28 埋地电缆碾压试验

28 埋地电缆碾压试验

28.1 An average of at least 500 lbf or 2224 N or 227 kgf shall be required for crushing finished Type BMU,and BLU cables to the point that electrical contact occurs in each of two sets of tests as described in 28.2-28.20. Cables without a ²U²in their type letters are not to be tested

.用平均至少500磅力（即2224牛顿即227千克力）对BMU型号和BLU型号的成品电缆进行碾压测试，直到28.2—28.0所中描述的那样，电触头在每两组测试中都出现。电缆印子中没有字母“U”的不用测试。

28.2 The test cable is to consist of the complete finished cable, not parts of the cable before final assembly. 28.2 待测电缆必须是成品电缆，还未进行最后装配的电缆不能作为待测电缆。

28.3 The test cable is to contain a single solid-dielectric or air-gap coaxial member with or without two or more insulated conductors for the test of the coaxial member (28.10 – 28.14) and with two or more insulated conductors for the test of the insulated conductors (28.15 – 28.20). The performance of a given construction in these tests is to be taken as representative of the performance in these tests of all other underground cables of the same construction that contain more conductors / coaxial members of the same size or that contain an equal or greater number of larger conductors / coaxial members. 28.3 待测电缆要包含一根实心绝缘或发泡绝缘，可以带有或不带有2根或以上的含绝缘导体，用于28.10-28.14中的电缆测试。带有2根或以上的含绝缘导体的电缆用于28.15-28.20的测试。指定结构的性能

将作为其他要测试的同一结构带有更多同尺寸导体或同轴电缆再或者包含相同或更多更大尺寸的导体的埋地电缆的代表。

28.4 The performance in these tests of the conductors / coaxial members in a round underground cable is to be taken as representative of the performance in these tests of the same conductors / coaxial members in both round and flat underground cables. 圆形埋地电缆中导体或整根同轴电缆的性能将作为相同尺寸的圆形和扁平埋地电缆中导体或同轴电缆的代表。

28.5 The crushing is to take place between a flat, horizontal steel plate and a solid steel rod mounted on a second, identical plate that is parallel to and below the first plate. The rod is to be bolted or otherwise secured to the upper face of the lower plate. The longitudinal axes of the plates and the rod are to be in the same vertical plane. Each plate is to be 2 inches or 50 mm wide. The rod is to be 3/4 inch or 19 mm in diameter. The plates and rod are to be at least 6 inches or 150 mm long. 该测试将在两块由实心钢条支撑的平整且相平行的钢板中进行。钢条要拴紧或者要安全地固定在第一块钢板上。钢条要与钢板垂直。每一块钢板宽度在2英寸即50毫米。钢条直径大约在3/4英寸即19毫米。钢板和钢条长度至少在6英寸即150毫米。

28.6 The crushing is to be achieved by the action of a compression machine whose jaws move the plates together or apart at the rate of 0.50 ±0.05 in/min or 10 ±1 mm/min. 该碾压测试由一台压力机执行。压力机以0.50±0.05英寸/分 即10±1毫米/分的速率用其开口将钢板夹在一起或者将钢板分离。

28.7 The cable is to be tested in two sets of ten 24-inch or 610-mm sections

cut from 20-foot or 6.1-m lengths of the finished cable. In each set, the points at which the cable is to be crushed are to be measured and then marked using chalk, ink, or another innocuous means. The test points are to be marked before the cable is cut into sections. The first mark is to be placed 12 inches or 305 mm from one end of the cable and the nine remaining marks are to be placed at succeeding intervals of 24 inches or 610 mm down the length of the cable. In reference to the position of the first mark, the second mark is to be rotated 90° around the circumference of the cable. Each remaining mark is to be rotated an additional 90° around the cable without reversing the direction of rotation at any point. Once the test points have been marked, the cable is to be cut into the ten 24-inch or 610-mm test lengths starting 24 inches or 610mm from one end. The marked test points are to be at the center of each test length.

测验分两组进行，分别从6.1米长的成品电缆中减10段610毫米长度的电缆。每一组测试中，要进行碾压测试的部分用粉笔，墨水或其他方法做好测量标记。在剪下电缆前就要做好标记点。第一个标记做在离电缆起始端305毫米处，剩余9个标记点做在随后的每610毫米间隔处。根据第一个标记点的位置，第二个点需要绕着电缆的圆周旋转90°。剩下的每个点都需要绕着电缆旋转90°，但不能颠倒任何一点的旋转方向。一旦测试点都标记好，这根电缆就可以剪成10段610毫米长的小段开始每段的测试。所标记的测试点需要在每根测试长度的中心。

28.8 The specimens, the apparatus, and the surrounding air are to be in thermal equilibrium with one another at a temperature of 23.0 ±5.0°C (73.4 ±9.0°F) throughout the test. 在整个测试中，所有的样本，仪器和周围的空气需要保持在热平衡状态，温度在23.0±5.0℃（73.4±9.0℉）。

28.9 The plates are to be electrically connected together, to the metal of the testing machine, and to earth ground. 钢板需要进行电气联接，与测试机器的金属部分和地面都联接。

