电线电缆截面积与载流量计算口诀和选用技巧

电线电缆截面积与载流量计算口诀和选用技巧 一、一般铜导线载流量导线的安全载流量是根据所允许的线芯最高温度、冷却条件、敷设条件来确定的。一般铜导线的安全载流量为5~8A/mm2，铝导线的安全载流量为3~5A/mm2。 如:2.5 mm2 BVV铜导线安全载流量的推荐值2.5×8A/mm2=20A 4 mm2 BVV铜导线安全载流量的推荐值4×8A/mm2=32A 二、计算铜导线截面积利用铜导线的安全载流量的推荐值5~8A/mm2，计算出所选取铜导线截面积S的上下范围: S=< I /(5~8)>=0.125 I ~0.2 I(mm2); S-----铜导线截面积(mm2);I-----负载电流(A) 三、功率计算一般负载(也可以成为用电器，如点灯、冰箱等等)分为两种，一种式电阻性负载，一种是电感性负载。对于电阻性负载的计算公式:P=UI 对于日光灯负载的计算公式:P=UIcosф，其中日光灯负载的功率因数cosф=0.5。不同电感性负载功率因数不同，统一计算家庭用电器时可以将功率因数cosф取0.8。也就是说如果一个家庭所有用电器加上总功率为6000瓦，则最大电流是 I=P/Ucosф=6000/220*0.8=34(A) 但是，一般情况下，家里的电器不可能同时使用，所以加上一个公用系数，公用系数一般0.5。所以，上面的计算应该改写成 I=P*公用系数/Ucosф=6000*0.5/220*0.8=17(A) 也就是说，这个家庭总的电流值为17A。则总闸空气开关不能使用16A，应该用大于17A的。 估算口诀: 二点五下乘以九，往上减一顺号走。 三十五乘三点五，双双成组减点五。 条件有变加折算，高温九折铜升级。 穿管根数二三四，八七六折满载流。 feel free to listen to their voices and help the masses solve problems, we were officially opened on May 10 "12345" Mayor calls, formulated rules and regulations, equipped with a full-time staff, a 24-hour on-duty system, people to call to receive, reply, action, reminders, feedback and so on. By year end, handled the crowd calls 1076, 94.7% feedback rate. By Mayor calls active coordination to solve a large number of bears on the immediate interests of the people and issues of great lives, but also for leadership research and decision to collect a lot of good ideas and suggestions, by all sectors of the community alike. Second, start Municipal Government Affairs Hall built. On May 11, we built and launched the city-government lobby, were settled in 12 departments, strict implementation of first asking duty system, service system, system of gratuitous, "receiving, internal coordination, head of the window handle, limited time concluded" one-stop service. By the end of today to accept various types of 3,273, originally of up to 100%. Running Government Affairs Hall, the convenience of the masses, promoting open Government, improve the investment environment and solve their practical problems, and so did a lot of work, masses, serve the community for the Government to play a very good "window, link, model". Third, create a city government public affairs network. We rely on the Government Web site, was completed on May 24, the province's first public affairs network. Over 说明: 本节口诀对各种绝缘线(橡皮和塑料绝缘线)的载流量(安全电流)不是直接指出，而是“截面乘上一定的倍数”来 表 关于同志近三年现实表现材料材料类招标技术评分表图表与交易pdf视力表打印pdf用图表说话 pdf 示，通过心算而得。倍数随截面的增大而减小。 “二点五下乘以九，往上减一顺号走”说的是2(5mm’及以下的各种截面铝芯绝缘线，其载流量约为截面数的9倍。如2(5mm’导线，载流量为2(5×9,22(5(A)。从4mm’及以上导线的载流量和截面数的倍数关系是顺着线号往上排，倍数逐次减l，即4×8、6×7、10×6、16×5、25×4。 “三十五乘三点五，双双成组减点五”，说的是35mm”的导线载流量为截面数的3(5倍，即35×3(5,122(5(A)。从50mm’及以上的导线，其载流量与截面数之间的倍数关系变为两个两个线号成一组，倍数依次减0(5。即50、70mm’导线的载流量为截面数的3倍;95、120mm”导线载流量是其截面积数的2(5倍，依次类推。 条件有变加折算，高温九折铜升级”。上述口诀是铝芯绝缘线、明敷在环境温度25?的条件下而定的。若铝芯绝缘线明敷在环境温度长期高于25?的地区，导线载流量可按上述口诀计算 方法 快递客服问题件处理详细方法山木方法pdf计算方法pdf华与华方法下载八字理论方法下载 算出，然后再打九折即可;当使用的不是铝线而是铜芯绝缘线，它的载流量要比同规格铝线略大一些，可按上述口诀方法算出比铝线加大一个线号的载流量。如16mm’铜线的载流量，可按25mm2铝线计算 导体载流量的计算口诀 feel free to listen to their voices and help the masses solve problems, we were officially opened on May 10 "12345" Mayor calls, formulated rules and regulations, equipped with a full-time staff, a 24-hour on-duty system, people to call to receive, reply, action, reminders, feedback and so on. By year end, handled the crowd calls 1076, 94.7% feedback rate. By Mayor calls active coordination to solve a large number of bears on the immediate interests of the people and issues of great lives, but also for leadership research and decision to collect a lot of good ideas and suggestions, by all sectors of the community alike. Second, start Municipal Government Affairs Hall built. On May 11, we built and launched the city-government lobby, were settled in 12 departments, strict implementation of first asking duty system, service system, system of gratuitous, "receiving, internal coordination, head of the window handle, limited time concluded" one-stop service. By the end of today to accept various types of 3,273, originally of up to 100%. Running Government Affairs Hall, the convenience of the masses, promoting open Government, improve the investment environment and solve their practical problems, and so did a lot of work, masses, serve the community for the Government to play a very good "window, link, model". Third, create a city government public affairs network. We rely on the Government Web site, was completed on May 24, the province's first public affairs network. Over 1、用途:各种导线的载流量(安全电流)通常可以从手册中查找。但利用口诀再配合一些简单的心算,便可直接算出,不必查表。导线的载流量与导线的载面有关,也与导线的材料(铝或铜),型号(绝缘线或裸线等),敷设方法(明敷或穿管等)以及环境温度(25度左右或更大)等有关,影响的因素较多,计算也较复杂。 10 下五，1 0 0 上二。2 5 ，3 5 ，四三界。7 0 ，95 ，两倍半。穿管温度， 八九折。裸线加一半。铜线升级算。 4.说明:口诀是以铝芯绝缘线,明敷在环境温度25 度的条件为准。若条件不同, 口诀另有说明。绝缘线包括各种型号的橡皮绝缘线或塑料绝缘线。口诀对各种截面的载流量(电流,安)不是直接指出,而是“用截面乘上一定的倍数”,来表示。为此,应当先熟悉导线截面,(平方毫米)的排列: 1 1.5 2.5 4 6 10 16 25 35 50 7O 95 l20 150 185...... 