NOYAFA Electronic specializing in testing instruments and cable testers for 16 years
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NOYAFA Electronic specializing in testing instruments and cable testers for 16 years
The cable is the "path" of electrical transmission, and we can now say that it has been inseparable from our eating, working, contacting, communicating, and always around the electricity. As the transmission "path", it is also "sick", when these cables are electrically transmitted“path”And we can now say that it has been inseparable from electricity, from our eating, work, contact, communication, always around the electricity. Transmission transmission“path”Also“Get ill”When these“Pathogenesis”When electricity, electricity can not be transmitted. When there is a failure, you need to use a cable fault tester.
The working principle of the cable fault tester mainly includes three parts: power cable fault detection host, cable fault tester, cable tester and cable path instrument. The cable fault tester host is used to measure cable fault characteristics, length, and cable failure point. The cable fault tester is based on the cable fault tester, determine the correct position of the cable fault point, and determine the accurate position of the cable fault point.
For unknown to the buried cable, you need to use a roadrier to determine the underground direction of the cable. The basic method of cable failure detection is to apply a high pressure pulse to the fault cable, and the failure point occurs, and generate electromagnetic waves outside the electromagnetic wave-around fault point, simultaneous sound. Arc reflection method, also called Secondary pulse method: working principle in cable fault tester: first applies a certain voltage level and a high pressure pulse of a certain amount of energy to the cable test, so that the cable test ends to faultless cables, so that the cable failure Click on the arc.
At the same time, the low voltage pulse of the measurement is added to the test end, and when the pulse is measured to reach the high flame retardant point of the cable, the arc is encountered and reflected in the arc surface. When the high-resistance failure is turned into a transient short-circuit fault, the low voltage measurement pulse will produce a significant change in impedance characteristics, so that the flashing measurement waveform is made of low-voltage pulse short-circuit waveform, so that the waveform is particularly simple. This is called secondary pulse method.
The waveform of the low voltage pulse reflected wave received is the same as the entire surface of the surface. After the high voltage pulse is released, the low-pressure pulse wave generated by the unsealed high pressure pulse is superimposed, and a dispersion point will occur in 2 waveforms, that is, the reflective waveform of the fault point. The method of combining a low voltage pulse method and the high-pressure flashing technology makes the tester more easily determine the position of the fault point.
The secondary pulse method is more advanced than the traditional test method. It simplifies the complex waveform in the high-pressure flashing method into a relatively simple low-pressure pulse short-circuit fault waveform, so it is very simple to determine the failure distance. The three pulse method extends the filling time and the steady arc method, and it is convenient to position high-resistance faults and flashback failures. Three pulse method technology advanced, simple operation, clear waveform, fast and accurate, is currently the mainstream method of high resistance and flashing fault positioning.
The three pulse method is the improvement of the secondary pulse method. It is the first to measure the reflection waveform of the low pressure pulse with a cable fault tester in the case of not hit the cable failure point, and then use high pressure pulse to do a cable fault point. When the arc voltage drops to a certain value to stabilize and extend the arc time, then the low pressure pulse is issued, the reflection waveform of the fault point is obtained, and the two waveforms can also be found that the divergent point is the reflective waveform of the fault point. The stable and extension time of the arc pulse is achieved by the medium pressure pulse, which is easier to obtain a waveform of the fault point than the secondary pulse method. Compared with the second pulse method, the three pulse method does not need to select the synchronization time of the arc, and the operation is relatively simple.
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