Diagnostic of RNOA type OLTC device with PKR-2M and MIKO-9A

In the middle of September, SKB EP specialists conducted an on-site diagnostic of OLTC device of RNOA type as a part of cooperation with RES, LLC.

Technical condition of the OLTC was evaluated with the use of transformer OLTC diagnostic system PKR-2M and advanced precision milli-ohmmeter MIKO-9A.

PKR-2M is designed for OLTC diagnostic both resistor and reactor type. The instrument allows you to obtain circular diagrams and generate oscillograms simultaneously by three phases. During work at this facility, circular diagrams and oscillograms were obtained with demountable check mode. In order to assess the object condition and identify the causes of existing problems in OLTC operation contact probes were used. According to the diagnostic results, the discrepancy between obtained and nominal values, as well as the violation of contact switching sequence of selector were revealed.

MIKO-9A milli-ohmmeter was used to measure DC resistance. Due to its functional features the measurement process was convenient and fast.

MIKO-9A is designed to measure DC resistance in inductive and non-inductive circuits in the range of 1 µΩ – 30 kΩ with test current up to 10 A. Additionally, the device has special DRM mode for OLTC diagnostic without removing contactor tank cover, as well as demagnetization and "Heat Run Test" functions. In addition, the milli-ohmmeter makes it possible to connect to three phases of the transformer simultaneously and take measurements with automatic switching between them, what reduces the total amount of measurements.

All the results of this work, including identified malfunctions and received data were given to RES, LLC employees in order to conduct RNOA type OLTC repair.

If you work with OLTC of any type and would like to learn more about the on-site diagnostic service for your facility, you may send a request on SKB EP website or contact us via phone +7 (812) 500-25-48 or e-mail skb@skbep.com.

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