生产厂制造铝芯绝缘线的截面积通常从而2.5开始,铜芯绝缘线则从1 开始;裸铝线从16 开始;裸铜线从10 开始。 ?这口诀指出:铝芯绝缘线载流量,安,可以按截面数的多少倍来计算。口诀中阿拉伯数码表示导线截面(平方毫米),汉字表示倍数。把口诀的截面与倍数关系排列起来便如下: ..10 16-25 35-50 70-95 120.... 五倍 四倍 三倍 两倍半 二倍 现在再和口诀对照就更清楚了.原来“10 下五”是指截面从10 以下,载流量都是feel free to listen to their voices and help the masses solve problems, we were officially opened on May 10 "12345" Mayor calls, formulated rules and regulations, equipped with a full-time staff, a 24-hour on-duty system, people to call to receive, reply, action, reminders, feedback and so on. By year end, handled the crowd calls 1076, 94.7% feedback rate. By Mayor calls active coordination to solve a large number of bears on the immediate interests of the people and issues of great lives, but also for leadership research and decision to collect a lot of good ideas and suggestions, by all sectors of the community alike. Second, start Municipal Government Affairs Hall built. On May 11, we built and launched the city-government lobby, were settled in 12 departments, strict implementation of first asking duty system, service system, system of gratuitous, "receiving, internal coordination, head of the window handle, limited time concluded" one-stop service. By the end of today to accept various types of 3,273, originally of up to 100%. Running Government Affairs Hall, the convenience of the masses, promoting open Government, improve the investment environment and solve their practical problems, and so did a lot of work, masses, serve the community for the Government to play a very good "window, link, model". Third, create a city government public affairs network. We rely on the Government Web site, was completed on May 24, the province's first public affairs network. Over 截面数的五倍。“100 上二”(读百上二),是指截面100以上,载流量都是截面数的二倍。截面25与35 是四倍和三倍的分界处.这就是“口诀25、35 四三界”。而截面70、95 则为2.5 倍。从上面的排列,可以看出:除10 以下及100 以上之外,中间的导线截面是每两种规格属同一倍数。 下面以明敷铝芯绝缘线,环境温度为25 度,举例说明: 【例1】 6 平方毫米的,按10 下五,算得载流量为30 安。 【例2】150 平方毫米的,按100 上二,算得载流量为300 安。 【例3】70 平方毫米的,按70、95 两2 倍半,算得载流量为175安。 从上面的排列还可以看出,倍数随截面的增大而减小。在倍数转变的交界处,误差稍大些。比如截面25 与35 是四倍与三倍的分界处,25属四倍的范围,但靠近向三倍变化的一侧,它按口诀是四倍,即100 安。但实际不到四倍(按手册为97 安)。而35 则相反,按口诀是三倍,即105 安,实际是117 安。不过这对使用的影响并不大。当然,若能胸中有数,在选择导线截面时,25 的不让它满到100 安,35 的则可以略为超过105 安便更准确了。同样,2.5平方毫米的导线位置在五倍的最始(左)端,实际便不止五倍〈最大可达20安以上〉,不过为了减少导线内的电能损耗,通常都不用到这么大,手册中一般也只标12 安。 ? 从这以下,口诀便是对条件改变的处理。本句:穿管温度八九折,是指若是穿管敷设(包括槽板等敷设,即导线加有保护套层,不明露的)按?计算后,再打八折(乘0.8)若环境温度超过25 度,应按?计算后,再打九折。(乘0.9)。 关于环境温度,按规定是指夏天最热月的平均最高温度。实际上,温度是变动的,一般情况下,它影响导体载流并不很大。因此,只对某些高温车间或较热地区超过25 度较多时,才考虑打折扣。 还有一种情况是两种条件都改变(穿管又温度较高)。则按?计算后打八折,再打九feel free to listen to their voices and help the masses solve problems, we were officially opened on May 10 "12345" Mayor calls, formulated rules and regulations, equipped with a full-time staff, a 24-hour on-duty system, people to call to receive, reply, action, reminders, feedback and so on. By year end, handled the crowd calls 1076, 94.7% feedback rate. By Mayor calls active coordination to solve a large number of bears on the immediate interests of the people and issues of great lives, but also for leadership research and decision to collect a lot of good ideas and suggestions, by all sectors of the community alike. Second, start Municipal Government Affairs Hall built. On May 11, we built and launched the city-government lobby, were settled in 12 departments, strict implementation of first asking duty system, service system, system of gratuitous, "receiving, internal coordination, head of the window handle, limited time concluded" one-stop service. By the end of today to accept various types of 3,273, originally of up to 100%. Running Government Affairs Hall, the convenience of the masses, promoting open Government, improve the investment environment and solve their practical problems, and so did a lot of work, masses, serve the community for the Government to play a very good "window, link, model". Third, create a city government public affairs network. We rely on the Government Web site, was completed on May 24, the province's first public affairs network. Over 折。或者简单地一次打七折计算(即0.8 × 0.9=0.72,约0.7)。这也可以说是穿管温度,八九折的意思。 例如:(铝芯绝缘线)10 平方毫米的,穿管(八折)40 安(10 × 5× 0.8 , 40) 穿管又高温(七折)35 安(1O × 5 × 0.7=35) 95平方毫米的,穿管(八折)190安(95×2.5×0.8,190) 高温(九折),214 安(95 × 2.5 × 0.9=213.8) 穿管又高温(七折)。166 安(95 × 2.5 × 0.7 , 166.3) ?对于裸铝线的载流量,口诀指出,裸线加一半,即按?中计算后再加一半(乘l.5)。这是指同样截面的铝芯绝缘线与铝裸线比较,载流量可加大一半。 【例1】 16 平方毫米的裸铝线,96 安(16 × 4 × 1.5 , 96) 。高温,86 安(16 × 4 × 1.5 × 0.9=86.4) 【例2】 35 平方毫米裸铝线,150 安(35 × 3 × 1.5=157.5) 【例3】120 平方毫米裸铝线，360 安(120 × 2 × 1.5 , 360) ?对于铜导线的载流量，口诀指出,铜线升级算。即将铜导线的截面按截面排列顺序提升一级,再按相应的铝线条件计算。 【例一】 35 平方的裸铜线25 度,升级为50 平方毫米,再按50 平方毫米裸铝线,25 度计算为225 安(50 × 3 × 1.5) 【例二】 16 平方毫米铜绝缘线25 度,按25 平方毫米铝绝缘的相同条件,计算为100 安(25 × 4) 【例三】 95 平方毫米铜绝缘线25 度,穿管,按120 平方毫米铝绝缘线的相同条件,计算为192 安(120 × 2 × 0.8)。 