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Transformer Oil Analysis

Transformer Oil Sampling

Transformer oil sampling should be done in order to obtain the most representative oil samples .
To ensure that the most representative samples will be obatined , transformer oil sampling should be
considered in 4 factor area as following:-
  1. Sampling Method (Sampling Procedure)
  2. Sampling Appratus (Sampling Tools and Devices)
  3. Sampling Location 
  4. Sampling Frequency


1. Sampling Method or Procedure


Transformer oil  sampling should be done in accordance with proper and standard method .
  • ASTM D3613 : Standard Practice for Sampling Electrical Insulating Oils for Gas Analysis and 
    determination of water content
  • ASTM D 923 : Standard Practice for Sampling Electrical Insulating Liquids.


2. Sampling Appratus (Sampling Tools & Devices)


As per ASTM D 3613 ,For dissolved gas analysis , use glass-syringe


Focuslab Ltd's Transformer sampling apparatus (Sampling Tools&Devices) 


3. Sampling Location


In general , mineral oil filled transformers (mineral insulated oil with relative density less than one), should 
be samples from the bottom valve .


4. Sampling Frequency


Regular- periodic -routine sampling - testing of transformer oil is a valuable technique and strategy in preventive
maintenance program and needs to be performed correctly and regularly .
Normal -Regular-periodic -Routine Sampling Frequency will be 6 month basis to a year basis 


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