this document. For dated reference documents, only the dated version applies to this article
Pieces. For undated reference documents, the latest version (including all amendments) is applicable to this document.
GB/T 16895.21-2011 Low-voltage electrical installations Part 4-41.Safety protection and electric shock protection (IEC 60364-4-41.
2005, IDT)
IEC 60228 Conductors of insulated cables
IEC 60269-6 Low-voltage fuses Part 6.Supplementary requirements for fuse-links for the protection of solar photovoltaic systems (Low-voltage
fuses-Part 6.Supplementaryrequirementsforfuse-linksfortheprotectionofsolarphotovoltaicener-
gysystems)
IEC 60332-1-2 Tests for electric and optical cables under burning conditions Part 1-2.Vertical burning test for single insulated wires and cables
1kW premixed flame method test process (Testsonelectricandopticalfibrecablesunderfireconditions-Part
1-2.Testforverticalflamepropagationforasingleinsulatedwireorcable-Procedurefor1kWpre-
712.31.101.1.3.2 Each input has its own PCE with Maximum Power Point Tracking (MPPT)
If each input circuit of the PCE provides independent MPPT control, the anti-overcurrent of each part of the square array connected to these input circuits
Protection should consider feedback current.
Each PV section connected to the input circuit (see Figure 712.5) can be treated as a separate PV square array. Should be set in each PV phalanx
Isolation switch to provide isolation from PCE. The isolation switch of the PV square array can be integrated into an electrical appliance for normal mechanical operation.
712.31.101.1.3.3 PCE with multiple inputs (each input circuit is connected in parallel inside the PCE)
If the input circuit of the PCE is connected in parallel to the common DC bus in the PCE, the PV part connected to each input circuit (see
Figure 712.6) is regarded as a sub-square, and all these PV parts belong to a complete PV square. Should be set for each PV sub-array
Isolation switch to provide isolation from PCE. This isolation function can also be provided by a shared PV square array isolation switch.
712.31.101.1.3.4 Series and parallel configuration
All PV strings connected in parallel in the square array should have the same technical characteristics, and each string should be connected in series with the same number of PV modules (see Figure 712.2~
Figure 712.4), unless these components are individually set for MPPT tracking. In addition, all PV modules connected in parallel in the PV array should have similar
Rated electrical performance, including short-circuit current, open circuit voltage, maximum power current, maximum power voltage and rated power (under standard test conditions),
Unless these components are individually set up for MPPT tracking.
This is a design issue considered by the project implementer, especially when replacing components or retrofitting already built PV installations.
712.31.101.1.3.5 Consideration of the expected failure situation in the PV array
The source of the fault current of any device needs to be confirmed.
Due to the characteristics of batteries, PV devices containing battery packs may have higher expected fault currents.
In a PV installation without a battery pack, the photovoltaic cells (and the PV array formed therefrom) behave like electricity when a low-resistance fault occurs.
Stream source. Therefore, even in the case of a short circuit, the fault current cannot be much larger than the normal full load current.
The fault current depends on the number of strings, the location of the fault, and the irradiance level. Therefore, it is very important to perform short-circuit current detection in the PV square matrix.
difficult. In PV installations, the fault current lower than the operating current of the protective device may still form an arc.
712.31.101.1.3.6 performance issues
The performance of the PV array may be affected by many factors, including but not limited to.
---Overall or partial occlusion;
---The temperature rises;
---Cable voltage drop;
---Dust, soil, bird droppings, snow, industrial pollution, etc. cause dirt on the surface of the square array;
---PV module direction;
---PV module attenuation.
The location of the PV array should be carefully selected.The shadows formed by nearby trees and buildings may be on the PV side at some time of the day.
In battle.
It is important to minimize any shadows as much as possible. Keep in mind that even a small shadow on the square will significantly limit its performance.
In 712.515.101, the performance degradation due to temperature rise and the need for good ventilation are stated. It should be paid attention to as much as possible.
