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GB 7251.6-2015 PDF in English

GB 7251.6-2015 (GB7251.6-2015) PDF English
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GB 7251.6-2015: PDF in English

GB 7251.6-2015
Low-voltage switchgear and controlgear assemblies - Part 6. Busbar trunking systems (busways)
ICS 29.130.20
National Standards of People's Republic of China
Replacing GB 7251.2-2006
Low-voltage switchgear and control equipment
Part 6. busbar trunking systems (busways)
Part 6. Busbartrunkingsystems (busways)
Issued on. 2015-05-15
2016-06-01 implementation
Administration of Quality Supervision, Inspection and Quarantine of People's Republic of China
Standardization Administration of China released
Table of Contents
Introduction Ⅲ
1 Scope 1
2 Normative references 1
3 Terms and definitions 2
4 Symbols and abbreviations 3
5 3 interface characteristics
7 7 conditions of use
8 structural requirements
9 Performance requirements
10 9 Design Verification
11 19 Routine Tests
Appendix 20
Annex C (informative) Specification Table 21
Annex D (informative) design verification 25
Voltage Annex AA (informative) drop across the system 26
Appendix BB (informative) phase conductor properties 27
Annex CC (informative) fault zero sequence impedance 29
Appendix DD (informative) fault loop resistance and reactance 31
The magnetic field near the appendix EE (informative) busbar trunking system determines 33
References 34
101 straight section 10 of the mechanical load test
102 mechanical load test connection points 10
103 flame test verification arrangements baffle busbar trunking unit 19
Figure BB.1 phase conductor characteristic determination 27
Figure CC.1 fault zero sequence impedance is determined 29
Figure DD.1 fault loop resistance and reactance determined 31
Figure EE.1 magnetic field measurement arrangement 33
Table 101 tap unit nominal dispersion coefficient 5
Table 5 Characteristics of phase conductor 102
Table 103 Fault loop characteristics 6
104 Characteristics Table 6 for fault current calculations
Thermal cycle test conditions 105 Table 12
Table C.1 user specifications Table 21
Table D.1 Design Verification 25
Section 6 of this chapter, Chapter 8, Chapter 9, Chapter 10, Chapter 11, Appendix A, Appendix B, Appendix F, Appendix G, Appendix J, Appendix K,
Appendix N mandatory, the rest are recommended.
GB 7251 "Low-voltage switchgear and control equipment" series of standard plans to release the following components.
--- Part 1. General;
--- Part 2. Complete power switching and control equipment;
--- Part 3. by the general staff of the switchboard operator (DBO);
--- Part 4. Particular requirements for construction sites with equipment (ACS); and
--- Part 5. utility grid power distribution equipment;
--- Part 6. busbar trunking systems (busways);
--- Part 7. equipment for specific applications --- such as docks, campgrounds, Market Square, electric vehicle charging stations;
--- Part 10. Guide to the provisions of complete sets of equipment.
This is Part 6 GB 7251's.
This section drafted in accordance with GB/T 1.1-2009 given rules.
This Part replaces GB 7251.2-2006 "Low-voltage switchgear and control equipment Part 2. busbar trunking systems (bus
Groove) special requirements ", compared with GB 7251.2-2006, the main technical changes are as follows.
--- Adjustment GB 7251.1 in part on the structure and technical content;
--- Introduce appropriate new verification methods;
--- Modify resistance, reactance and impedance measurement and calculation of contradictions.
This part is proposed by the China Electrical Equipment Industrial Association.
This part of the National Low-voltage switchgear and control equipment Standardization Technical Committee (SAC/TC266) centralized.
This section is drafted. Tianjin Electric Drive Design Institute Co., Ltd., Tianjin-day electric power distribution Ltd, state-controlled electricity distribution
Equipment Quality Supervision and Inspection Center, Daquan Group Co., Ltd., Yuyao electrical equipment built factory, China Quality Certification Center, Guangzhou radius electricity
Power Copper Co., Ltd., Jiangsu Huapeng Zhi can Electric Co., Ltd., Gansu Electric Apparatus Research Institute, Chengdu Branch Star Electric Power Co.,
Zhenjiang City Product Quality Supervision and Inspection Center, Zhuhai Guangle Power Busway Ltd., Kyrgyzstan Linlong Ding Electric Co., Ltd. Zhenjiang Simon
Picture Line Ltd., Jiangsu Jiangcheng Electric Co.