feel free to listen to their voices and help the masses solve problems, we were officially opened on May 10 "12345" Mayor calls, formulated rules and regulations, equipped with a full-time staff, a 24-hour on-duty system, people to call to receive, reply, action, reminders, feedback and so on. By year end, handled the crowd calls 1076, 94.7% feedback rate. By Mayor calls active coordination to solve a large number of bears on the immediate interests of the people and issues of great lives, but also for leadership research and decision to collect a lot of good ideas and suggestions, by all sectors of the community alike. Second, start Municipal Government Affairs Hall built. On May 11, we built and launched the city-government lobby, were settled in 12 departments, strict implementation of first asking duty system, service system, system of gratuitous, "receiving, internal coordination, head of the window handle, limited time concluded" one-stop service. By the end of today to accept various types of 3,273, originally of up to 100%. Running Government Affairs Hall, the convenience of the masses, promoting open Government, improve the investment environment and solve their practical problems, and so did a lot of work, masses, serve the community for the Government to play a very good "window, link, model". Third, create a city government public affairs network. We rely on the Government Web site, was completed on May 24, the province's first public affairs network. Over 电缆截面估算方法 先估算负荷电流 1(用途 这是根据用电设备的功率(千瓦或千伏安)算出电流(安)的口诀。 电流的大小直接与功率有关，也与电压、相别、力率(又称功率因数)等有关。一般有公式可供计算。由于工厂常用的都是380/220伏三相四线系统，因此，可以根据功率的大小直接算出电流。 2.口诀 低压380/220伏系统每千瓦的电流，安。 千瓦、电流，如何计算, 电力加倍，电热加半。 ? 单相千瓦，4.5安。 ? 单相380，电流两安半。 ? 3( 说明 口诀是以380/220伏三相四线系统中的三相设备为准，计算每千瓦的安数。对于某些单相或电压不同的单相设备，其每千瓦的安数，口诀另外作了说明。 ? 这两句口诀中，电力专指电动机。在380伏三相时(力率0.8左右),电动机每千瓦的电流约为2安.即将”千瓦数加一倍”(乘2)就是电流，安。这电流也称电动机的额定电流。 【例1】 5.5千瓦电动机按“电力加倍”算得电流为11安。 【例2】 40千瓦水泵电动机按“电力加倍”算得电流为80安。 feel free to listen to their voices and help the masses solve problems, we were officially opened on May 10 "12345" Mayor calls, formulated rules and regulations, equipped with a full-time staff, a 24-hour on-duty system, people to call to receive, reply, action, reminders, feedback and so on. By year end, handled the crowd calls 1076, 94.7% feedback rate. By Mayor calls active coordination to solve a large number of bears on the immediate interests of the people and issues of great lives, but also for leadership research and decision to collect a lot of good ideas and suggestions, by all sectors of the community alike. Second, start Municipal Government Affairs Hall built. On May 11, we built and launched the city-government lobby, were settled in 12 departments, strict implementation of first asking duty system, service system, system of gratuitous, "receiving, internal coordination, head of the window handle, limited time concluded" one-stop service. By the end of today to accept various types of 3,273, originally of up to 100%. Running Government Affairs Hall, the convenience of the masses, promoting open Government, improve the investment environment and solve their practical problems, and so did a lot of work, masses, serve the community for the Government to play a very good "window, link, model". Third, create a city government public affairs network. We rely on the Government Web site, was completed on May 24, the province's first public affairs network. Over 电热是指用电阻加热的电阻炉等。三相380伏的电热设备，每千瓦的电流为1.5安。即将“千瓦数加一半”(乘1.5)就是电流，安。 【例1】 3千瓦电加热器按“电热加半”算得电流为4.5安。 【例2】 15千瓦电阻炉按“电热加半”算得电流为23安。 这句口诀不专指电热，对于照明也适用。虽然照明的灯泡是单相而不是三相，但对照明供电的三相四线干线仍属三相。只要三相大体平衡也可这样计算。此外，以千伏安为单位的电器(如变压器或整流器)和以千乏为单位的移相电容器(提高力率用)也都适用。即时说，这后半句虽然说的是电热，但包括所有以千伏安、千乏为单位的用电设备，以及以千瓦为单位的电热和照明设备。 【例1】 12千瓦的三相(平衡时)照明干线按“电热加半”算得电流为18安。 【例2】 30千伏安的整流器按“电热加半”算得电流为45安(指380伏三相交流侧)。 【例3】 320千伏安的配电变压器按“电热加半”算得电流为480安(指380/220伏低压侧)。 【例4】 100千乏的移相电容器(380伏三相)按“电热加半”算得电流为150安。 ?在380/220伏三相四线系统中，单相设备的两条线，一条接相线而另一条接零线的(如照明设备)为单相220伏用电设备。这种设备的力率大多为1，因此，口诀便直接说明“单相(每)千瓦4.5安”。计算时，只要“将千瓦数乘4.5”就是电流，安。 feel free to listen to their voices and help the masses solve problems, we were officially opened on May 10 "12345" Mayor calls, formulated rules and regulations, equipped with a full-time staff, a 24-hour on-duty system, people to call to receive, reply, action, reminders, feedback and so on. By year end, handled the crowd calls 1076, 94.7% feedback rate. By Mayor calls active coordination to solve a large number of bears on the immediate interests of the people and issues of great lives, but also for leadership research and decision to collect a lot of good ideas and suggestions, by all sectors of the community alike. Second, start Municipal Government Affairs Hall built. On May 11, we built and launched the city-government lobby, were