买3008记者帮砍价汽车周刊记者.ppt

* * * * * * * * * * * * * * * * Conductor Size Example #2 Using the table method, determine the size of copper conductor that should be used to provide electrical service to a livestock building that is located 65 feet from the source. The service is 120 V and the estimated load for the building is 35 amps. UF-B cable and a 2% voltage drop will be used. First determine minimum size based on ampacity. = Second: determine size based on VD = AWG #8 AWG 6 * Conductor Size Example #3 Determine by calculation, using the standard equation, the size of conductor that will be required to provide service to a 120 V, 1-1/2 hp water pump that is located 250 feet from its source. The conductors with be copper and directly buried. A 2% voltage drop is acceptable. The motor has a power factor of 0.70. The standard equation for copper requires values for amperage, voltage and length. The load on the circuit, amperage, must be determined first. 1 hp = 746 watts, but when determining conductor sizes for electric motors it is common practice to use 1,000 watts per horsepower. * Conductor size #3--cont. For this circuit with a 8.75 amp load, the circular mills of the conductors can be determined by: The conductor size is: #6 = 26,240 cmil #8 = 16,510 cmil. Size (AWG) Area (cmil) 14 4110 12 6530 10 10380 8 16510 6 26240 4 41740 3 52620 2 66360 Which size should be used? * Conductor Sizing Conclusion For short distances, ampacity determines the minimum conductor size. For long distances, voltage drop determines the minimum size. Because long and short are relative terms, both ampacity and voltage drop must be checked when sizing conductors. * Questions ? 精品资料网（）成立于2004年，专注于企业管理培训。 提供60万企业管理资料下载，详情查看：/map.htm 提供5万集管理视频课程下载，详情查看：/zz/ 提供2万GB高清管理视频课程硬盘拷贝，详情查看：/shop/ 2万GB高清管理视频课程目录下载：/12000GB.rar 高清课程可提供免费体验，如有需要请于我们联系。 咨询电话：020值班手机网站网址： 在线文档： * * 120 V is RMS voltage. Utilities try to keep it within this range. Brown out—extremely harmful for electric m