Jiapu cable tell you the common causes of power cable problems. Cable fault types can be divided into grounding, short circuit, disconnection of the three main categories of fault types are as follows:
A phase of the core wire broken or multi-phase broken wire
In the cable conductor connection experiment, the cable conductor insulation resistance and the relevant provisions of the line, but in the view of a phase or many phases can not be connected, then a phase of the core wire break or many phase breaks.
Three-core cable one or two core grounding
Three-core cable core or two core conductors with insulation shaking table test out of the connection, and then a core or two core to ground insulation resistance telemetry. If the core and the core between the existence of insulation resistance than the normal value is much lower than the value of this insulation resistance value is higher than 1000 ohms is called high resistance grounding fault; Conversely, is a low resistance grounding fault. Both of these faults are referred to as disconnected and grounded faults.
Three-phase core short circuit
Short-circuit grounding resistance size is the cable of the three-phase core short-circuit fault identification of the basis. There are two kinds of short-circuit fault: low resistance short-circuit fault, high resistance short-circuit fault. When the three-phase core short-circuit, less than 1000 ohms of ground resistance is low resistance short-circuit fault, on the contrary, is a high resistance short-circuit fault.
Cause analysis:
First: external damage
Cable problems in the external damage is the most common cause of the problem. The cable was damaged by external forces in the future will show a large area of power failure. For example, underground pipeline construction process, the cable because the construction machinery traction is too large and was pulled off; cable insulation, shielding layer due to excessive bending of the cable and damage; cable cut peeling excessive cutting and knife marks too deep. These direct external elements will form a certain damage to the cable.
Second: insulation moisture
Cable manufacturing process is not refined will lead to the cable’s protective layer cracked; cable terminal joints sealing is not; cable protection sleeve in the cable used by the object pierced or perhaps suffered corrosion. These are the main reasons for the cable insulation moisture. At the moment, the insulation resistance drops, the current increases, triggering power problems.
Three: chemical corrosion
Long-term current action will let the cable insulation occurs a lot of heat. If the cable insulation work for a long time in a poor chemical environment will change its physical properties, so that the cable insulation aging and even lose effect, power problems will occur.
Four: long-term overload operation
Cable long-term high-current operation in the environment, if the line insulation layer has impurities or aging, coupled with external factors such as lightning and other over voltage impact, overloading occurs a lot of heat, it is very easy to present cable problems.
Post time: Oct-10-2023