The components remain cool.
In the design process, the selection of the cables in the square array and the cables connected from the square array to the application circuit all affect the current carrying conditions of these cables.
Voltage drop. This is particularly important in PV installations with low output voltage and high output current. Under the maximum load condition, the most
The voltage drop from the remote component to the input terminal of the application circuit should not exceed 3% of the maximum power point voltage of the PV matrix.
Dust, soil, bird droppings, snow and other pollution on the surface of PV modules can significantly reduce the output of the square array. Arrangements should be made to
Clean these components regularly in case of heavy contamination.
712.4 Safety protection
712.4.101 Overview
See Appendix B for the calculation methods of UOCMAX and ISCMAX.
712.4.102 Functional grounding (FE) of the live part on the DC side
Due to functional reasons, some PV module technologies need to ground the live parts.
If a transformer with electrical isolation between the primary and secondary windings is used to form the most basic simple separation between the AC side and the DC side, it is allowed
Allow the functional grounding of the live part of the DC side of the PCE. The transformer can be located inside or outside the PCE. But should not connect the PCE
The transformer winding is grounded, and the PCE should meet this requirement.
The functional grounding of the live part should be implemented at a single point on the DC side, near the DC input end of the PCE or at the PCE itself.
The ground is preferably located between the disconnecting device and the DC terminal of the photovoltaic PCE.
At the same time, it should meet the requirements of 712.421.101.2.3.
Cables used for functional grounding shall not be marked with a combination of green and yellow colors. Pink should be used.
712.41 Protection against electric shock
712.410 Introduction
712.410.101
Even if the grid is disconnected on the AC side or the PCE is disconnected on the DC side, the PV equipment on the DC side should be considered live.
712.410.3.5
The barriers described in Appendix B of GB/T 16895.21-2011 and the protective measures placed outside the reach of the arm should not be used.
712.410.3.6
The following protective measures described in Appendix C of GB/T 16895.21-2011 should not be used.
--- Non-conductive places;
---Ungrounded local equipotential bonding;
---Electrical separation for supplying power to more than one electrical equipment.
712.410.102 One of the following protective measures should be used on the DC side.
---Double or reinforced insulation;
---Safety Extra Low Voltage (SELV) or Protective Extra Low Voltage (PELV).
712.412 Protective measures. double or reinforced insulation
712.412.101 The equipment used on the DC side such as PV modules, distribution boxes or distribution cabinets shall be Class II insulation specified in IEC 61140
Or equivalently insulated.
712.414 Protective measures. use SELV and PELV extra low voltage
712.414.101 If SELV and PELV protection measures are used on the DC side, UOCMAX should not exceed DC 60V.
712.414.102 The maximum voltage UOCMAX of the PV square matrix should be considered as a smooth DC voltage.
712.42 Protection against thermal effects
712.42.101 Fire safety of PV installations
The national or local fire protection requirements shall be complied with.
712.421 Protection against fire caused by electrical equipment
Note. Refer to Appendix E for arc fault detection and interruption in the PV array.
712.421.101 Protection against the effects of insulation faults
712.421.101.1 Protection against the effects of insulation failures in the PCE or when there is no simple separation on the AC side
712.421.101.1.1 Functional grounding of live parts on the DC side is not allowed.
712.421.101.1.2 Insulation failure occurs on the DC side, should.
---The AC side of the PCE is automatically disconnected, or;
---The faulty part of the PV array is automatically disconnected in the PCE.
Note 1.Automatic disconnection can be implemented by PCE, see IEC 62109 (all parts).
Note 2.Automatic disconnection can also be implemented by RCD.
712.421.101.1.3 When an insulation fault occurs on the DC side, an alarm shall be automatically issued (see 712.531.3.101.3).
Note. If the PCE detects an insulation failure, according to the provisions of IEC 62109 (all parts), the alarm is issued by the PCE.
712.421.101.2 Protection against the effects of insulation failure when there is a simple separation in the PCE or on the AC side
712.421.101.2.1 allows the functional grounding of the live part of the DC side.