The main drafters of this section. Wang Yang, Zhang Lei, Cui Jing, Liu Jie, Duan Yi, Sha Wang, Zhang, Pei Jun, Xia Hui Jun, Chen Xin, Chen Jian, Chen Qing Zhou,
Zhang Weimin, INDUSTRIAL ENGINEERING, Xiao Rong, Ding Zhidong, Lei Qinghua, Li Yan, Li Fei, Chen Ting election.
This part of the standard replaces the previous release case.
--- GB 7251.2-1997, GB 7251.2-2006.
Low-voltage switchgear and control equipment
Part 6. busbar trunking systems (busways)
1 Scope
Note 1. Throughout this section, the abbreviation BTS for busbar trunking systems. When it comes to Part 1, the term "equipment" referred to "BTS".
GB 7251 This section specifies the following low-voltage equipment (see 3.101) definition of conditions, construction requirements, technical characteristics and verification
Certification requirements.
--- AC rated voltage not exceeding 1000V, 1500V DC does not exceed the equipment;
--- Equipment and power generation, transmission, distribution, power conversion and control of electric power consumption of the equipment for use;
--- Designed for the special conditions of complete sets of equipment, such as ships, railway and civilian (non-professionals to operate), provided that they meet the relevant special
Statutory requirements;
Note 2. IEC 60092-302 contains marine equipment Supplementary requirements.
--- Equipment for the electrical equipment of machines designed, IEC 60204 contains the complement components constituting the machine complete sets of equipment
Filling requirements.
This section applies to all-time design, manufacture and testing of fully standardized or volume manufacturing equipment.
Production and/or assembly can not the initial manufacturer (see Part 1 3.10.1 and 3.10.2).
This section does not apply to individual devices and self-contained components that conform to their relevant product standards, such as motor starters, fuse open
Off and electronic equipment.
This section does not apply to the rest of 7251 GB in a particular type of equipment, the power rail system GB 13961-2008
EC, GB/T 19215 (all parts) of the cable tray and conduit systems and IEC 61534 (all parts) of a power rail system.
2 Normative references
The following documents for the application of this document is essential. For dated references, only the dated version suitable for use herein
Member. For undated references, the latest edition (including any amendments) applies to this document.
Except as follows, GB 7251.1-2013 of this chapter applies.
GB 7251.1-2013 Low-voltage switchgear and control equipment Part 1. General (IEC 61439-1.2011, IDT)
GB/T 18380.31-2008 and optical fiber cables under fire conditions test (Part 31). vertically mounted bunched wires
Cable vertical flame spread test test equipment (IEC 60332-3-10.2000, IDT)
IEC 60439-2.2000 Low-voltage switchgear and control equipment Part 2. busbar trunking systems (busways) Special
Requirements [Low-voltageswitchgearandcontrolgearassemblies-Part 2. Particularrequirementsforbusbar
trunkingsystems (busways)]
IEC 61786.1998 on measuring human exposure to low frequency magnetic and electric fields - special equipment requirements and measurement guidelines (Meas-
ISO 834-1.1999 Fire resistance tests for structural assemblies - Part 1. General requirements (Fire-resistancetests-
Elementsofbuildingconstruction-Part 1. Generalrequirements)
3 Terms and Definitions
Except as follows, GB 7251.1-2013 of this chapter applies.
Increase definition.
Busbar trunking system busbartrunkingsystems; BTS
Busway busways
For all types of load distribution and control of electrical energy for industrial, commercial and similar applications, the conductors in the form of a closed system equipment.
The conductor system consists of pipes, grooves or similar enclosure of insulating material spacing and supporting the busbars.
[Source revised IEC 60050-441. 1984,441-12-07]
Note 1. See the definition of equipment GB 7251.1-2013 3.1.1.
Note 2. The busbar trunking system by a series of mechanical and electrical components, such as.
--- With or without busbar trunking unit tap means;
--- Commutation, expansion, bending, feed and variable capacitance unit;
--- Tap unit;
--- For communication and/or control of additional conductors.
Note 3. The term "bus" is not set in advance of the conductor geometry, size and area.
Busbar trunking unit busbartrunkingunit; BTU
A unit busbar trunking system. The unit consists of bus, bus support and insulation, housing and other fixtures as well as connecting with the unit
Connector connected components. It also means having a tap-tap device may not have.