settled in 12 departments, strict implementation of first asking duty system, service system, system of gratuitous, "receiving, internal coordination, head of the window handle, limited time concluded" one-stop service. By the end of today to accept various types of 3,273, originally of up to 100%. Running Government Affairs Hall, the convenience of the masses, promoting open Government, improve the investment environment and solve their practical problems, and so did a lot of work, masses, serve the community for the Government to play a very good "window, link, model". Third, create a city government public affairs network. We rely on the Government Web site, was completed on May 24, the province's first public affairs network. Over 同上面一样，它适用于所有以千伏安为单位的单相220伏用电设备，以及以千瓦为单位的电热及照明设备，而且也适用于220伏的直流。 【例1】 500伏安(0.5千伏安)的行灯变压器(220伏电源侧)按“单相千瓦、4.5 安”算得电流为2.3安。 【例2】 1000瓦投光灯按“单相千瓦、4.5安”算得电流为4.5安。 对于电压更低的单相，口诀中没有提到。可以取220伏为标准，看电压降低多少，电流就反过来增大多少。比如36伏电压，以220伏为标准来说，它降低到1/6，电流就应增大到6倍，即每千瓦的电流为6*4.5=27安。比如36伏、60瓦的行灯每只电流为0.06*27=1.6安，5只便共有8安。 ?在380/220伏三相四线系统中，单相设备的两条线都是接到相线上的，习惯上称为单相380伏用电设备(实际是接在两相上)。这种设备当以千瓦为单位时，力率大多为1，口诀也直接说明:“单相380，电流两安半”。它也包括以千伏安为单位的380伏单相设备。计算时，只要“将千瓦或千伏安数乘2.5”就是电流，安。 【例1】 32千瓦钼丝电阻炉接单相380伏，按“电流两安半”算得电流为80安。 【例2】 2千伏安的行灯变压器，初级接单相380伏，按“电流两安半”算得电流为5安。 【例3】 21千伏安的交流电焊变压器，初级接单相380伏，按“电流两安半”算得电流为53安。 feel free to listen to their voices and help the masses solve problems, we were officially opened on May 10 "12345" Mayor calls, formulated rules and regulations, equipped with a full-time staff, a 24-hour on-duty system, people to call to receive, reply, action, reminders, feedback and so on. By year end, handled the crowd calls 1076, 94.7% feedback rate. By Mayor calls active coordination to solve a large number of bears on the immediate interests of the people and issues of great lives, but also for leadership research and decision to collect a lot of good ideas and suggestions, by all sectors of the community alike. Second, start Municipal Government Affairs Hall built. On May 11, we built and launched the city-government lobby, were settled in 12 departments, strict implementation of first asking duty system, service system, system of gratuitous, "receiving, internal coordination, head of the window handle, limited time concluded" one-stop service. By the end of today to accept various types of 3,273, originally of up to 100%. Running Government Affairs Hall, the convenience of the masses, promoting open Government, improve the investment environment and solve their practical problems, and so did a lot of work, masses, serve the community for the Government to play a very good "window, link, model". Third, create a city government public affairs network. We rely on the Government Web site, was completed on May 24, the province's first public affairs network. Over 估算出负荷的电流后在根据电流选出相应导线的截面,选导线截面时有几个方面要考虑到 一是导线的机械强度 二是导线的电流密度(安全截流量), 三是允许电压降 电压降的估算 1(用途 根据线路上的负荷矩，估算供电线路上的电压损失，检查线路的供电质量。 2(口诀 提出一个估算电压损失的基准数据，通过一些简单的计算，可估出供电线路上的电压损失。 压损根据“千瓦(米”，2.5铝线20—1。截面增大荷矩大，电压降低平方低。 ? 三相四线6倍计，铜线乘上1.7。 ? 感抗负荷压损高，10下截面影响小，若以力率0.8计，10上增加0.2至1。 ? 3(说明 电压损失计算与较多的因素有关,计算较复杂。 估算时，线路已经根据负荷情况选定了导线及截面，即有关条件已基本具备。 电压损失是按“对额定电压损失百分之几”来衡量的。口诀主要列出估算电压损失的最基本的数据，多少“负荷矩”电压损失将为1%。当负荷矩较大时，电压损失也就相应增大。因些，首先应算出这线路的负荷矩。 feel free to listen to their voices and help the masses solve problems, we were officially opened on May 10 "12345" Mayor calls, formulated rules and regulations, equipped with a full-time staff, a 24-hour on-duty system, people to call to receive, reply, action, reminders, feedback and so on. By year end, handled the crowd calls 1076, 94.7% feedback rate. By Mayor calls active coordination to solve a large number of bears on the immediate interests of the people and issues of great lives, but also for leadership research and decision to collect a lot of good ideas and suggestions, by all sectors of the community alike. Second, start Municipal Government Affairs Hall built. On May 11, we built and launched the city-government lobby, were settled in 12 departments, strict implementation of first asking duty system, service system, system of gratuitous, "receiving, internal coordination, head of the window handle, limited time concluded" one-stop service. By the end of today to accept various types of 3,273, originally of up to 100%. Running Government Affairs Hall, the convenience of the masses, promoting open Government, improve the investment environment and solve their practical problems, and so did a lot of work, masses, serve the community for the Government to play a very good "window, link, model". Third, create a city government public affairs network. We rely on the Government Web site, was completed on May 24, the province's first public affairs network. Over 所谓负荷矩就是负荷(千瓦)乘上线路长度(线路长度是指导线敷设长度“米”，即导线走过的路径，不论线路的导线根数。)