Distribution transformer tester ADOC-3

Go/no-go tester for distribution transformers from 1 kVA to 3 MVA

The ADOC-3 checks the windings of a de-energised distribution transformer in a single test and indicates within about 60 seconds whether the unit can be safely returned to service.

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

Frequently asked questions

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.