Knowing whether a distribution transformer can be re-energised after a storm or a line fault only takes a go/no-go tester that checks its windings de-energised and without disconnecting the secondary loads. The ADOC-3 does it in a single test of about 60 seconds by contact on the primary bushings: it detects short-circuits and open circuits in the primary and short-circuits in the secondary of transformers from 1 kVA to 3 MVA and 1000 V to 50 kV, and shows the result as short-circuit, correct or open by LED and audible signal.
ADOC-3 key data
- Diagnosis: the ADOC-3 detects short-circuits and open circuits in the primary winding and short-circuits in the secondary, and classifies the transformer into three states — short-circuit, correct or open — with no numerical values to interpret.
- Transformer range: 1 kVA to 3 MVA and 1000 V to 50 kV rated voltage, with single-phase, Delta or Yn primary: pole-mounted units, three-phase banks, pad-mount transformers and dry-type MV units.
- Measurement: low voltage, AC and DC, across 3 channels by contact on the primary bushings, with the secondary loads connected; a single test of about 60 seconds covers all windings.
- Indication: high-brightness LEDs and an audible signal for each of the three states.
- Reading reliability: automatic self-test at power-on and a self-check mode for the integrity of the measurement leads.
- Power supply: 4 alkaline AA batteries, 1.5 V, compatible with rechargeable NiMH batteries, for 8 hours of measurement; automatic shutdown after 15 minutes and a low-battery indicator.
- Ruggedness: IP40 / IK06 enclosure with rubber boot, magnetic strap for fixing to the tank and an operating temperature of -20°C to +60°C.
- Size: 177 × 89 × 45 mm and 0.47 kg, in a semi-rigid case; optional accessories: 1.5 m spare lead, 11 × 21 × 30 cm rigid case and elbow adapter pins.
Advantages
Clear three-state diagnosis
The tester detects short-circuits and open circuits in the primary winding together with short-circuits in the secondary, and reports the result as short-circuit, correct or open through bright LEDs and an audible tone, with no waveform to interpret.
Testing without disconnecting the secondary
Measurement is taken by contact on the primary bushings while the secondary windings stay connected to their loads; a single test covers every winding, so a unit can be checked in roughly a minute.
Confidence before re-energising
After a line fault or a storm, the tester establishes whether a transformer can be reconnected without risking a violent failure once it is put back under load.
Coverage of every distribution layout
Three measurement channels handle single-phase transformers, three-phase banks, Yn and Delta couplings, pole-mounted units, pad-mount transformers and dry-type medium-voltage units, from 1000 V to 50 kV and 1 kVA to 3 MVA.
Compact and self-sufficient in the field
At 0.47 kg and 177 × 89 × 45 mm, the unit runs on four AA batteries for eight hours of measurement, checks the integrity of its own leads before each campaign and switches off automatically after 15 minutes of inactivity.
Applications
- Checking distribution transformers after a storm or a line fault, before re-closing.
- Inspection campaigns on overhead networks and distribution substations.
- Testing de-energised three-phase banks, pad-mount transformers and dry-type medium-voltage units.
- Workshop receiving inspection before commissioning.
About the product
The IP40 enclosure, rated IK06 against impact, operates from -20°C to +60°C and is wrapped in a rubber boot that absorbs drops and splashes; a magnetic strap holds the unit against the transformer tank so the operator can work hands-free. The removable measurement leads store on a hook-and-loop strap and can be checked at any time using the built-in self-check mode, which flags a damaged cable before it causes a false reading.
The complete kit ships in a semi-rigid case with the clip-ended leads, and a low-battery indicator combines with automatic shutdown to extend the life of the four AA cells. Available accessories: a spare 1.5 m measurement lead, a rigid transport case, and a set of adapter pins for transformer elbows.
Technical specifications
| Detection | Short-circuit, correct, open circuit |
| Primary configurations | Single-phase, Delta, Yn |
| Rated transformer voltage | 1000 V to 50 kV |
| Transformer power | 1 kVA to 3 MVA |
| Measurement channels | 3 |
| Power supply | 4 AA batteries; 8 hours of measurement |
| Operating temperature | -20°C to +60°C |
| Dimensions and weight | 177 × 89 × 45 mm; 0.47 kg |
| Result indication | Audible and visual (high-brightness LED) |
| Measurement type | Low voltage, AC and DC, by contact on the primary bushings |
| Protection ratings | IP40; IK06 |
Frequently asked questions
Which transformer voltages and power ratings does the ADOC-3 cover?
The ADOC-3 tests de-energised distribution transformers from 1 kVA to 3 MVA and 1000 V to 50 kV rated voltage, with single-phase, Delta or Yn primary; it covers pole-mounted units, three-phase banks, pad-mount transformers and dry-type MV units.
Does the ADOC-3 run on rechargeable batteries, and how long do they last?
Yes. The ADOC-3 is powered by 4 alkaline AA 1.5 V batteries and is compatible with rechargeable NiMH batteries; it provides 8 hours of measurement, switches off by itself after 15 minutes of inactivity and warns with a low-battery indicator.
Do the secondary loads need to be disconnected before the test?
No. The ADOC-3 measures with the secondary windings still connected to their loads; only contact with the primary bushings is required.
What does a go/no-go result mean?
The tester does not output a value to interpret. It classifies the transformer into one of three states — short-circuit, correct or open circuit — shown by LED and confirmed by an audible signal.
Does it work on three-phase banks?
Yes. Its three channels cover single-phase transformers as well as three-phase banks in Yn or Delta coupling, including pad-mount units.
How is the condition of the measurement leads verified?
A built-in self-check mode confirms the integrity of the leads before the test, which prevents a false diagnosis caused by a damaged cable.
How long does a check take?
About 60 seconds: a single test verifies every winding and the transformer's status is displayed immediately.