NOTE. busbar trunking may have different geometric shapes, such as straight, elbow, T-shaped or cross-shaped.
Busbar trunking channel busbartrunkingrun; BTrun
A plurality of linked units busbar trunking busbar trunking system does not include the tap unit.
With sub-busbar trunking unit busbartrunkingunitwithtap-offfacilities bonding device; BTUwithtap-offfacili-
By the original manufacturer of pre-fabricated units can be mounted tap busbar trunking unit at one or more points.
Trolley-style tap busbar trunking unit busbartrunkingunitwithtroley-typetap-offfacilities; BTUwith
Allow the use of roller-type or trolley-type tap unit busbar trunking units.
Busbar trunking variable capacitance unit busbartrunkingadapterunit; adapterBTU
The same system is used to connect different models or different rated current of both units of the busbar trunking unit.
Busbar trunking thermal expansion unit busbartrunkingthermalexpansionunit; thermalexpansionBTU
Allow due to thermal expansion of the busbar trunking system axial channel has a certain amount of movement of the busbar trunking unit.
Note. This term does not default which allow the mobile part, for example. conductor or conductors within the housing and the housing at the same time.
Busbar trunking commutation unit busbartrunkingphasetranspositionunit; phasetranspositionBTU
For changing the phase conductors are arranged corresponding to the position or change in position of balance of anti-phase (eg. L1-L2-L3-N is converted into N-L3-L2-L1)
The busbar trunking units.
Busbar trunking bending unit flexblebusbartrunkingunit; flexbleBTU
Conductor and the housing is designed to allow installation into the specified direction of busbar trunking units.
Busbar trunking feeding unit busbartrunkingfeederunit; feederBTU
Used as incoming unit of busbar trunking units.
Note. The definition of the line unit, see GB 7251.1-2013 3.1.9.
Tap-tap-offunit unit
Busbar trunking tap unit from the power outlet unit, which can be fixed or mobile.
Note 1. The definition of qualifying units, fixed parts and mobile parts of 3.1.10,3.2.1 see GB 7251.1-2013 and 3.2.2.
Note 2. Plug-tap unit can be manually connected and disconnected a mobile tap unit (see 8.5.2).
Busbartrunkingunitforbuildingmovements busbar trunking unit for moving the building structure; BTUfor
It allows building due to thermal expansion, contraction and/or bending movement of the busbar trunking unit.
Busbar trunking flame baffle unit busbartrunkingfirebarrierunit; firebarrierBTU
Under fire conditions, for within the specified time to prevent flame penetration busbar trunking structures spread unit or a part thereof.
4 Symbols and Abbreviations
Except as follows, GB 7251.1-2013 of this chapter applies.
Symbols/Abbreviations Terms reg number
Temperature coefficient k1A busbar trunking system 5.3.1
Temperature coefficient k1c circuit 5.3.2
Installation factor k2c circuit 5.3.2
R, X, Z phase conductor and the faulty circuit characteristics 5.101
5 Interface Features
Except as follows, GB 7251.1-2013 of this chapter applies.
5.1 General
Performance busbar trunking system shall ensure that the connected circuits are compatible rating and installation conditions, and by busbar trunking system manufacturer
5.2 to 5.6 in accordance with the guidelines and 5.101 ~ 5.102 determined will be described.
Specification of a list of information in Appendix C to help users and busbar trunking system manufacturer for this purpose, regardless of whether the user is.
--- Choose performance to meet the requirements and meet the requirements of this part of the catalog; and/or
--- Specific agreements with manufacturers.
Note. Appendix C is also associated with the Article 6 and 7 of the topic.
In some cases, the information provided by the manufacturer busbar trunking system can replace the agreement.
5.2.4 Rated impulse withstand voltage (Uimp) (complete sets of equipment)
Instead of comments.
Note. Unless otherwise specified, in accordance with GB 7251.1-2013 given in Table G.1 overvoltage category Ⅳ (installation class origin) or Ⅲ (distribution circuit level)
Select the rated impulse withstand voltage.
5.3.1 Equipment rated current (InA)
When the busbar trunking system is not at one end of the channel is provided with a bus trunk line unit (for example. Note. 4 line unit is not installed in the busbar trunking system
End, or more than one incoming unit), rated current shall be agreed upon between the user and manufacturer.
