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1、中原工学院毕业设计(论文)译文当今建筑电气设计的几个问题 1 引言工程设计是最主要的基础设施,设计文件是建设的主要依据,设计质量是决定工程质量的第一部分。我国工程质量事故统计资料显示由设计导致的工程质量事故占40.1%,施工引起的占29.3%;其他原因(比如设备和材料的质量等)引起的占30.6%。表明完成对项目质量控制的关键在于设计的质量控制。电气工程也不例外。 2 影响工程质量的几个建筑电气设计问题合格的建筑设计应该满足七个质量特性的要求,即功能性、安全性、经济性、可靠性,可实施性,适应性和时间性。设计单位应该将通过设计评审的设计文件交付施工。实际上,很多交付施工的设计文件都存在缺少或者偏离
2、质量特性要求的缺陷。对电气工程设计质量造成影响的问题主要表现在安全性、可靠性(包括可用性,可靠性、维修性等等)及可实现性的缺失或偏离。以下是对一些最常见的方面进行的探讨。 2.1 设计违反或偏离设计规范的规定,安全性、可信性不执行设计规范是十分常见的。例如,在市政大楼前的广场花园(包括广场绿化园林照明、草坪照明、广场中心声光喷水池)工程提交施工的电气施工图存在以下几个问题:缺乏电气接地保护和等电位连接设计;错误采用tn-c低压配电系统;喷泉没有选用合适防护等级的电气设备和电缆。这样设计与规范规定的安全要求是完全相反的,按图纸施工会留下严重的安全隐患。此前的1999年8月,青岛的一个喷泉曾发生几
3、个人玩水时被电击致死,这是因为设计错误,水下照明和潜水电泵泄漏不没能及时断电所致。监理在施工前审图时发现上述问题,由业主要求设计单位严格按照设计要求修改设计。正确的方法是:户外庭院和喷泉应采用局部tt配电系统或tn-s系统,设置漏电保护(动作电流不应超过30毫安),不允许使用tn-c系统;应该设置完善的接地装置、喷泉应该做等电位连接的设计,而不能只靠从大楼内引出的一根pe干线接地;潜水泵和水下照明应该用潜水电缆配电;0区电气设备应使用1px8防护等级,一区应为1px5等到。另一个例子是低压配电线路民用部分的选择。因为绝大多数的民用电力负荷是单相负荷,三相负载不平衡必然会引起中线通过不平衡电流,
4、随着计算机设备及各种家用电器的发展和普及,低压电网高次谐波污染日益加剧,3次及其奇倍数谐波均构成中性电流。中线过电流并由此引发电气火灾的现象也不断增加。为此,相关设计规范规定三相四线或两相三线配电线路中,当电力负荷大部分为单相负荷、n线或者pen-line截面不应小于相线截面;以气体放电灯为主要负载的电路中、n线截面应不小于相线截面”,我们可以看出,民用建筑配电系统的干线、分支线和支线的导线截面原则上应该选择n线或pen线截面与相线截面相同。然而,监理审图发现依然有大量的民用建筑配电设计仍然在使用80多年前采用的做法,选择n或pen线截面为相线的1 / 2甚至1 / 4到1 / 3。这是最常见
5、的电气设计的安全问题。再如,关于变配电所位置的选择有关的设计规范已经很明确地提出应该考虑“设备吊装和运输方便,这是确保可用性和维修性的基本要求。近年来我们负责监理的许多高层建筑项目,其设置在地下室的变配电所及柴油发电机房的配置多违反了此要求。例如某高层商住楼地下变配电所,它的运输路径是完全冷水机组和地下水箱堵住了。施工安装顺序只能是先将变配电设备安装就位后再安装冷水机组和水箱,而没有考虑运行后变电站设备维修、更换的运输问题,另一个例子是一个高层办公综合楼地下变配电所与机房,设置在一层某会议室底部,地下层既不考虑必要的运输维修通道,也没提供足够宽度能运进设备的门框。当监理审图发现并提出这一问题时
6、,设计单位的回答竟然是:原先的设计意图是从一层会议室处将变配电及发电机设备吊装就位后在浇筑该厅地板。这种意图显然是错的,即使不考虑土建施工可能对已就位的电气设备造成的损害,大楼投入运行后电气设备的维修更换运输只得撬开一层会议室的的地板来解决。须知钢筋混凝土框架结构建筑的合理使用寿命可达50年以上,而变配电设备的使用寿命只有20年或更少,定期或故障维修周期更短。因此,电气设计必须适当的考虑它的运输和维护吊装通道的问题。 2.2 设计的深度不够目前的施工图设计深度达不到建设部建设工程设计文件编制深度规定的要求是非常普遍的,主要是设计文件可实施性方便的缺陷将直接导致施工安装困难或错误。也可能导致欠缺
7、可用性。由于不按要求的深度进行必要的计算和标注,也常常会导致设计文件本身出现很难发现的原则错误将会影响到项目完成的使用。例如,根据深度规定的电力和照明系统图以及相应的设备和材料应该详细说明表中选择的电气设备及材料的型号、名称、规格和数量参数。自改革开放以来,中国的电气产品市场异彩纷呈,国内外各种型号规格的产品琳琅满目,国家不可能对各种电气设备及材料规定统一的型号。设计标明的各种设备及材料的型号规格参数显得尤为重要,这是业主或施工单位进行设备订货及采购的依据。然而近年来,电气设计文件,普遍习惯于只在系统图的设备符号旁边标注该设备的型号或厂家产品编号,以至于设备订货不知所措,常常导致错误。如某项目
8、的电气照明设计,设计者在系统图断路器符号旁只标注了a063m 20a,设备表中也不例外,而没有指定名称和详细参数,建设单位理解为20安培普通断路器,因为找不到这个编号的产品而另行采购了另一种断路器。监理检查核对设备和材料时,原a063m乃是海格公司的一种电磁式漏电断路器的产品编号,额定电流20安培、额定漏电动作电流30毫安。可见原设计中这些回路是应该设有漏电保护的。但设计标注不清造成订购错误。不得不重新采购更换。另一个例子是许多电气施工图中对电缆沟只标注尺寸和走向,对电缆支架及盖板不作任何规定,或只注明“参照xx图集xx页”,实际上国标图集中对任一种尺寸的电缆沟,其电缆支架及盖板的作法都提供了
9、多个方案供设计时选择,设计不选定则施工方难以抉择,常按最低价方案施工。往往并不能满足实际需要,甚至可能引起结算纠纷。 提供另一个电气照明图的例子,按规定主要房间及场所应标注照度标准值,当然也要求设计者进行照度计算并按计算进行灯具配置。然而当前民用建筑电气照明设计中能标注照度标准值并进行照度计算的极少,绝大多数是按房屋开间及功能凭经验布灯。大多照度偏离了国家规定的标准,影响使用功能。比如通过监理审图的某学校电气施工图,经核算照度设计设计达到实验室和教室的值仅为5070勒克斯,不及国家标准(150勒克斯)的一半;某局综合办公大楼中办公室和会议室的照度设计只达到7080勒克斯,计算机房只达到约100
10、h左右。也不及国家规定照度标准值(分别为150h及200k)的一半。 2.3 相关专业设计文件衔接不清楚,没有按照规定协调建设很容易导致施工错误例如目前广泛使用的结构钢筋作为防雷接闪器、引下线和接地与等电位联结装置,电气工程要求连接绘制点、预埋件,说明敷设方法和技术措施(如焊接要求等);并在土建施工图中有相关的预埋件详图及相关的注解与说明。而实际上大多数施工图仅在电气图中有防雷接地图,且标注与说明相当简略,而土建施工图中则常无任何相关的说明与标注。这给工程监理及施工都带来极大困难,若施工单位经验不足则极易导致施工不当的错误。最常见的是接地钢筋网的连接点的错误、漏焊和作为外引接地联结点或检测点预
11、埋件的漏设。尤其是结构转换层,因柱(墙)内主钢筋调整、防雷引下线钢筋错接错焊的情况更易发生。另一个例子是各专业的管道、线路相互撞击,互相矛盾的问题已成为施工图的多发病,很多很多。我们负责监理的几幢建筑物的地下层(包括一个地下车库)的建筑设计,审图时都发现:给排水管道、排气管道与照明灯具和电气管道多处碰撞,多个火灾探测器被通风排烟管道遮挡;只得修改设计再做施工和安装;另一个例子,某住宅小区由于原设计的给排水和电气专业未能协调工程完成才发现几乎每套居室内空调安装处预留的排水管口及穿墙孔和空调电源插座分别位于外窗两侧的墙上,那就是空调安装位置与插座不在一个地方,插座不能用,不得不返工重装。 3 结论
12、设计文件和施工监理是主要依据,设计能否认真执行国家规定,设计文件的深度与相关专业的密切配合问题等等会直接影响到工程质量。近年来,设计质量滑坡现象已成为一个不争的事实 ,如设计市场恶性的竞价,迫使设计单位减少输入以降低成本等等。本文不以探索。上文只从施工和监理的角度提出常见的弊病。这类毛病不是一种慢性的疾病或顽疾,只要设计单位稍微留心,例如组织设计人员认真地学习相关设计规范,加强设计过程管理,注重设计会签和审查,就可以解决。工程监理和工程施工就会受益。本文摘自:the current building several problems in electrical design 1 introdu
13、ction is a leading infrastructure engineering design, design documents are the main basis for the construction, design quality is to determine the quality of the project the first part. my project quality accident statistics show that from the design of the project quality accident causes accounted
14、for 40.1%; construction causes accounted for 29.3%; other reasons (such as equipment and materials quality, etc.) caused by accounting for 30.6%. this shows the implementation of the project quality control is the key to the design quality control. electrical engineering is no exception. 2 affect th
