Last updated: 2019-05-29
Transformer Oil Sampling
Silver Solutions service engineers have been trained and certified by Rotek Engineering - A devision of Eskom, in the strict routines needed to obtain a clean oil sample.
Just as a blood test provides a doctor with a wealth of information about the health of a patient, a sample of transformer oil, taken correctly, can tell service engineers a great deal about the condition of a transformer.
Oil is used both to cool the transformer and to insulate internal components. Because it bathes every internal component, the oil contains a great deal of diagnostic information. So a laboratory analysis of a sample can provide advance warning of developing conditions such as tapchanger arcing.
However, the information generated from the oil analysis is only as good as the sample itself. Silver Solutions service engineers have been trained in the strict routines needed to obtain a clean sample. These include: taking a sample while the oil is warm, and measuring the temperature so that the laboratory can then adjust the results for moisture content: pre-flushing the sample leg and running the oil quietly into a clean vessel to minimise degassing: and sealing the sample securely.
The best information is obtained by viewing trends. So it is useful to take a benchmark sample when a transformer is first energised, or when an oil treatment is performed, and to take further samples at regular intervals so that any variation in quality can be identified to indicate developing faults.
Typical tests carried out during the laboratory analysis of an oil sample include:
- Breakdown voltage (dielectric strength)
- Moisture content
- Dissolved gas analysis
- Full Test (Water, KV, Acid, DGA)
- Normal Test (Kv, Water, Acid)
- PCB Exact Count (PPM)
- Furanics Test
- Tan Delta and Interfacial Tension as well as others