Rated current applied to a specific direction of installation (see 5.3.2). For horizontal busbar trunking system in the short vertical portion (for example, less than
3m length), the impact of the mounting direction is negligible.
Busbar trunking system manufacturer may indicate different air temperature rated current of busbar trunking system, for example, by the following formula.
I'nA = k1AInA
k1A --- temperature coefficient, the ambient air temperature is 35 ℃ equal to 1.
Important harmonic current situation and, if necessary, should be made to reach a special agreement attenuation coefficient.
5.3.2 a circuit rated current (Inc)
Each circuit (ie incoming unit, busbar trunking units, tap units, outgoing circuit) rated current equal to or higher than the assumed load.
For tap-units with more than one main outlet circuit, see also 5.4.
Rated current is applied to a particular installation. Installation conditions may include the following directions and locations.
a) direction
Direction may be horizontal or vertical.
Unless otherwise specified, the reference direction is horizontal.
b) Location
For example, the position may be an upper layer along the direction of the busbar trunking channel layer or consistent direction, and/or tapping unit busbar trunking unit
Or top.
Where applicable, the busbar trunking system manufacturer may indicate different air temperature and/or installation conditions of different nominal current by the following formula.
I'nc = k1ck2cInc
k1c --- temperature coefficient, the ambient air temperature is 35 ℃ equal to 1;
k2c --- installation factor, the reference installation conditions equal to 1.
Important harmonic current situation and, if necessary, should be made to reach a special agreement attenuation coefficient.
5.4 Rated dispersion coefficient (RDF)
For the entire busbar trunking system, unless otherwise specified, the nominal dispersion coefficients (see GB 7251.1-2013 of 3.8.11) shall be equal to 1, or
Is within the busbar trunking busbar trunking channels and feeding unit rated current limit, all units can be simultaneously tap their full continuous load
Unit rated current.
Note 1. This is due to the thermal influence of the tap unit between negligible.
For tap-units with more than one main terminal of the circuit, these circuits should be able to tap unit within the rated current limit, and even
They continued load rated current multiplied by the nominal dispersion coefficients. Unless otherwise specified, the tap unit shall be equal to the nominal dispersion coefficient table
Given the value 101.
Table 101 tap unit nominal dispersion coefficients
The main terminal number of circuits rated dispersion coefficient
2 and 3 0.9
4 and 5 0.8
6-9 0.7
10 (and above) 0.6
Busbar trunking system at rated current (InA) runs, dispersion coefficient can be rated.
Note 2. The nominal dispersion coefficients suggest that in practice more functional units are not simultaneously at full load or intermittent loads.
Note 3. The outgoing circuit can be assumed that the load is a steady continuous current or a variable current thermal equivalent.
5.6 Other Features
Terms e) Revision.
e) static busbar trunking systems;
Terms j) Revision.
j) enclosed busbar trunking systems;
aa) the ability to withstand the mechanical loads, normal or overloaded (see 8.1.101);
bb) if applicable, to prevent the spread of flame (see 9.101);
cc) if applicable, the building structure fire (see 9.102).
Increase Article.
5.101 phase conductor and the fault loop feature
Note 1. For the rated current is less than 100A busbar trunking systems, reactance is negligible.
Calculate the voltage drop (see Informative Appendix AA) according to Table 102, R and X are used.
Table 102 phase conductor properties
With average characteristics Conductor
Rated current and rated frequency fn Inc
Ω per meter length
--- Ambient air temperature is 35 ℃,
--- Conductor temperature is 20 ℃
Reactance (independent of temperature) X
Positive and negative sequence impedance
--- Ambient air temperature is 35 ℃,
--- Conductor temperature is 20 ℃
Z = Z (1) = Z (2)
Z20 = Z (1) 20 = Z (2) 20
All phase conductors characteristics can be determined in accordance with Appendix BB
Table 102 R20 and X table 103 in the fault loop resistance and reactance, which is the total phase conductors and circuit resistance and reactance with
To calculate the fault current through the impedance method (see Table 104).
Table 102 Table 103 Z and Z20 fault zero sequence impedance, which is the total loop phase conductor and zero sequence impedance for by
Said component method (see table 104) to calculate fault current.
Note 2. The fault current reaches a minimum value at the maximum impedance value; this is considered normal at the highest ambient air temperature is 35 ℃, busbar trunking unit
Inc in operation, so that the conductor temperature (35 Δθ) ℃ occurs, where Δθ is measured in accordance with 10.10 average stable temperature.