15、e quality of the project electrical design of several buildings qualified architectural design should meet the requirements of seven quality characteristics, namely functionality, security, economy, credibility, can be implemented, adaptability and timeliness. design units through the design of this
16、 assessment should be qualified to deliver the construction design documents. in fact many of the delivery of construction design documents exist, or the lack of quality characteristics deviate from the requirements defects. the impact on the quality of electrical engineering design problems are pri
17、marily manifested in the security, reliability (including the availability, reliability, maintainability, etc.) and can be implemented of missing or deviate from. the following comment on a few of the most common aspects were discussed. 2.1 design in breach of or deviation from the provisions of des
18、ign specifications, safety, credibility with respect to non-implementation of the design specifications are quite common for example, before a city hall square garden (including the square green garden lighting, lawn lighting and sound and light fountain square center) project discretionary electric
19、al construction drawings submitted to the following problems: the absence of electrical protective earthing and equipotential bonding design; wrong use of tn -c low-voltage distribution system; fountain failure to use proper protection grade requirements of electrical equipment and cables. this desi
20、gn is completely contrary to the norms prescribed safety requirements, according to the drawings will remain a serious security risk. prior to august 1999, qingdao city, a fountain, several people took place, leisure death was shock casualties, it is because of design errors, underwater lighting, an
21、d submersible pumps due to power leakage which can not be timely. supervision in the pre-construction trial maps, and found the above problem, by the owners to design units in strict accordance with design specifications seek to amend the design. the correct approach is: outdoor courtyards and fount
22、ains should be used locally tt power distribution system, or tn-s system, and set the earth leakage protection (operating current should be no more than 30ma), which does not allow use of tn-c system; should be set well-grounded devices, fountains equipotential bonding should be done the design, but
23、 not solely from the building leads to a pe trunk grounding; submersible pumps and underwater lighting should be used diving cable distribution; 0 area electrical equipment should be used 1px8 protection level, a district should be 1px5 so. another example is low-voltage distribution lines, civil se
24、ction of choice. because the vast majority of civil electricity load for the single-phase loads, three-phase load imbalance will inevitably lead to the center line through unbalanced current; as computer equipment and various home appliances the development and popularization of low-voltage power gr
25、id high-order harmonic pollution, increasing , 3 times and the odd multiples of harmonics constitute a neutral current. midline over-current and thus lead to the phenomenon of electrical fires are also increasing. to this end, the provisions of the relevant design specification has been three-phase
26、four-wire or two-phase three-wire power distribution lines, when the electricity load the majority of single-phase load, the n line or pen-line cross-section should not be less than the phase-line cross-section; to gas discharge lamp as the main load circuit, n-line cross-section should not be less
27、than the phase cross-section . . , we can see that civil power distribution system of the trunk, branch lines and extensions of the wire cross-section principle, should be selected for n or pen-line cross-section and phase section of the same line. however, pre-trial supervision plans found that the
28、re are still a large number of civil power distribution design is still in use 80 years ago, the practice has been introduced, choice of n or pen-line cross-section is still phase 1 / 2 or even 1 / 4 to 1 / 3. this is the most common electrical design safety problems. again, with regard to the choic
