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 power cable is a device buried underground. Under normal circumstances, the soil layer plays a protective role in the cable. But once failed, it is very difficult to find, it takes a lot of time, and it is a lot of waste to manpower and material. In this case, the power cable is required to be a device buried underground. In general, the soil layer protects the cable.
But once failed, it is very difficult to find, it takes a lot of time, and it is a lot of waste to manpower and material. In this case, you need to use cable fault detection equipment, such as a power cable fault tester. Common failed cable initial testing is divided into control loop bridge balancing method, bottom pressure single pulse reflective surface method, flash detecting instrument method, in the first test of cable faults, first according to common fault characteristics, adopt suitable cable fault detection The instrument is used to accurately measure and measure the common fault point from the relative path part of the common fault point.
The key to the primary test method has three types of control circuit bridge balance method, under pressure single pulse reflection surface and flash detectors. The method of improving the current meter can modify the DC power amplifier before the current meter, but the gain value of the amplifier has caused a more serious zero drift condition and thereby causing the electric bridge to be balanced. The working voltage of the rising bridge switching power supply must relatively improve the compression strength of the bridge body and the safety precautions to maintain the actual operation staff. When the switching power supply work voltage rises to a certain value, common fault resistors are generally mainly The case where the grounding wire resistance suddenly decreases to zero, and the pressure is damaged by all the electric bridges.
Common power cable fault tester usage. The characteristics and provisions of the bridge method are: only applicable server downtime in the cable line line, if there are many common fault points in the route, it is not possible. The higher the bridging of the other end of the cable line, the higher the cross section, and the cross section of the cable wire electrical conductor is adjacent, and the joint is tightened, and its contact resistor is close to zero.
Improve the experimental working voltage is a high resistor grounding device fault test, it is important to prompt the problem. After using a common fault, a common fault is converted into a grounding device. It is necessary to accurately measure the method of electricity bridge method immediately to prevent the insulating layer to restore the common fault point. You don't have to put the ground wire resistance of common faults is too low, and the sound is too small when it is used to prevent the measurement point method.
The bottom pressure single pulse reflective surface method, is known for a single pulse method, and is the basic principle of the wave impedance non-matching point to cause the wave impedance non-matching point when the differential signal is spread in the cable line. Single pulse wave reflection is measured by the digital oscilloscope. The surface time and cable speed, and clarify the spacing of the cable fault point. In general, the characteristic impedance in the cable line is unpaid, except that the open electrical conductors are disconnected (air), the short-circuit fault, and the grounding device are commonly fault, and the cable joint and cable cross the metal material pipeline, etc., the characteristic impedance is uniform. Point, like the reflective surface of the wave, must be carefully identified. In particular, when the grounding wire resistance value exceeds about 2 to 3 times or so, the fluctuation amplitude value of the reflective surface is not large, and the common fault point cannot be identified.
Single pulse method is the most suitable for determination, it is often used, and the ground-to-ground resistance is less than 100.ΩCable failure. The above is the method of use and precautions for the use of the power cable fault tester, hoping to bring a certain help to those in need.
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