712.421.101.2.2 If the live part of the DC side is not functionally grounded, an insulation monitoring device (IMD) should be installed or the same
Other electrical appliances that monitor the performance.
Note. An inverter that meets the requirements of IEC 62109 (all parts) can be used to provide this function.
712.421.101.2.3 In addition to the application in the next paragraph, it shall provide a
712.532.102 requires an electrical appliance or electrical appliance combination that interrupts the current in the functional grounding conductor when an insulation fault occurs on the DC side. In addition, the root
According to the requirements of 712.421.101.2.4, the appliance (or appliance combination) should also report to the police.
When the functional ground is implemented by the resistor R that meets the formula (1), the provisions of the previous paragraph do not apply.
R ≥
UOCMAX
In
(1)
Where.
In---the current value given in Table 712.6.
Note 1.Due to functional reasons, it may be necessary to turn off the PCE immediately in the event of an insulation failure.
If the live part of the DC side is functionally grounded through a resistor, an insulation monitoring device (IMD) or another type that can provide
Electrical appliances that are also effectively monitored (see 712.531.3).
Note 2.PCE conforming to IEC 62109 (all parts) can be used to provide this function.
712.421.101.2.4 An insulation failure on the DC side should automatically send an alarm (see 712.531.3.101.3).
Note. If an insulation failure is detected by the PCE, the PCE will alarm according to the requirements of IEC 62109 (all parts).
According to the provisions of 411.6.3.1 in GB/T 16895.21-2011, the fault should be eliminated in the shortest possible time.
712.43 Protection against overcurrent
712.430.3 General requirements
712.430.3.101 Overview
The overcurrent in the PV square array may be caused by a fault in the square array line, or it may be caused by a short-circuit fault in the component, combiner box or component line
The current is caused.
PV modules are power sources with limited current, but because they can be connected in parallel or connected to an external power source, they may withstand overcurrent
flow. These overcurrents may be the sum of the following currents.
---Multiple parallel strings;
---A certain type of PCE to which the PV module is connected, and/or;
---External power supply.
712.430.3.102 Requirements for overcurrent protection
The overcurrent protection should be set in accordance with 712.430.3.102~712.433.1.101 and the requirements of the PV module manufacturer.
The overcurrent protection device selected for the PV module and/or its circuit should be when the PV module overcurrent reaches 135% of its rated current,
Maintain reliable operation within 2h.
712.430.3.103 Requirements for string overcurrent protection
If formula (2) is established, string overcurrent protection should be set.
[(Ns-1)×ISCMAX] >IMOD_MAX_OCPR (2)
Where.
Ns---The total number of parallel strings protected by the nearest overcurrent protection appliance.
When using a circuit breaker with overcurrent protection components, this circuit breaker can also provide 712.536.2.101 ~ 712.536.2.103
The required breaking method.
712.430.3.104 Requirements for overcurrent protection of sub-square arrays
If more than two sub-arrays are connected in parallel, the over-current protection of the sub-arrays should be set.
712.432 Protect the characteristics of electrical appliances
712.432.101 The isolation diode used in parallel with the PV string should not be used as an overcurrent protection device.
712.432.102 The overcurrent protection device on the DC side should be a gPV fuse that meets the requirements of IEC 60269-6, or it can be a
Another electrical appliance required by IEC 60947 (all parts) or IEC 60898 (all parts).
Electrical appliances that meet the requirements of IEC 60947 (all parts) and IEC 60898 (all parts) should be of the type suitable for the expected conditions, especially
It should be suitable for working in direct current, reverse current and critical current.
712.433 Protection against overload
712.433.1 Coordination between conductor and overload protection device
712.433.1.101 Selection of overload protection appliances
712.433.1.101.1 Overview
Considering that the Isc of the PV system often runs under the expected climatic conditions exceeding the STC value, it is at 712.433.1.101.2~
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