Cable Sheath Fault Locator Murray Bridge Tester 5600V 100mA High Resistance | XHHG521B

The XHHG521B cable sheath fault locator is a high-voltage bridge cable fault tester designed based on the principle of the Murray bridge. It can be used to locate the breakdown points of various wires and cables after laying, as well as defect points that have not broken down but show low insulation resistance. It can also be used to locate defective points of various cables in the cable factory, making it an essential tool for cable maintenance and repair.

The device uses an electric voltage regulator and an R-type transformer to form a high-voltage constant current source, with keypad control for raising and lowering the voltage. With an open-circuit voltage of 5600V and a short-circuit current of 100mA, it uses a high-sensitivity amplifier and galvanometer for balance indication, forming a balanced bridge with the ratio potentiometer, all placed at high potential. The measuring cable is a specially designed double-core high-voltage rubber cable, and the four-terminal resistance measurement method avoids errors introduced by lead resistance. The panel is entirely at low potential for operator safety.

The instrument is equipped with an LCD display and one-key operation: input the cable length and the fault distance is calculated automatically. The high-voltage source and the bridge are integrated in one portable protective case, giving the device high voltage, light weight, convenient operation and safe use.

The XHHG521B is especially suitable for three types of cable faults that are difficult for other methods to handle reliably.

The cable fault location bridge method works as follows: short-circuit the faulty phase of the tested cable with a healthy phase, connect the two arms of the bridge to the faulty phase and the healthy phase respectively, and adjust the adjustable resistor on one arm of the bridge until the bridge is balanced. Using the ratio relationship and the known cable length, the fault distance can be obtained.

If the distances from the two ends of the tested cable to the breakdown point are L1 and L2, the total cable length is L, and the corresponding core resistances are R1 and R2, then after the bridge is balanced, the reading P (in percent) directly gives the fault position: L1 = P% · L. The Murray bridge method for breakdown point location is a classic approach that is convenient and accurate. Its basis is that the core (or shield) resistance is uniform and proportional to the length. The bridge method is relatively simple and its accuracy meets field engineering test requirements, making it especially convenient for two-phase short-circuit faults of cable lines.

When the auxiliary cable has the same cross-section as the faulty cable, the fault position is X = 2 × L × P1%. Pay special attention to the factor "2", because connecting the auxiliary cable doubles the cable length participating in the calculation.

When the auxiliary cable has a different cross-section, convert it to the faulty cable length: if the fault cross-section is Sx and the auxiliary cable cross-section is S, then X = P1% × (1 + Sx/S) × L.

If all three cores of a three-core cable are broken down or short-circuited to each other, select the core with the best insulation resistance as the auxiliary cable. For the reverse-connection check, lower the voltage, discharge, swap the measuring clips, repeat the measurement to get P2, and verify P1 + P2 = 100.

Every XHHG521B is delivered with the host, a high-power jumper cable set, a power cord, a ground wire, a charger and 5 spare fuses (3A), and is backed by one-year free warranty and lifetime maintenance and technical service. For ordering, training and after-sales support, please contact our sales team.