，单位就是“千瓦(米”。对于放射式线路，负荷矩的计算很简单。如下图1，负荷矩便是20*30=600千瓦(米。但如图2的树干式线路，便麻烦些。对于其中5千瓦 设备安装位置的负荷矩应这样算:从线路供电点开始，根据线路分支的情况把它分成三段。在线路的每一段，三个负荷(10、8、5千瓦)都通过，因此负荷矩为: 第一段:10*(10+8+5)=230千瓦(米 第二段:5*(8+5)=65千瓦(米 第三段:10*5=50千瓦(米 至5千瓦设备处的总负荷矩为:230+65+50=345千瓦(米 下面对口诀进行说明: ?首先说明计算电压损失的最基本的根据是负荷矩:千瓦(米 接着提出一个基准数据: 2 .5平方毫米的铝线，单相220伏，负荷为电阻性(力率为1)，每20“千瓦(米”负荷矩电压损失为1%。这就是口诀中的“2 .5铝线20—1”。 在电压损失1%的基准下，截面大的，负荷矩也可大些，按正比关系变化。比如10平方毫米的铝线，截面为2 .5平方毫米的4倍，则20*4=80千瓦(米，即这种导线负荷矩为80千瓦(米，电压损失才1%。其余截面照些类推。 当电压不是220伏而是其它数值时，例如36伏，则先找出36伏相当于220伏的1/6。此时，这种线路电压损失为1%的负荷矩不是20千瓦(米，而应按1/6的平方即1/36来降低，这就是20*(1/36)=0 .55千瓦(米。即是说，36伏时，每0 .55千瓦(米(即每550瓦(米)，电压损失降低1%。 feel free to listen to their voices and help the masses solve problems, we were officially opened on May 10 "12345" Mayor calls, formulated rules and regulations, equipped with a full-time staff, a 24-hour on-duty system, people to call to receive, reply, action, reminders, feedback and so on. By year end, handled the crowd calls 1076, 94.7% feedback rate. By Mayor calls active coordination to solve a large number of bears on the immediate interests of the people and issues of great lives, but also for leadership research and decision to collect a lot of good ideas and suggestions, by all sectors of the community alike. Second, start Municipal Government Affairs Hall built. On May 11, we built and launched the city-government lobby, were settled in 12 departments, strict implementation of first asking duty system, service system, system of gratuitous, "receiving, internal coordination, head of the window handle, limited time concluded" one-stop service. By the end of today to accept various types of 3,273, originally of up to 100%. Running Government Affairs Hall, the convenience of the masses, promoting open Government, improve the investment environment and solve their practical problems, and so did a lot of work, masses, serve the community for the Government to play a very good "window, link, model". Third, create a city government public affairs network. We rely on the Government Web site, was completed on May 24, the province's first public affairs network. Over “电压降低平方低”不单适用于额定电压更低的情况，也可适用于额定电压更高的情况。这时却要按平方升高了。例如单相380伏，由于电压380伏为220伏的1 .7倍，因此电压损失1%的负荷矩应为20*1 .7的平方=58千瓦(米。 从以上可以看出:口诀“截面增大荷矩大，电压降低平方低”。都是对照基准数据“2 .5铝线20—1”而言的。 【例1】 一条220伏照明支路，用2 .5平方毫米铝线，负荷矩为76千瓦(米。由于76是20的3 .8倍(76/20=3 .8)，因此电压损失为3 .8%。 【例2】 一条4平方毫米铝线敷设的40米长的线路，供给220伏1千瓦的单相电炉2只，估算电压损失是: 先算负荷矩2*40=80千瓦(米。再算4平方毫米铝线电压损失1%的负荷矩，根据“截面增大负荷矩大”的原则，4和2 .5比较，截面增大为1 .6倍(4/2 .5=1 .6)，因此负荷矩增为 20*1 .6=32千瓦(米(这是电压损失1%的数据)。最后计算80/32=2 .5，即这条线路电压损失为2 .5%。 ?当线路不是单相而是三相四线时，(这三相四线一般要求三相负荷是较平衡的。它的电压是和单相相对应的。如果单相为220伏，对应的三相便是380伏，即380/220伏。)同样是2 .5平方毫米的铝线，电压损失1%的负荷矩是?中基准数据的6倍，即20*6=120千瓦(米。至于截面或电压变化，这负荷矩的数值，也要相应变化。 当导线不是铝线而是铜线时，则应将铝线的负荷矩数据乘上1 .7，如“2 .5铝线20—1”改为同截面的铜线时，负荷矩则改为20*1 .7=34千瓦(米，电压损失才1%。 【例3】 前面举例的照明支路，若是铜线，则76/34=2 .2，即电压损失为2 .2%。feel free to listen to their voices and help the masses solve problems, we were officially opened on May 10 "12345" Mayor calls, formulated rules and regulations, equipped with a full-time staff, a 24-hour on-duty system, people to call to receive, reply, action, reminders, feedback and so on. By year end, handled the crowd calls 1076, 94.7% feedback rate. By Mayor calls active coordination to solve a large number of bears on the immediate interests of the people and issues of great lives, but also for leadership research and decision to collect a lot of good ideas and suggestions, by all sectors of the community alike. Second, start Municipal Government Affairs Hall built. On May 11, we built and launched the city-government lobby, were settled in 12 departments, strict implementation of first asking duty system, service system, system of gratuitous, "receiving, internal coordination, head of the window handle, limited time concluded" one-stop service. By the end of today to accept various types of 3,273, originally of up to 100%. Running Government Affairs Hall, the convenience of the masses, promoting open Government, improve the investment environment and solve their practical problems, and so did a lot of work, masses, serve the community for the Government to play a very good "window, link, model". Third, create a city government public affairs network. We rely on the Government Web site, was completed on May 24, the province's first public affairs network. Over 对电炉供电的那条线路，若是铜线，则80/(32*1 .7)=1 .5，电压损失为1 .5%。 【例4】 一条50平方毫米铝线敷设的380伏三相线路，长30米，供给一台60千瓦的三相电炉。电压损失估算是: 先算负荷矩:60*30=1800千瓦(米。 再算50平方毫米铝线在380伏三相的情况下电压损失1%的负荷矩:根据“截面增大荷矩大”，由于50是2 .5的20倍，因此应乘20，再根据“三相四线6倍计”，又要乘6，因此，负荷矩增大为20*20*6=2400千瓦(米。 最后1800/2400=0 .75，即电压损失为0 .75%。 ?以上都是针对电阻性负荷而言。对于感抗性负荷(如电动机)，计算方法比上面的更复杂。但口诀首先指出:同样的负荷矩——千瓦(米，感抗性负荷电压损失比电阻性的要高一些。它与截面大小及导线敷设之间的距离有关。对于10平方毫米及以下的导线则影响较小，可以不增高。 对于截面10平方毫米以上的线路可以这样估算:先按?