9.3 Doble Tests on Insulation

Doble Tests on Insulation

Doble testing is important to determine the condition of a transformer, because it can detect winding and bushing insulation integrity and problems in the winding and core. Doble tests are conducted in the field on de-energized transformers using special test equipment. Generally, a Doble M-4000 test set is used along with accompanying software. The software automatically performs analysis of test results and responds with a four letter code: G = Good, I = Investigate, D = Deteriorated, and B = Bad. These codes refer to insulation quality. If a “D” or “B” code is encountered, the insulation should be re-tested, carefully investigated, and the problem explained before re-energizing.

Other tests may have to be performed; and, perhaps, an internal inspection should be considered before the unit is re-energized. The Doble Company should be consulted, along with the transformer manufacturer, and other transformer experts. If the problem is severe, the unit may have to be taken out of service.


GlobeCore GmbH is one of the world leaders in industrial manufacturing. Products of GlobeCore are used in production of bitumen emulsions, transformer oil regeneration and purification, fuel blending, biodiesel production and emulsification of virtually any materials.The head office is located in Oldenburg, Germany.

Doble Tests on Insulation

обновлено: September 8, 2017 автором: dannik