28.10 TEST OF THE COAXIAL MEMBER – For each of the test lengths in the first set, the center conductor of the coaxial member is to be connected to the earth-ground connection of the testing machine and the outer conductor of the coaxial member is to be connected in series with a buzzer, bell, lamp, light-emitting diode (LED) with a current-limiting resistor, or other indicator to one terminal of a battery or other power supply of less than 30 volts. The other terminal of the battery or power supply is to be connected to the earth-ground connection of the testing machine. Any insulated conductors in the cable are to be ignored for this test. 同轴电缆测试——第一组中每一段的待测电缆，其内导体要与测试机器的地面连接件联接，外导体要与蜂音器，闹铃，灯泡，和发光二极管，该二极管要带有限流电阻器或其他联接电池一极的指示器或其他小于30伏特电压的电源供应器。蓄电池的另一极或者该电源供应器要与测试机器的地面连接件相连。电缆中任何含绝缘的内导体在此测试中将被忽

28.11 The cable at the first test mark is to be placed and held on the steel rod, with the longitudinal axis of the cable horizontal, perpendicular to the longitudinal axis of the rod, and in the vertical plane that laterally bisects the upper and lower plates and the rod.第一个点测试时，电缆应水平放在竖直钢条上并与竖直钢条垂直，且垂直平面中的上下板和钢条保持同等距离。

28.12 The upper plate is to be made snug against the cable.电缆测试部分须与上

钢板相接触。

28.13 The upper plate is to be moved downward at the rate specified in 28.6 increasing the force on the cable until electrical contact occurs between the center and outer conductors, between the outer conductor and the earth-grounded metal of the machine, or both as signaled by the indicator sounding or lighting. The force at which the contact occurs is to be recorded for the first test point.根据28.6所述的速率，将上钢板往下移，挤压电缆，直到内外导体之间，外导体和与测试机器的地面连接件之间产生电接点或机器发出了声音或提示灯亮时才停止。记录电接点出现时所需的力为第一个测试结果。

28.14 Each of the remaining test lengths is to be crushed at the mark. The force at each test point is to be recorded. The coaxial member complies and the test is to be discontinued in the event that each of the first three recorded crushing values equals or exceeds 1000 lbf or 4448 N or 454 kgf. Otherwise, all ten test lengths are to be crushed and the sum of the ten recorded forces is to be divided by 10 to obtain the average crushing force for the cable. The coaxial member does not comply where the average of the ten forces is less than specified in 28.1.

一一测试剩下标志点的挤压测试。每个测试点的力都需记录。如果前三个挤压值等于或超过了1000lbf或4448牛或454kgf，内外导体挤压测试合格，无需再继续进行测试。否则，10个测试点都要一一挤压测试，记录并总和测试结果，再除以10，算出平均值。如果10个值的平均值小于28.1节所列值，则该内外导体未通过测试。

28.15 TEST OF THE INSULATED CONDUCTORS – The test cable is to contain

two or more insulated conductors in addition to the coaxial member. For each of the test lengths in the second set, each of the insulated conductors is to be connected in series with a buzzer, bell, lamp, light-emitting diode (LED) with a current-limiting resistor, or other indicator to one terminal of a battery or other power supply of less than 30 volts. The other terminals of the batteries or power supplies are to be connected together. The coaxial member in the cable is to be ignored for this test.

带绝缘的内导体测试-测试电缆须包括两个或多个带绝缘内导体。第二部分测试中，每个带绝缘内导体要与测试机器的地面连接件联接，外导体要与蜂音器，闹铃，灯泡，和发光二极管，该二极管要带有限流电阻器或其他联接电池一极的指示器或其他小于30伏特电压的电源供应器。蓄电池的另一极或者该电源供应器要与测试机器的地面连接件相连。在此测试中，无需测试外导体部分。

28.16 The cable at the first test mark is to be placed and held on the steel rod, with the longitudinal axis of the cable horizontal, perpendicular to the longitudinal axis of the rod, and in the vertical plane that laterally bisects the upper and lower plates and the rod. .第一个点测试时，电缆应水平放在竖直钢条上并与竖直钢条垂直，且平分了垂直平面中的上下板和钢条

28.17 The upper plate is to be made snug against the cable.电缆测试部分须与上钢板相接触。

28.18 The upper plate is to be moved downward at the rate specified in 28.6 increasing the force on the cable until electrical contact occurs between two or

more of the insulated conductors as signaled by the indicators for each of the shorted conductors sounding or lighting. The force at which the contact occurs is to be recorded for the first test point.

根据28.6所述的速率，将上钢板往下移，挤压电缆，直到两个或多个带绝缘内导体之间产生电接点并发出声音或提示灯亮时。记录电接点出现时所需的力为第一个测试结果。

28.19 Each of the remaining test lengths is to be crushed at the mark. The force at each test point is to be recorded. The insulated conductors comply and the test is to be discontinued in the event that each of the first three recorded crushing values equals or exceeds 1000 lbf or 4448 N or 454 kgf. Otherwise, all ten test lengths are to be crushed and the sum of the ten recorded forces is to be divided by 10 to obtain the average crushing force for the cable. The insulated conductors do not comply where the average of the ten forces is less than specified in 28.1.

一一测试剩下标志点的挤压测试。每个测试点的力都需记录。如果前三个挤压值等于或超过了1000lbf或4448牛或454kgf，带绝缘内导体挤压测试合格，无需再继续进行测试。否则，10个测试点都要一一挤压测试，记录并总和测试结果，再除以10以获得平均值。如果10个值的平均值小于28.1节所列值，则该带绝缘内导体挤压未通过测试。

28.20 The overall cable does not comply unless both the coaxial member and the insulated conductors comply.

除非内外导体挤压测试和只带绝缘内导体挤压测试都合格，这根电缆挤压测试才能算

合格。