XHGG501E

At a glance

What it measures

The instrument answers one question: how far along the cable is the fault. It does that by timing a reflection and multiplying by the propagation velocity of the cable under test, so the number it gives you is a distance along the conductor, not a distance across the ground.

• Distance to fault from the test end, on ranges from 300 m to 65 km.
• Cable length from the open-circuit reflection at the far end — useful on its own when drawings and reality disagree.
• Propagation velocity measured on a cable of known length, so an unfamiliar cable can be characterised before it is relied on.
• Waveform record of every measurement, stored on the instrument and exportable, so the interpretation can be reviewed rather than remembered.

How it locates the fault

Three acquisition modes cover the fault types that actually occur. The choice is not a preference: a low-voltage pulse will not see a fault that only conducts at 10 kV, and a flashover method on a dead short tells you nothing a pulse could not.

• Low-voltage pulse (TDR). A 100 V pulse is launched into the cable and the reflection from any impedance change is timed. Reads open circuits, breaks, dead shorts and low-resistance faults, and gives cable length and velocity.
• Impulse current. An external surge generator drives the cable to flashover at the fault; the instrument captures the current transient through a coupler and times the travelling wave. This is the workhorse method for high-resistance faults.
• Decay. The cable is charged through an external DC source until the fault breaks down, and the instrument captures the resulting oscillation. Suits faults that only break down at high voltage and will not hold a stable arc.

Key features

• Automatic ranging and waveform analysis. The instrument selects a test range and proposes the fault distance, which is the difference between a five-minute measurement and a training course.
• Velocity presets with a user-defined entry. XLPE, PVC, oil-impregnated and rubber-insulated cables are pre-set; anything else is entered directly or measured on a known length.
• Continuous sampling. The waveform is captured on every shot rather than on command, so a fault that only flashes over once is not missed.
• Touch and encoder control. Cursors can be driven either way — the encoder matters when the screen is wet or the operator is gloved.
• Waveform library. More than 8,000 low-voltage pulse and flashover records are held on the instrument and exported over USB for archiving alongside the job.
• Full English menu. Confirmed on the delivered firmware, not a translation of the brochure.

Technical specification

Where it fits

• Distribution cable faults on XLPE, PVC and oil-impregnated cables, including service and street lighting circuits.
• Length and route verification where records are incomplete — often the first honest measurement on an inherited network.
• Communications and coaxial cable where the fault is an impedance change rather than an insulation failure.

Pre-location gives a distance. Turning that distance into a mark on the ground is a separate job with separate equipment — see the XHDD503E cable fault pinpointer. The two instruments are normally bought and used together, with a surge generator between them.