或?算出电压损失，再“增加0 .2至1”，这是指增加0 .2至1倍，即再乘1 .2至2。这可根据截面大小来定，截面大的乘大些。例如70平方毫米的可乘1 .6，150平方毫米可乘2。 以上是指线路架空或支架明敷的情况。对于电缆或穿管线路，由于线路距离很小面影响不大，可仍按?、?的规定估算，不必增大或仅对大截面的导线略为增大(在0 .2以内)。 【例5】 图1中若20千瓦是380伏三相电动机，线路为3*16铝线支架明敷，则电压损失估算为:已知负荷矩为600千瓦(米。 计算截面16平方毫米铝线380伏三相时，电压损失1%的负荷矩:由于16是2 .5的6 .4倍，三相负荷矩又是单相的6倍，因此负荷矩增为:20*6 .4*6=768千瓦(米 600/768=0 .8 feel free to listen to their voices and help the masses solve problems, we were officially opened on May 10 "12345" Mayor calls, formulated rules and regulations, equipped with a full-time staff, a 24-hour on-duty system, people to call to receive, reply, action, reminders, feedback and so on. By year end, handled the crowd calls 1076, 94.7% feedback rate. By Mayor calls active coordination to solve a large number of bears on the immediate interests of the people and issues of great lives, but also for leadership research and decision to collect a lot of good ideas and suggestions, by all sectors of the community alike. Second, start Municipal Government Affairs Hall built. On May 11, we built and launched the city-government lobby, were settled in 12 departments, strict implementation of first asking duty system, service system, system of gratuitous, "receiving, internal coordination, head of the window handle, limited time concluded" one-stop service. By the end of today to accept various types of 3,273, originally of up to 100%. Running Government Affairs Hall, the convenience of the masses, promoting open Government, improve the investment environment and solve their practical problems, and so did a lot of work, masses, serve the community for the Government to play a very good "window, link, model". Third, create a city government public affairs network. We rely on the Government Web site, was completed on May 24, the province's first public affairs network. Over 即估算的电压损失为0 .8%。但现在是电动机负荷，而且导线截面在10以上，因此应增加一些。根据截面情况，考虑1 .2，估算为0 .8*1 .2=0 .96，可以认为电压损失约1%。 以上就是电压损失的估算方法。最后再就有关这方面的问题谈几点: 一、线路上电压损失大到多少质量就不好,一般以7~8%为原则。(较严格的说法是:电压损失以用电设备的额定电压为准(如380/220伏)，允许低于这额定电压的5%(照明为2 .5%)。但是配电变压器低压母线端的电压规定又比额定电压高5%(400/230伏)，因此从变压器开始至用电设备的整个线路中，理论上共可损失5%+5%=10%，但通常却只允许7~8%。这是因为还要扣除变压器内部的电压损失以及变压器力率低的影响的缘故。)不过这7~8%是指从配电变压器低压侧开始至计算的那个用电设备为止的全部线路。它通常包括有户外架空线、户内干线、支线等线段。应当是各段结果相加，全部约7~8%。 二、估算电压损失是设计的工作，主要是防止将来使用时出现电压质量不佳的现象。由于影响计算的因素较多(主要的如计算干线负荷的准确性，变压器电源侧电压的稳定性等)，因此，对计算要求很精确意义不大，只要大体上胸中有数就可以了。比如截面相比的关系也可简化为4比2 .5为1 .5倍，6比2 .5为2 .5倍，16比2 .5倍为6倍。这样计算会更方便些。 三、在估算电动机线路电压损失中，还有一种情况是估算电动机起动时的电压损失。这是若损失太大，电动机便不能直接起动。由于起动时的电流大，力率低，一般规定起动时的电压损失可达15%。这种起动时的电压损失计算更为复杂，但可用上述口诀介绍的计算结果判断，一般截面25平方毫米以内的铝线若符合5%的要求，也可符合直接起动的要求:35、50平方毫米的铝线若电压损失在3 .5%以内，也可满足;70、95平方毫米的铝线若电压损失在2 .5%以内，也可满足;feel free to listen to their voices and help the masses solve problems, we were officially opened on May 10 "12345" Mayor calls, formulated rules and regulations, equipped with a full-time staff, a 24-hour on-duty system, people to call to receive, reply, action, reminders, feedback and so on. By year end, handled the crowd calls 1076, 94.7% feedback rate. By Mayor calls active coordination to solve a large number of bears on the immediate interests of the people and issues of great lives, but also for leadership research and decision to collect a lot of good ideas and suggestions, by all sectors of the community alike. Second, start Municipal Government Affairs Hall built. On May 11, we built and launched the city-government lobby, were settled in 12 departments, strict implementation of first asking duty system, service system, system of gratuitous, "receiving, internal coordination, head of the window handle, limited time concluded" one-stop service. By the end of today to accept various types of 3,273, originally of up to 100%. Running Government Affairs Hall, the convenience of the masses, promoting open Government, improve the investment environment and solve their practical problems, and so did a lot of work, masses, serve the community for the Government to play a very good "window, link, model". Third, create a city government public affairs network. We rely on the Government Web site, was completed on May 24, the province's first public affairs network. Over 而120平方毫米的铝线若电压损失在1 .5以内。才可满足。这3 .5%，2 .5%，1 .5 .%刚好是5%的七、五、三折，因此可以简单记为:“35以上，七、五、三折”。 四、假如在使用中确实发现电压损失太大，影响用电质量，可以减少负荷(将一部分负荷转移到别的较轻的线路，或另外增加一回路)，或者将部分线段的截面增大(最好增大前面的干线)来解决。对于电动机线路，也可以改用电缆来减少电压损失。当电动机无法直接启动时，除了上述解决办法外，还可以采用降压起动设备(如星-三角起动器或自耦减压起动器等)来解决 根据电流来选截面 1(用途 各种导线的截流量(安全用电)通常可以从手册中查找。但利用口诀再配合一些简单的心算，便可直接算出，不必查表。 导线的截流量与导线的截面有关，也与导线的材料(铝或铜)、型号(绝缘线或裸线等)、敷设方法(明敷或穿管等)以及环境温度(25?左右或更大)等有关，影响的因素较多，计算也较复杂。 2(口诀 铝心绝缘线截流量与截面的倍数关系: S(截面)=0.785*D(直径)的平方 10下5，100上二，25、35，四三界，70、95，两倍半。 ? 穿管、温度，八九折。 ? 裸线加一半。 ? 铜线升级算。 ? feel free to listen to their voices and help the masses solve problems, we were officially opened on May 10 "12345" Mayor calls, formulated rules and regulations, equipped with a full-time staff, a 24-hour on-duty system, people to call to receive, reply, action, reminders, feedback and so on. By year end, handled the crowd calls 1076, 94.7% feedback rate. By Mayor calls active coordination to solve a large number of bears on the immediate interests of the people and issues of great lives, but also for leadership research and decision to collect a lot of good ideas and suggestions, by all sectors of the community alike. Second, start Municipal Government Affairs Hall built. On May 11, we built and launched the city-government lobby, were settled in 12 departments, strict implementation of first asking duty system, service system, system of gratuitous, "receiving, internal coordination, head of the window handle, limited time concluded" one-stop service. By the end of today to accept various types of 3,273, originally of up to 100%. Running Government Affairs Hall, the convenience of the masses, promoting open Government, improve the investment environment and solve their practical problems, and so did a lot of work, masses, serve the community for the Government to play a very good "window, link, model". Third, create a city government public affairs network. We rely on the Government Web site, was completed on May 24, the province's first public affairs network. Over 3(说明 口诀是以铝芯绝缘线、明敷在环境温度25?的条件为准。若条件不同，口诀另有说明。 绝缘线包括各种型号的橡皮绝缘线或塑料绝缘线。 口诀对各种截面的截流量(电流，安)不是直接指出，而是用“截面乘上一定倍数”来表示。为此，应当先熟悉导线截面(平方毫米)的排列: 1 1.5 2.5 4 6 10 16 25 35 50 70 95 120 150 185 ((((((( 生产厂制造铝芯绝缘线的截面通常从2.5开始,铜芯绝缘线则从1开始;裸铝线从16开始，裸铜线则从10开始。 ?这口诀指出:铝芯绝缘线截流量，安，可以按“截面数的多少倍”来计算。口诀中阿拉伯数字表示导线截面(平方毫米)，汉字数字表示倍数。把口诀的“截面与倍数关系”排列起来便如下: (((10*5 16、25*4 35 、45*3 70 、95*2.5 120*2(((((( 现在再和口诀对照就更清楚了，原来“10下五”是指截面从10以下，截流量都是截面数的五倍。“100上二”是指截面100以上，截流量都是截面数的二倍。截面25与35是四倍和三倍的分界处。这就是口诀“25、35四三界”。而截面70、95则为二点五倍。从上面的排列可以看出:除10以下及100以上之处，中间的导线截面是每每两种规格属同一种倍数。 下面以明敷铝芯绝缘线，环境温度为25?，举例说明: 【例1】6平方毫米的，按“10下五”算得截流量为30安。 【例2】150平方毫米的，按“100上二”算得截流量为300安。 【例3】70平方毫米的，按“70、95两倍半”算得截流量为175安。 feel free to listen to their voices and help the masses solve problems, we were officially opened on May 10 "12345" Mayor calls, formulated rules and regulations, equipped with a full-time staff, a 24-hour on-duty system, people to call to receive, reply, action, reminders, feedback and so on. By year end, handled the crowd calls 1076, 94.7% feedback rate. By Mayor calls active coordination to solve a large number of bears on the immediate interests of the people and issues of great lives, but also for leadership research and decision to collect a lot of good ideas and suggestions, by all sectors of the community alike. Second, start Municipal Government Affairs Hall built. On May 11, we built and launched the city-government lobby, were settled in 12 departments, strict implementation of first asking duty system, service system, system of gratuitous, "receiving, internal coordination, head of the window handle, limited time concluded" one-stop service. By the end of today to accept various types of 3,273, originally of up to 100%. Running Government Affairs Hall, the convenience of the masses, promoting open Government, improve the investment environment and solve their practical problems, and so did a lot of work, masses, serve the community for the Government to play a very good "window, link, model". Third, create a city government public affairs network. We rely on the Government Web site, was completed on May 24, the province's first public affairs network. Over 从上面的排列还可以看出:倍数随截面的增大而减小。在倍数转变的交界处，误差稍大些。比如截面25与35是四倍与三倍的分界处，25属四倍的范围，但靠近向三倍变化的一侧，它按口诀是四倍，即100安，但实际不到四倍(按手册为97安)，而35则相反，按口诀是三倍，即105安，实际则是117安，不过这对使用的影响并不大。当然，若能“胸中有数”，在选择导线截面时，25的不让它满到100安，35的则可以略为超过105安便更准确了。同样，2.5平方毫米的导线位置在五倍的最始(左)端，实际便不止五倍(最大可达20安以上)，不过为了减少导线内的电能损耗，通常都不用到这么大，手册中一般也只标12安。 ?从这以下，口诀便是对条件改变的处理。本名“穿管、温度，八、九折”是指:若是穿管敷设(包括槽板等敷设，即导线加有保护套层，不明露的)，按?计算后，再打八折(乘0.8)。若环境温度超过25?，应按?计算后再打九折(乘0.9)。关于环境温度，按规定是指夏天最热月的平均最高温度。实际上，温度是变动的，一般情况下，它影响导体截流并不很大。因此，只对某些高温车间或较热地区超过25?较多时，才考虑打折扣。 还有一种情况是两种条件都改变(穿管又温度较高)，则按?计算后打八折，再打九折。或者简单地一次打七折计算(即0.8*0.9=0.72,约为0.7)。这也可以说是“穿管、温度，八、九折”的意思。 