I. Overview

   The cable outer sheath fault tester is designed based on the principle of the MURRAY bridge, and can be used to locate the breakdown points of various wires and cables after laying and the defect points that have no breakdown but low insulation resistance. Of course, it can also be used to locate the defect points of various cables in the cable factory.

The equipment adopts switching power supply to form a high-voltage constant current source, the no-load voltage is 7500V, and the short-circuit current is 40mA. It uses a high-sensitivity amplifier and a galvanometer to indicate balance, and a proportional potentiometer to form a balance bridge. The whole is placed at a high potential, and the measurement cable is specially designed. The double-core high-voltage rubber cable uses the four-terminal resistance measurement method to avoid the error introduced by the lead resistance. The cable is reliably grounded through the braided shielding layer. The operation button on the panel is at low potential, and the bridge is operated through the insulating rod. The high voltage constant current source and the bridge are integrated in a portable aluminum alloy box. Therefore, the device has high voltage, light weight, convenient operation and safe use.

Compared with the wave reflection method, the bridge balance method has no blind area, and is especially suitable for judging short cables and breakdown points near the end, and is easy to operate.

II. Product Features

Ø The output voltage is adjustable;

Ø There is no blind area in the test range;

Ø Has high precision and stability;

Ø Using high-sensitivity amplifier and galvanometer to indicate balance;

Ø Zero protection.

 The cable outer sheath fault tester is especially 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 to low resistance, such as the linear high-resistance breakdown of the cable intermediate joint.

2. Flashover type breakdown point, the constant current source can maintain the arc after the breakdown, a stable current flows through the bridge, and the bridge has sufficient sensitivity.

3. Defect points that have not yet broken down but have low resistance, such as insulation defect points that have low cable resistance but do not break down under operating voltage found by a megohmmeter.

Due to the above characteristics , the high voltage cable outer sheath fault tester is especially suitable for the following users: 

Teams engaged in professional positioning: such as cable repair and test classes for large and medium-sized power supply bureaus and large-scale power-consuming enterprises. Most of the cable breakdown points can be quickly found by the cable outer sheath fault tester . It is used in conjunction with the wave reflection method and the fixed-point instrument to learn from each other's strengths and make the positioning faster and more reliable.

1.Small users: such as small power supply bureaus and medium-sized power-consuming enterprises. There are not many cables, generally the direction is clear, not too long, and the number of faults is limited. If a set of wave reflection locator is equipped, the price is high, and the quality and experience of the user are required to be high, so it is not the best choice. It is a better way to choose the XHHG521 tester which is easy to operate and can meet daily needs.

2. Cable production plant: In the factory, it can be used to locate the breakdown point of various cables, and the digital capacitance meter can be selected to find out the break point. The device is light in weight and easy to carry to the site for positioning services for cable users.

III. Technical Parameters

1. Input voltage: AC 220V (±10%), 50 Hz± 1 Hz;

2. No-load voltage ≥ 7500V ;

3. Short-circuit current ≥ 40mA ;

4. Positioning ratio accuracy ±(0.2% L±1) meters ;