Go from an observed fault symptom to a ranked list of likely causes and the first checks to make.
Enter what you see at the CCR and on the airfield, plus any readings you have. The tool scores each likely cause against your observations and lists the first checks for the strongest ones. It narrows the search. It does not replace testing, the manufacturer's manual or your site procedures.
Measured output current at the CCR. Within 5 % of the set current counts as matching.
The minimum is a placeholder. Use your own site or manufacturer limit.
| # | Likely cause | Likelihood | First checks |
|---|
The logic is simple scoring, so a result can be checked by hand.
Your menu choices are combined with the readings. A measured current within 5 % of the set current counts as matching, otherwise low or high. Insulation resistance below your minimum counts as low.
Every cause has points for the observations that support it. The points are added, and causes with no supporting observation are dropped.
Most likely is a score within 80 % of the top score. Possible is within 50 %. Below that is less likely. If even the top score is low, the tool says more information is needed.
Each cause lists the first checks to make. Every check assumes the circuit is isolated first.
| Item | Value |
|---|---|
| Whole circuit out, open-circuit alarm | Observed |
| Excavation on the route | Recent event |
| 0 A measured against 6.6 A set | Current low |
| Open circuit in the loop | Score 12, most likely |
| Next causes | Much lower scores |
It does not locate a fault, read CCR logs or measure anything. The weights are planning judgement, and several faults can be present at once. For load and voltage questions use Calculators #14, #15 and #16.
Quick answers on how fault symptoms are scored into a ranked list of likely causes and first checks.
It takes you from an observed fault symptom to a ranked list of likely causes and the first checks to make. You enter what you see at the CCR and on the airfield, plus any readings, and the tool scores each likely cause against your observations and lists first checks for the strongest ones. It narrows the search and does not replace testing, the manufacturer's manual or your site procedures.
Series circuits carry high voltage at up to several amps. Isolate and lock out the CCR before touching any cable, connector or transformer, never open a live series loop, and follow your site's safe-working procedure. Stop and escalate if you see heat, smoke, arcing or a burning smell. Every first check also assumes the circuit is isolated first.
The main symptom (such as lights out, a CCR that will not start, low or high circuit current, flicker, wrong brightness at a step, or low insulation resistance), the CCR alarm, which lights are out, a recent event such as rain, excavation, lightning or a settings change, and when the fault happens. Readings are optional but sharpen the result.
Menu choices are combined with the readings into facts. A measured current within 5 % of the set current counts as matching, otherwise low or high, and an insulation resistance below your minimum counts as low. Each cause has points for the observations that support it, so Score = Σ points for each matching observation, and causes with no supporting observation are dropped.
Most likely is a score within 80 % of the top score, possible is within 50 %, and below that is less likely. If even the top score is low, the tool says more information is needed. In the worked example, a whole circuit out with an open-circuit alarm after excavation and 0 A measured against 6.6 A set gives an open circuit in the loop as most likely, with a score of 12.
No. The ranking comes from planning weights, not measured fault statistics, and the weights are planning judgement. Treat it as a place to start looking. Several faults can be present at once, and the insulation minimum you enter is a placeholder for your own site or manufacturer limit.
It does not locate a fault, read CCR logs or measure anything. For load and voltage questions use Calculators #14, #15 and #16. Fault finding shall follow the equipment manufacturers' manuals and your site's safe-working procedures.
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