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The CFT-35 is used with a voltmeter/phaser for testing installed or repaired underground cable prior to energizing it. Only cable with extruded dielectric such as rubber or polyethylene can be tested with the CFT-35. Using the CFT-35 on paper insulated cable may provide erroneous test results caused by higher leakage currents typical for this type of cable.
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In practice, the CFT-35 rectifies the high voltage from the source, usually a transformer primary, and charges up the cable, shown as a capacitor above. When a connection is first made, the DC from the CFT-35 will charge up the cable capacitance through the resistors in the meter sticks. If the cable is good, current will stop flowing when the cable is charged up. If the cable is not good, the cable will not charge and current will continue to flow, as indicated by a higher meter indication.
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The following equipment is required for testing cable with a CFT-35:
1) An HD Electric two-stick voltmeter/phaser.
2) The CFT-35 Cable Fault Tester.
3) For deadfront applications, ASP bushing probe(s) or, for live front applications, GCP-1probe(s). An EA-15/25 elbow probe may also be used for deadfront applications.
4) For deadfront applications, a feed-through bushing may also be used.
HD Electric CFT-35 电缆故障测试探头
CFT-35 与电压表/移相器一起使用，用于在通电之前测试已安装或修复的地下电缆。只能使用 CFT-35 测试带有挤压电介质（如橡胶或聚乙烯）的电缆。在纸绝缘电缆上使用 CFT-35 可能会提供由于此类电缆典型的较高泄漏电流而导致的错误测试结果。
实际上，CFT-35 对来自电源（通常是变压器初级）的高压进行整流，并为电缆充电，如上图所示。首次连接时，来自 CFT-35 的直流电将通过仪表棒中的电阻器为电缆电容充电。如果电缆良好，当电缆充电时电流将停止流动。如果电缆不好，电缆将不会充电，电流将继续流动，如更高的仪表指示所示。
使用 CFT-35 测试电缆需要以下设备：
1) HD Electric 两杆式电压表/移相器。
2) CFT-35 电缆故障测试仪。
3) 对于死前应用，ASP 套管探头，或者，对于带电前端应用，GCP-1 探头。 EA-15/25 弯头探头也可用于死角应用。
4) 对于死角应用，也可以使用馈通套管。