On the contrary, the fault current reaches the maximum value at the lowest impedance value; this is considered not running in busbar trunking unit, resulting in a conductor temperature
It occurred at 20 ℃, when a short circuit is closed.
Fault loop characteristic table 103
Fault loop characteristics Average
Rated frequency fn when
Ω per meter length
Phase - Phase - neutral phase -PEN phase -PE
Zero sequence impedance
--- In the ambient air temperature is 35 ℃,
--- In the conductor temperature is 20 ℃,
Z (0) bphN
Z (0) b20phN
Z (0) bphPEN
Z (0) b20phPEN
Z (0) bphPE
Z (0) b20phPE
--- In the ambient air temperature is 35 ℃,
--- In the conductor temperature is 20 ℃,
Reactance (temperature-independent) Xbphph XbphN XbphPEN XbphPE
Zero-sequence fault loop impedance can be determined in accordance with Appendix CC.
Fault loop resistance and reactance may be determined in accordance with Appendix DD.
Table 104 is used to calculate the characteristics of the fault current
Fault current impedance method of symmetrical components
The maximum short-circuit current
---Phase 3
Between phase and phase ---
--- Between phase and neutral line
R20, X
Rb20phph, Xbphph
Rb20phN, XbphN
Z20 and Z (0) 20phN
The minimum short-circuit current
Between phase and phase ---
--- Between phase and neutral line
Rbphph, Xbphph
RbphN, XbphN
Z and Z (0) phN
(Between phase and PE (N)) ground fault currents RbphPE (N), XbphPE (N) Z and Z (0) phPE (N)
Note 3. The symmetrical components respectively Modulo fault circuit positive, negative and zero sequence impedance (see IEC 60909-0) sum basis, similar to the impedance method
Respectively Modulo fault loop resistance and reactance sum basis.
5.102 Field
The strength of busbar trunking channel frequency magnetic field close to the busbar trunking system can be provided by the manufacturer.
NOTE. rapidly reducing the magnetic field is a function of distance.
Measurement and calculation methods for busbar trunking systems around the magnetic field modulus is given in Appendix EE.
6 Information
Except as follows, GB 7251.1-2013 of this chapter applies.
6.1 Equipment identification
After the increase in the first paragraph.
It should be placed a plate on each busbar trunking unit near one end and each tap unit.
d) GB 7251.6.
7 Conditions
Except as follows, GB 7251.1-2013 of this chapter applies.
7.2 Special conditions of use
aa) exposure to specific mechanical loads, such as lighting equipment, additional cable, cable stent;
bb) with high repeatability over-current applications such as resistance welding;
cc) highly sensitive IT equipment installed nearby, such as high-speed data network, radio equipment, monitors and other working conditions;
dd) require specific performance applications, such as circuit integrity within a specific time under fire conditions.
8 structural requirements
Except as follows, GB 7251.1-2013 of this chapter applies.
8.1.5 Mechanical strength
After the increase in the last paragraph.
With trolley busbar trunking systems should be able to tap means continuous moving back and forth along the conductor busbar trunking 10,000 channels, which slide
Movable contact should carry the rated current at the rated voltage. In exchange, the load power factor shall be between 0.75 and 0.8.
10.13 based on experiments to verify this requirement.
Increase Article.
Ability to withstand the mechanical loads 8.1.101
Busbar trunking systems installed horizontally, in use, it should be able to withstand 5.6aa) normal or heavy mechanical load requirements.
In addition to the normal mechanical load weight busbar trunking system, further comprising a non-self-supporting member fixed feeding unit and the tap unit
Heavy mechanical loads include additional loads, such as the weight of personnel.
NOTE. This description is not meant busbar trunking system is a channel.
The necessary mechanical properties of the material by the number of the choice of material thickness, shape and/or through a fixed point and the initial manufacturers label
Position to obtain.
10.2.101 based testing to verify this requirement.
Plug-in capability 8.1.102 tap unit withstand heat changes
When the intermittent load, due to the offset spring member produces contact pressure tap plug-in unit, it should be able to withstand changes in temperature cause
Mechanical suppression.
Note. For this requirement, not a spring disc spring member.
10.2.102 based testing to verify this requirement.
