1. Development history of resistance tester:

The loop resistance tester tells everyone that since the cable has been buried, the detection of the resistance tester has become a problem that must be solved. Initial cable fault roughing is performed using the bridge test principle. At that time, resistor bridge, capacitor bridge, low voltage bridge and high voltage bridge were used. Testing cable fault distance using the bridging principle was a common method in the 1960s and 1970s. In the 1970s and 1980s, cable fault testing was often performed by flash testing, which was based on pulse reflection. The instruments used are oscilloscope-type flash meters, oscilloscope-type flash meters, etc. After the 1990s, with the widespread application of computer technology, smart cable fault flash testers were put into use, and the testing principle used was still the pulse reflection method. Flash meters are used from picture tubes to liquid crystal displays, and are generally used in the control of microcontrollers, making rough testing of cable faults a new field.

2. Introducing the fixed-point method for cable faults.

There are two methods for detecting resistance testers: bridge method and pulse reflection method.

1. Sound measurement method: The use of legal points for sound measurement is the method of using cable fault fixed points from the past to the present. This is an effective approach. However, the instruments used have evolved from the simple acoustic amplifiers of the past to the acoustic and magnetic synchronized fixed-point instruments commonly used today. Sound measurement legal points apply to high voltage cables, low voltage cables, direct buried cables, cable trench cables, etc.

2. Step voltage method: The step voltage legal point is used. It is mainly used for the ground fault point where the outer sheath has insulation requirements for the cable sheath. Now for some directly buried unarmed low-voltage cables, if there is a ground fault, the legal point can be used if there is a step voltage. View.

3. Electromagnetic method and audio method: It is feasible in principle to use electromagnetic waves to fix points or use audio legal points. However, judging from the current situation, reliable nursing equipment cannot be used in practice. In other words, fixed-point instruments using electromagnetic waves are still under research and development at various research institutions and require further verification and improvement before they can reach the level of practical application.

XZT 7111 High Voltage Circuit Breaker Tester