例如:(铝芯绝缘线) 10平方毫米的，穿管(八折)， 40安(10*5*0.8=40) 高温(九折) 45安(10*5*0.9=45) 穿管又高温(七折) feel free to listen to their voices and help the masses solve problems, we were officially opened on May 10 "12345" Mayor calls, formulated rules and regulations, equipped with a full-time staff, a 24-hour on-duty system, people to call to receive, reply, action, reminders, feedback and so on. By year end, handled the crowd calls 1076, 94.7% feedback rate. By Mayor calls active coordination to solve a large number of bears on the immediate interests of the people and issues of great lives, but also for leadership research and decision to collect a lot of good ideas and suggestions, by all sectors of the community alike. Second, start Municipal Government Affairs Hall built. On May 11, we built and launched the city-government lobby, were settled in 12 departments, strict implementation of first asking duty system, service system, system of gratuitous, "receiving, internal coordination, head of the window handle, limited time concluded" one-stop service. By the end of today to accept various types of 3,273, originally of up to 100%. Running Government Affairs Hall, the convenience of the masses, promoting open Government, improve the investment environment and solve their practical problems, and so did a lot of work, masses, serve the community for the Government to play a very good "window, link, model". Third, create a city government public affairs network. We rely on the Government Web site, was completed on May 24, the province's first public affairs network. Over 35安(10*5*0.7=35安) 95平方毫米的，穿管(八折) 190安(95*2.5*0.8=190) 高温(九折) 214安(95*2.5*0.9=213.8) 穿管又高温(七折) 166安(95*2.5*0.7=166.3) ? 对于裸铝线的截流量,口诀指出“裸线加一半”，即按?计算后再一半(乘1.5)。这是指同样截面的铝芯绝缘芯与裸铝线比较，截流量可加一半。【例1】 16平方毫米裸铝线， 96安(16*4*1.5=96) 高温， 86安(16*4*1.5*0.9=86.4) 【例2】 35平方毫米裸铝线, 158安(35*3*1.5=157.5) 【例3】 120平方毫米裸铝线, 360安(120*2*1.5=360) ?对于铜导线的截流量,口诀指出“铜线升级算”，即将铜导线的截面按截面排列顺序提升一级，再按相应的铝线条件计算。 【例1】 35平方毫米裸铜线25?。升级为50平方毫米，再按50平方毫米裸铝线，25?计算为225安(50*3*1.5)。 【例2】 16平方毫米铜绝缘线25?。按25平方毫米铝绝缘线的相同条件，计算为100安(25*4)。 【例3】 95平方毫米铜绝缘线25? ，穿管。按120平方毫米铝绝缘线的相同条件，计算为192安(120*2*0.8)。 附带说一下:对于电缆，口诀中没有介绍。一般直接埋地的高压电缆，大体上可采用?中的有关倍数直接计算，比如35平方毫米高压铠装铝芯电缆埋地敷设的截feel free to listen to their voices and help the masses solve problems, we were officially opened on May 10 "12345" Mayor calls, formulated rules and regulations, equipped with a full-time staff, a 24-hour on-duty system, people to call to receive, reply, action, reminders, feedback and so on. By year end, handled the crowd calls 1076, 94.7% feedback rate. By Mayor calls active coordination to solve a large number of bears on the immediate interests of the people and issues of great lives, but also for leadership research and decision to collect a lot of good ideas and suggestions, by all sectors of the community alike. Second, start Municipal Government Affairs Hall built. On May 11, we built and launched the city-government lobby, were settled in 12 departments, strict implementation of first asking duty system, service system, system of gratuitous, "receiving, internal coordination, head of the window handle, limited time concluded" one-stop service. By the end of today to accept various types of 3,273, originally of up to 100%. Running Government Affairs Hall, the convenience of the masses, promoting open Government, improve the investment environment and solve their practical problems, and so did a lot of work, masses, serve the community for the Government to play a very good "window, link, model". Third, create a city government public affairs network. We rely on the Government Web site, was completed on May 24, the province's first public affairs network. Over 流量约为105安(35*3)。95平方毫米的约为238安(95*2.5)。 下面这个估算口诀和上面的有异曲同工之处: 二点五下乘以九，往上减一顺号走。 三十五乘三点五，双双成组减点五。 条件有变加折算，高温九折铜升级。 穿管根数二三四，八七六折满载流。2.5平方*9 4平方*8 6平方*7 10平方*6 16平方*5 25平方*4 35平方*3.5 50和70平方*3 95和120平方*2.5 ..................... 最后说明一下用电流估算截面的适用于近电源(负荷离电源不远),电压降适用于长距离 feel free to listen to their voices and help the masses solve problems, we were officially opened on May 10 "12345" Mayor calls, formulated rules and regulations, equipped with a full-time staff, a 24-hour on-duty system, people to call to receive, reply, action, reminders, feedback and so on. By year end, handled the crowd calls 1076, 94.7% feedback rate. By Mayor calls active coordination to solve a large number of bears on the immediate interests of the people and issues of great lives, but also for leadership research and decision to collect a lot of good ideas and suggestions, by all sectors of the community alike. Second, start Municipal Government Affairs Hall built. On May 11, we built and launched the city-government lobby, were settled in 12 departments, strict implementation of first asking duty system, service system, system of gratuitous, "receiving, internal coordination, head of the window handle, limited time concluded" one-stop service. By the end of today to accept various types of 3,273, originally of up to 100%. Running Government Affairs Hall, the convenience of the masses, promoting open Government, improve the investment environment and solve their practical problems, and so did a lot of work, masses, serve the community for the Government to play a very good "window, link, model". Third, create a city government public affairs network. We rely on the Government Web site, was completed on May 24, the province's first public affairs network. Over