Cable Sheath Fault Tester | Murray Bridge Cable Fault Locator | XHHG521B
Product Description
XZH TEST XHHG521B is designed for cable sheath fault locating. This high-voltage bridge cable fault tester is 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, and the defect points with no breakdown but low insulation resistance. Of course, it can also be used to locate the defective points of various cables in the cable factory.
The device uses an electric voltage regulator and an R-type transformer to form a high-voltage constant-current source, with push-button operation for voltage increase and decrease. It uses a high-sensitivity amplifier and a galvanometer to indicate balance, forming a balanced bridge with a proportional potentiometer, all at high potential. The panel is maintained at low potential, and the four-terminal resistance measurement method eliminates errors introduced by lead resistance.
Applications & Target Audience: Engineered for cable installation and jointing contractors, municipal power grid maintenance crews, industrial plant electrical teams, and cable manufacturers' quality control departments that need to locate high-resistance breakdown points, flashover breakdown points and low-insulation defects in power cable sheaths without measurement blind spots.
Product Features
Output voltage is adjustable;
With higher precision and stability;
Uses a high-sensitivity amplifier and galvanometer to indicate balance;
Zero-position protection;
Automatically detects the fault point, but retains manual testing functionality.
Key Functions
The high-resistance breakdown point of the cable after laying, especially the linear high-impedance breakdown point that is difficult to burn down to low resistance, such as the linear high-resistance breakdown of the middle connector of the cable.
Flashover type breakdown point: after the breakdown, the constant current source can maintain the arc, there is a stable current through the bridge, and the bridge has sufficient sensitivity.
The defect point that has not broken down but has low resistance, such as the insulation defect point where the megohmmeter finds low cable resistance but the operating voltage does not break down.
Technical Parameters
| Parameter |
Specification |
| Product name |
Cable sheath fault locator XHHG521B |
| No-load voltage |
≥5600V |
| Short circuit current |
≥100mA (5-40mA recommended for balancing) |
| Positioning accuracy |
±(0.2%·L±1) meters |
| Weight |
25kg |
| Working power supply |
AC 220V(±10%), 50Hz±1Hz; internal battery 6.4V, DC 8.4V charging port |
| Measurement method |
Murray bridge, four-terminal resistance measurement eliminates lead resistance errors |
| Measurement cable |
Specially designed two-core high-voltage rubber cable |
| Display |
12806 display, one-button operation, automatic fault distance calculation |
| Protection |
Portable protective case, panel maintained at low potential |
Compared with the wave reflection method, the bridge balancing method has no blind spots and is particularly suitable for determining the breakdown point in short cables or near the cable end.
Application Scenarios
| Application Scenario |
Typical Applications |
| Cable Installation & Jointing Contractors |
Locating high-resistance breakdown points at intermediate joints and verifying sheath integrity after installation |
| Municipal Power Grid Maintenance |
Locating sheath breakdown and low-insulation defects in urban distribution cables without blind spots |
| Industrial Plant Electrical Teams |
Testing power cable insulation after laying and during routine preventive maintenance |
| Cable Manufacturers (QC) |
Locating defective points of various cables in the cable factory before delivery |
Precautions for Use and Common Faults
- Do not touch the high-voltage connecting cables or the cable under test during testing to avoid high-voltage injury.
- Do not power on the instrument while connecting cables; turn off the power immediately after the test is completed.
- The instrument cannot be started unless the voltage adjustment control is at the zero position.
- Operation requires the presence of at least two people: one to handle connections and the other to verify them; the test may only begin after everything has been confirmed correct.
- The instrument's grounding terminal must be reliably grounded using a dedicated grounding cable; preferably, connect it to points such as a test site grounding post, an electrical cabinet grounding busbar, or the base of a piece of machinery.
- During the test and after its completion, and before anyone touches high-voltage components, the system must be discharged, and the grounding wire must be attached.
- Automatic fault distance calculation must be performed while the voltage is not raised (i.e., before applying high voltage).
FAQ
Q1: Who is this cable sheath fault tester designed for?
It is designed for cable installation and jointing contractors, municipal power grid maintenance crews, industrial plant electrical teams, and cable manufacturers' quality control departments that need to locate breakdown points and insulation defects in power cable sheaths.
Q2: What is the Murray bridge method and why choose it?
The Murray bridge method shorts the fault phase and the healthy phase of the cable at the far end, then balances the bridge arms to calculate the fault distance from the ratio and the known cable length. Compared with the wave reflection method, it has no blind spots and is especially suitable for short cables or breakdown points near the cable end, with accuracy meeting on-site engineering requirements.
Q3: What fault types can the XHHG521B locate?
It locates high-resistance breakdown points after cable laying, especially linear high-resistance breakdown points that are difficult to burn down to low resistance such as intermediate cable joints; flashover-type breakdown points where the constant current source maintains the arc after breakdown; and low-resistance insulation defects that have not yet broken down under operating voltage.
Q4: What are the key technical specifications of the XHHG521B?
It provides a no-load voltage of ≥5600V, a short-circuit current of ≥100mA (5-40mA recommended for balancing), positioning accuracy of ±(0.2%·L±1)m, a weight of 25kg, and works from AC 220V(±10%) 50Hz±1Hz with an internal battery. The four-terminal resistance measurement method eliminates errors introduced by lead resistance.
Q5: What safety precautions and after-sales service are provided?
Always operate with at least two people, never touch high-voltage cables during testing, keep the grounding terminal reliably grounded, and discharge the system before touching any high-voltage parts. The instrument is guaranteed free of charge for product quality problems within one year from the date of purchase, with lifelong maintenance and technical services.
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