29、e of variable distribution of the location of the relevant design specifications have clearly suggested that we should consider lifting and transport equipment, convenience, which is to ensure the availability and maintenance of basic requirements. we are responsible for supervision in recent years,
30、 many high-rise building project, which is set in the basement of the change with! electric diesel generator room configuration of reach of more than a violation of this requirement. example of a variable distribution reach of high-rise commercial and residential underground generator room, its tran
31、sport pathway was completely blocked chillers and groundwater box. construction and installation of the order can only be a first change, distribution equipment and installation in place after the installation of generating units and water chillers, but simply did not consider running after the fat
32、substation equipment maintenance, replacement and transport issues; another example of a high-rise office complex variable distribution of the ground floor room with hair, set on the first floor conference room of a bottom basement neither to consider the necessary transportation maintenance access,
33、 nor does it provide adequate width of the device can be brought into the doorframe. when the commissioner of the trial plan to discover and raise this issue, the design units in the answer turned out to be: the original design intent from a layer of the chamber office will change distribution and p
34、ower generation equipment in place before pouring lifting the floor of the hall. that intention was obviously wrong, even without considering civil construction may have on the place of the damage caused by electrical equipment, building operational after the repair and replacement of electrical equ
35、ipment and transportation is only forced open the floor conference room floor to solve it! notice of reinforced concrete frame structure building a reasonable service life of up to 50 years, while the transformation and distribution equipment life of only 20 years or less, regular or failure of the
36、maintenance cycle is even more short. therefore, electrical design must be properly considered its transportation and maintenance of lifting the problem of access. 2.2 design of shallow depth of the current construction design than the ministry of construction construction and engineering design doc
37、umentation, the depth of the provisions requirements are quite common, mainly in terms of design documents can be implemented deficiencies will lead directly to construction and installation problems or errorsmay also lead to lack of availability. required depth because they do not carry out the nec
38、essary calculation and labeling, but also often result in the design principles of the document itself appears rather difficult to discover the error will affect the project completion of use. for example, according to the depth of that power and lighting system diagram and the corresponding equipme
39、nt and materials should be detailed in the table indicate choice of electrical equipment and materials model, name, size and quantity parameters. since the reform and opening, chinas colorful electrical products market at home and abroad dazzling array of products for various models specification, t
40、he state can not be all types of electrical equipment and materials to establish a unified model. designed to identify a variety of equipment and materials parameters of the model specification appears to be particularly important, it is the owners or construction equipment units orders and procurem
41、ent basis. in recent years, electrical design documents, however, generally used only in the system diagram of the device symbol next to the annotation of the models or the device manufacturer product number, so that equipment orders at a loss, and often lead to errors. such as electrical lighting d
42、esign of a project, the designer in the system diagram of the circuit breaker marked only the symbol next to the a063m 20a, devices in the table is no exception, but have not specified the name and details of parameters, the construction unit interpreted as a regular 20a circuit breaker, because to
