Wire and cable fault side search method

The first thing to determine the fault types: "high impedance" or "low resistance" We're going to do different according to different fault types of fault location method. How to distinguish the high rent or a low resistance?Insulation resistance.High resistance and low resistance wire and cable without a very clear definition of value, usually 100 k under the considered low resistance, more than 100 k o considered high resistance.

Book a fault We according to the different fault types, using different methods to due to a fault, first of all get the approximate location of fault point.

Then we'll point fault accurately Before the precise point, we also need to know the detailed information of the fault cable laying we won't be able to arrive according to the value of preoperative near point of failure.If there is this kind of situation, we need to use beforehand "path" to determine the path of the cable, use range to determine the approximate location of the fault point.And then to be able to accurately fixed point.

If it is a high impedance fault, we should use "shock" to accurately fixed point, first by a high voltage pulse generator, at a certain time interval to shoot fault cable, high voltage pulse and fault point will be breakdown and continuous discharge.We by detecting the fault point discharge signals for accurate positioning.At this time we need a "precision" designated instrument, its principle is "magnetic acoustic time difference method", precisely: at the time of discharge cable is two signals, one is the electromagnetic signal, a signal is the sound of the discharge.Two signals from the point of failure due to the different velocity of propagation, reaches the receiver when there is a "time lag", like thunder when we see the lighting first and then hear the sound, we can accurately by judging the "time lag" positioning fault - lag the smallest place point of failure.

If it is a low resistance fault, we all know that low resistance grounding fault failure and even death, because of the low to ground resistance, discharge could not make it happen, we need the other way - "audio method".Using a powerful audio generator fault cable to a fixed frequency audio signal, and then use audio detector along the cable route.Due to very low resistance at fault point, the signal current will be here into the earth, look from the detector, reach the point of failure, the signal can suddenly become very small or even disappear.At this point we can locate the fault point.

At this time we can excavation flexible cables, dig the cable, after cutting to do joint fault section, do the pressure test, all OK, put into operation. But need clear confirmation when truncation cable fault cable, if errors occur, the consequences.