Transformer Oil Filtration and Testing Method

Transformer oil filtration

PURPOSE Transformer oil filtration :

In electrical system require annual analysis of transformer oil testing based on the aspect of Color, Dielectric breakdown voltage, Dissolved metals, Flash point, fire point, Interfacial tension, Liquid power factor, Oxidation inhibitor content, Polychlorinated biphenyls content, Visual examination and this type of maintenance procedure which help us to ensure that they are operating safely and with an most advantageous effectiveness. For the time being, maintaining transformer oil testing too crucial to pass up or diminish the risk factor. This aspect obviously plays an important role to eliminate the fire possibility at Auto Accessories Limited. On the other hand on time electrical maintenance increases system survival and ensure trouble free services. The insulation oil of voltage- and current-transformers fulfills the purpose of insulating as well as cooling. Thus, the dielectric quality of transformer oil is a matter of secure operation of a transformer. As transformer oil deteriorates through aging and moisture ingress, transformer oil should, depending on economics, transformer duty and other factors, be tested annually. Voltage breakdown during oil test Transformer oil testing sequences and procedures are defined by various international standards. Power utility companies have a vested interest in periodic oil testing since transformers represent a large proportion of their total assets.
Through such testing, transformers’ life can be substantially increased, thus delaying new investment of replacement transformer assets. aaaa


Applies to own transformer (Converting high voltage to low tension side voltage) situated at Auto Accessories Ltd. sub-station room which actually the key of distribution in all Electrical Panel Board / distribution board at Auto Accessories Ltd.


The fault free operation of power transformers is a factor of major economic importance and safety in power supply utilities and industrial consumers of electricity. In the current economic climate, Industries/Supply Utilities tighten their control on capital spending and make cutbacks in maintenance; an increased awareness is placed on the reliability of the existing electric power supply. Down time is at a premium. Often, the loading is increase on present units, as this will defer purchasing additional plant capacity. Thus the stress on the transformer increases. The net total effect of the thermal, electrical and mechanical stress brought on by increased service needs to be monitored to ensure reliability. Regular sampling and testing of insulation oil taken from transformers is a valuable technique in a preventative maintenance program. If a proactive approach is adopted based on the condition of the transformer oil, the life of the transformer can be extended.


Asst. Manager, Jr. Manager, Sr. Supervisor, Supervisor of Maintenance Department and the analyzing personnel from the transformer analyzing


Preventive Maintenance:Maintenance manager Make a defensive Maintenance Record due to this aspect.

Maintenance record (shown as follows) has exercised to annual basis of frequency (Frequency of inspection: Annually)

  5.2      Wellbeing of session:   

Maintenance personnel should be used to the followings when transformer oil analysis conducted by the third party:

  • Know how to treat victims of electrification during XF5 oil testing period.
  • Before working on transformer oil testing ensures that REB power (11KVA) is shutting down.
  • Wearing all type of safety appliance (which needed in this perspective) and factory personnel must ensures the appearance of safety. In case of emergency, if work is necessary on Power-ON-lines (i.e. Hot line)
  • While electrical work is going on post a sign stating “do not switch on power” as an instance:
    LOTO mechanism.
  • Ensuring the calibrated testing equipment of oil analysis to the factory representative.
  • Factory representative must ensure the adequate manpower in sense of helping hand during the data acquisition process.
  • Don’t make any unusual situation during testing period.
  • Maintenance personnel must wear the electrical safety shoes and electrical graded hand gloves to
  • conduct as a helping hand. Core Scheme of testing:
  • The transformer oil is filled in the vessel of the testing device. Two standard-compliant test electrodes with a typical clearance of 2.5 mm are surrounded by the dielectric oil.
  • A test voltage is applied to the electrodes and is continuously increased up to the breakdown voltage with a constant, standard-compliant slew rate of e.g. 2 kV/s.
  • At a certain voltage level breakdown occurs in an electric arc, leading to a collapse of the test voltage.
  • An instant after ignition of the arc, the test voltage is switched off automatically by the testing device. Ultra fast switch off is highly desirable, as the carbonisation due to the electric arc must be limited to keep the additional pollution as low as possible.
  • The transformer oil testing device measures and reports the root mean square value of the breakdown voltage. WE sale Manufacturing Accounting Software
  • After the transformer oil test is completed, the insulation oil is stirred automatically and the test sequence is performed repeatedly. (Typically 5 Repetitions, depending on the standar Conclusion: The lower the resulting breakdown voltage, the poorer the quality of the transformer oil!

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