DIAGNOSTIC OF OLTC IN POWER TRANSFORMERScompare
According to the data of one of the leading engineering companies of the electrical industry (State Trust for the Organization and Rationalization of Regional Power Plants and Networks) 13.5% of 35-750 kV transformer malfunctions are caused by OLTC. The researches of "Krasnoyarskenergo" - the branch of PJSC "IDGC of Siberia" have shown that more than 23% of all damages of 35 kV transformers are connected to the OLTC malfunctions.
One of the causes of OLTC damage is the operational disorder of contactors and switching devices, contact burning of contactors, closing switches mechanisms jamming, loss of mechanical strength of steel parts and paper-bakelite shaft.
In order to identify the origin of OLTC fault and to automate the diagnostic process, SKB EP company presents 2 specialized diagnosic instruments: PKR-2M and PKR-2, the basic function of which is the ability to generate oscillograms of contactors with the use of demountable and non-demountable (DRM) methods and record circular diagrams by three phases simultaneously. The results are displayed in graphical or tabular form.
Milli-ohmmeters MIKO-9A and MIKO-8M(A) are equipped with the additional mode for OLTC diagnostic using the DRM method. The instruments are designed to measure electrical resistance in inductive objects, but in this direction, it is possible to carry out a phase-by-phase OLTC diagnostic using the non-demountable DRM method with the result shown in the form of oscillograms.
methods (DRM mode)