Cable faults · Medium voltage
Cable fault location on medium-voltage cables in Bavaria and Baden-Württemberg
A faulted medium-voltage feeder costs money by the hour: reconfigured networks, idle plants, customers on a makeshift supply. CFT narrows the fault down, brings the position at the surface to the point and hands over a report that lets civil works and cable fitters move in deliberately. Report the feeder on +49 (0) 173 6842932 or at office@cft-de.de – switching state and access are agreed before the appointment.
What we do on site
On medium voltage, high-resistance faults without an echo in the reflectogram dominate. Every job therefore starts with the condition measurement: insulation and resistance decide whether prelocation can start directly or the fault has to be conditioned first. What the measurement means for switching state and supply is settled before the appointment – not at the measuring point.
Key facts at a glance
| Methods | Insulation and resistance measurement, Time domain reflectometry with surge current coupling, Ley effect, Surge and burn-down to make the fault earth-sensitive, Sheath fault location on plastic-sheathed cables, Cable identification in the trench |
|---|---|
| Application range | Buried medium-voltage cables in distribution networks, industrial networks and on industrial premises, including joints and terminations |
| Duration | Two hours to one day, depending on the number of faults |
| Result format | Damage report as a PDF |
| Service area | Bavaria and Baden-Württemberg from our Erding base – CFT Group Deutschland GmbH, Lange Zeile 27, D-85435 Erding |
For you as a business
In the medium-voltage network, location decides not just where to dig but how long the outage lasts: the sooner the position is fixed, the shorter the network runs in back-feed. And because high-resistance faults like to strike again when voltage returns, proper diagnosis is part of the job – which core, which fault type, which joint. A report that records this also carries the discussion with the cable manufacturer or the civil contractor when the cause is disputed.
How the job runs
- You report the fault; switching measures, earthing and access to the cable ends are agreed together before the appointment.
- The condition measurement determines fault type and affected cores.
- High-resistance faults are conditioned until they answer the prelocation; the time domain measurement with surge current coupling gives the distance.
- Pinpointing via the voltage gradient brings the position at the surface to the point; where several cables share the trench, cable identification secures the right line.
- You receive the damage report as a PDF – with diagnosis, readings and the marked excavation spot.
Equipment and methods
Prelocation works with time domain reflectometry and surge current coupling, which makes even high-resistance breakdowns visible. High-resistance faults are burned down by the surge generator until they are earth-sensitive; pinpointing via the voltage gradient then leads to the spot. On plastic-sheathed cables, sheath fault location is added – it finds jacket damage that would become the next outage, before it is one.
What you receive
The marked excavation spot and an auditable damage report as a PDF: fault type, affected cores, methods, readings and position. Civil works and cable fitters can be tasked precisely, and the fault is documented towards third parties.
Costs and effort
We charge by deployment time from Erding. The measuring time depends on the fault type: a low-resistance fault is prelocated quickly, a high-resistance one needs conditioning. For network operators with recurring demand we offer per-incident terms.
Frequently asked questions
How long is the feeder down during the measurement?
Completely, for the duration of the measurement – we measure on the isolated, earthed cable. What that means for switching and supply belongs before the appointment; we tell you in advance which steps take how long.
The fault only strikes sporadically under load – will the measurement still find it?
Yes. Intermittent faults are burned down under surge voltage until they answer reliably earth-sensitive; then they can be measured. Sporadic does not mean unfindable – it only means diagnosis comes first.
Does CFT also locate sheath faults before they become an outage?
Yes. Sheath fault location finds damage to the outer jacket of plastic-sheathed cables – worthwhile after civil works along the route or as a follow-up measurement on a section with recurring faults.
Does CFT carry out switching operations in the network?
No. Switching, isolation and earthing remain with the network operator or your authorised switching personnel; we measure on the released cable. That coordination happens before the appointment.
Describe the findings.
The more precisely you describe the findings, the more directly we can go to work. Plans, readings and photos help us settle the method in advance.
What happens next
- We read your message and match the case to a method.
- We come back to you – usually with a question that shortens the appointment.
- We confirm the appointment and what it costs before anyone sets off.
Rather talk?
+49 (0) 173 6842932
Describe your case.
Fastest by telephone – then we settle straight away which method fits and what you should prepare.
Or write to office@cft-de.de.