8.2.1 Protection against mechanical impacts
When the initial manufacturer in accordance with GB/T 20138 in the IK code illustrates the degree of protection against mechanical impacts, busbar trunking systems should be designed
To withstand GB/T 20138 in the IK Code (see 10.2.6) in the test.
After the increase in the first paragraph.
Supplementary insulation clearances shall be not less than the predetermined value of the underlying insulation. Reinforced insulation clearances size should be higher than the rated impulse voltage
Predetermined value of the underlying insulating a high level (see Table 1 GB 7251.1-2013).
8.3.3 creepage distance
After the increase in the third paragraph.
Supplementary insulation creepage distance of not less than a predetermined value based insulation. Reinforced insulation creepage distance insulation should be the basis of two predetermined values
Times (see Table 2 GB 7251.1-2013). protected from the consequences of an external circuit conductor requirements busbar trunking system failure caused by power provided
After the increase in the last paragraph.
In the busbar trunking system with sliding-touch tap device, the assembly should take precautions to ensure that the tap unit exposed conductive parts
Between the exposed conductive parts and the fixed and permanent good conductivity, especially when the protection circuit case fixed unit is installed in a
8.5.2 Movable member
Movable parts together with a device which ensures that only can be removed and inserted after its main circuit and the load is disconnected.
NOTE. a tap unit is a sub-clause 3.2.2 and mobile components defined in GB 7251.1-2013, as specified by the manufacturer.
8.5.5 accessibility
GB 7251.1-2013 sub-clause does not apply.
Increase in sub-clause.
8.6.101 proper connection between the busbar trunking systems unit
Busbar trunking unit should be designed to ensure that the composition of a neighboring busbar trunking systems (power supply circuit, auxiliary circuit and communication, PE) of
Proper connection between the conductor units, this requirement can be achieved by the correct identification of each connector.
Busbar trunking units and tap unit should be designed to ensure that it is properly connected between the conductors (power supply circuit, auxiliary circuit and communication, PE)
Then, this requirement shall be inserted by interlocking (see GB 7251.1-2013 3.2.5) to reach.
9 Performance requirements
Except as follows, GB 7251.1-2013 of this chapter applies.
9.2 temperature limit
Replacing GB 7251.1-2013 Table 6 footnote d.
d Unless otherwise specified, under the cover plate and the housing accessible in normal operation but does not require contact with the case, the allowable temperature rise limit of the metal surface to improve the 25K,
Limit temperature insulating material surface to improve 15K.
Increase in sub-clause.
9.101 prevent the spread of flame
When the fire source is removed, the non-flame spread busbar trunking system should not be ignited, or if ignited should not continue to burn.
The flame spread according to the tests of 10.101.
Fire in building structures 9.102
If so, the flame baffle busbar trunking unit should be designed under fire conditions, within the specified time to prevent the spread of flame, this time building bus
Trunk system vertically or horizontally through the building (for example, a wall or ground).
Where applicable, the following preferred time. 60min, 90min, 120min, 180min or 240min.
Additional components can be realized.
Based on the 10.102 fire test to test.
10 Design Verification
Except as follows, GB 7251.1-2013 of this chapter applies.
10.1 General
Instead of the second paragraph.
When the busbar trunking system has been IEC 60439-2.2000 in the test and the test results meet the requirements of this section, these requirements
Verify that need not be repeated.
Performance b) increase at the end.
10.101 prevent the spread of flame;
The fire 10.102 building structures.
10.2.6 mechanical collision
Busbar trunking system shall be in accordance with GB/T 20138 test.
After the test, busbar trunking systems should continue to provide IP code and dielectric strength. If applicable, should be able to move and re-install mobile cover plate
And the tap unit and a switch door.
Increase in sub-clause.
Ability to withstand the mechanical loads 10.2.101
Test procedure straight busbar trunking unit
The first test should be in a straight busbar trunking units, the busbar trunking unit is placed properly supported at two points like as two
Point distance D. Initial D is the maximum distance between the two support points specified by the manufacturer. Location and form of the support member by the initial manufacturer of Regulation
Fixed, see Figure 101.
101 straight unit mechanical load test
Not led to a mass M is contained in an added edge width equal to the width of the busbar trunking system side of the square rigid p......
Source: Above contents are excerpted from the PDF -- translated/reviewed by: www.chinesestandard.net / Wayne Zheng et al.