HV bridge method 7500V Power Cable Outer Sheath Fault Tester

Introduction
The cable outer sheath fault tester XHHG521A is designed based on the MURRAY bridge principle and can be used to locate the breakdown points of various wires and cables and the defect points that have no breakdown but low insulation resistance values.

The equipment uses an electric voltage regulator and an R-type transformer to form a high-voltage constant current source, and the button operation can increase or decrease the voltage. The no-load voltage is 7500V, the short-circuit current is 100mA, and a high-sensitivity amplifier and galvanometer are used to indicate balance. It forms a balanced bridge with a proportional potentiometer, and the whole is placed at a high potential. The measurement cable is a specially designed two-core high-voltage rubber cable. The four-terminal resistance measurement method is used to avoid errors caused by lead resistance. The entire panel is at low potential. One-touch operation, enter the cable length and automatically calculate the fault distance. The high voltage source and bridge are integrated in a portable protective box. Therefore, the device has high voltage, light weight, easy operation and safe use.

High voltage bridges are particularly suitable for
1. The high-resistance breakdown point of the cable after laying, especially the linear high-resistance breakdown point that is difficult to burn into low resistance, such as the linear high-resistance breakdown of the cable intermediate joint.
2. Flashover type breakdown point. After breakdown, the constant current source can maintain the arc, a stable current flows through the bridge, and the bridge has sufficient sensitivity.
3. Defects that have not yet broken down but have low resistance, such as insulation defects found with a megohmmeter that have low cable resistance but do not break down under the operating voltage.