Power cable fault distance problems in testing and processing & # 65288; The first phase of the & # 65289;
it is well known that regardless of any product in the production and processing of the unexpected breakdown of the process will inevitably appear some problems, failure problems need to solve, of course, AnWei power company small make up today will give you about power cable fault distance problems and processing methods of test. Five period, we speak of power cable fault distance can be found below problems in testing and processing, The first phase) See below, and the specific content.
fault point not breakdown
in blunt flash test, inexperienced people often think the ball discharge gap, the point of failure and discharge at the same time; Or think that as long as the ball discharge gap, can detect the waveform, in fact, both views are one-sided. Ball clearance breakdown, depends on the size of the ball gap distance and the level of the applied voltage. The greater the distance, the higher the breakdown voltage required to breakdown when added to the cable and the higher the voltage. And breakdown of fault point or not is depends on the size of the fault resistance and the impact of high and low voltage cable, with a fault resistance of fault point, if the gap is too small ball, the ball clearance breakdown when added to the voltage on the cable is very low, even may be too low to ionization breakdown point of failure.
to determine whether a point of failure flash-over breakdown discharge method basically has the following two kinds.
1) by detecting high voltage rectifier circuits of current judge whether the point of failure flashover discharge breakdown. Generally speaking, the discharge current is not more than 10 ma, the point of failure has not been breakdown; When the discharge current is greater than 20 ma, fault point has flashover breakdown; Discharge current in 10 - When 20 ma, often characterized by inadequate discharge. Point of failure is fully discharging, ball gap discharge are loud and crisp.
(2) by observing the flash test waveform measurement instrument to determine whether the fault point flashover discharge breakdown. Flash method for straight, if the point of failure flashover discharge, the instrument will be displayed on the screen straight waveform, otherwise will without any waveform display. For punching method, the fault point breakdown, not only on measured waveform terminal reflection pulse, without fault point discharge pulse. When fault point discharge is imperfect, the screen will appear some irregular waveform, rather than the cosine oscillation waveform.
when the point of failure does not discharge or incomplete discharge, will cause trouble-free reflection waveform or waveform is irregular, bring ranging work difficult. Then, can consider to increase the impact discharge energy. Increase the electric capacity and improve the impulse voltage all can increase impact discharge energy, when the electric capacity is large enough ( Not less than 4 uf) , improve the effect of impulse voltage is obvious.