43、find less than the number of products under a separate procurement of another circuit breaker. the equipment and materials after the inspection by the supervisors check when the original a063m naishi haigs a kind of electromagnetic leakage circuit breaker product number, rated current 20a, rated res
44、idual operating current of 30ma. shows that the original design of these loop-based leakage should be protected. unclear but the design mark caused by ordering errors. had to re-purchase the replacement. anotherexample is the construction of many electrical diagram of the cable trench marked only th
45、e size and direction of the cable bracket and the cover does not make any provision, or only marked refer to page xx atlas xx, in fact plotting the country focused on either the size cable trench, its cable bracket and cover practices have provided a number of options for the design selection, desig
46、n is not selected then the construction side difficult choices, often according to the lowest construction program. often does not meet the actual needs, and even may lead to settlement of disputes. another example is provided by electric lighting map and places in the main room illumination standar
47、d values should be marked, of course, also require designers to carry out the calculation in accordance with calculation of illumination of lighting configurations. however, the current civil electric lighting design can be marked for illumination illumination standard values and calculations are ex
48、tremely rare, the vast majority of bay and functions of the rule of thumb according to the housing cloth lamp. most of the illumination of a departure from the standard stipulated by the state, affecting the use of functions. for example through the supervision of the trial map electrical constructi
49、on drawings in a school, after accounting for the design of illumination to achieve the value of laboratory and the classroom is only 50 701x, less than the national standard (150lx) of the half; a council office building in the offices and meeting rooms designed to illumination to only 70 80lx, com
50、puter room to only about 100h or so. nor was it even illumination standard value stipulated by the state (respectively, 150h and 200k) half. 2.3 the relevant professional interface design documents is unclear, do not follow the provisions of coordination is epidemic could easily lead to the construc
51、tion error for example, the widespread use of structural steel at present, as mine jieshan qi, yin xiaxian and grounding and equipotential bonding devices, electrical works required to be connected plotted points, embedded parts, indicating laying means and technical measures (such as welding requir
52、ements, etc.); and civil construction plans have embedded pieces detailing the relevant and related annotations and explanations. in fact the majority of the construction plans are only in the electrical diagram pick mine maps, and marked with the note very briefly, civil construction plans in hand,
53、 often without any relevant instructions and annotations. this gives the engineering supervision and construction have brought great difficulties, if the construction unit is vulnerable to lack of experience job (order) with the result of improper construction mistakes. the most common is the ground
54、 connection point reinforced network fault, leakage flux, and cited as the ground outside the join points, or embedded pieces of leak detection point is located. in particular, structural transformation layer, because of column (wall) in the main reinforcement adjustment, mine yin xiaxian wrong then
55、 the wrong welding steel case more likely. another example is the professional pipeline, line colliding with each other and mutually contradictory problem has become a frequently-occurring disease of the construction plans, abound, abound. we are responsible for supervision of the several buildings in the basement (including an underground garage) construction design, the trial maps ar
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