1.Before determining cable faults, testers must first determine the nature of the cable fault in order to adopt appropriate working and testing methods, in addition to mastering the performance and operation methods of the machine. Firstly, use a megohmmeter or multimeter to measure the insulation resistance between each phase and ground at one end of the cable. Determine whether it is a low resistance short circuit, open circuit, or high resistance flashover fault based on the resistance value.
2.When the resistance value is below 100 ohms, it is a low resistance fault; 0 to tens of ohms is a short circuit fault; and when the resistance value is extremely high to infinity, it is an open circuit or disconnection fault. Whether the cable is disconnected can also be confirmed by connecting the cable terminal to a multimeter and measuring the resistance values of the two short circuited phases at the starting end. This type of fault can be directly measured using the low pulse method.
3.When the resistance value is very high (several hundred megahertz and one gigabit) and there is instantaneous discharge during high-voltage testing, this type of fault is generally called flashover fault, which can be determined by DC high-voltage flashover method.
4. If the resistance value of a high resistance fault is higher than that of a low resistance fault, it can be determined using the DC high-voltage flash test method during high-voltage experiments.
5. Roughly test in a certain way before determining the point, and if necessary, find the cable path and measure the length or distance of the cable.