What is the Sufficient Gas Concentration Required to use Doernenburg Ratio and Rogers Ratio Methods of DGA?
Analysis of dissolve gasses in the transformer oil can be done using various methods. Two of those methods are Doernenburg Ratio and Rogers Ratio methods.
One of our readers who downloaded our tool for the DGA using the methods mentioned had the following question;
Dear sir,
I download the excel sheet for DGA from your website.
But I am confuse about enough gas concentration. So please tell me what are the specified lmits on which the ratio are calculate for analysis?
For colomn in excel sheet in Dorenerburg Ratio Method i.e. How enough gas concentration are come to true or false? Cell no B14 & B17. What is B14 & B17. Actullly the row number for calculating enough gas concentration are hide. So I cant understand the calculating of enough gas concentration? This is for my knowledgae and customer point of view.Beacause customer ask for enough gas concentartion.
Please provide the full excel sheet about Rogers Ratio and dorerenburg ratio method
I am waiting for your helpful replay.
Best Regards
Chetan Patil
The tool that we developed is based on the IEEE Std C57.104-1991 or the IEEE Guide for the Interpretation of Gases Generated in Oil-Immersed Transformers, which also explains how the two methods work. We just simplified the use method using excel work sheet. To answer the question, the minimum concentration of gas required to make the analysis valid is as follow;
• For Doernenburg Ratio Method, the concentration of at least one of the gasses, Hydrogen (C2), Methane (CH4), Acethylene (C2H2), and Ethylene (C2H4) must be at least twice as high as its limit (2L); AND at least one of the gasses Ethane (C2H6) and Carbon Monoxide (CO) must exceed its limit (L). Concentration limit (L) of the mentioned gasses is as follow;o
- Hydrogen (H2): 100 ppm
- Methane (CH4): 120 ppm
- Carbon Monoxide: 350 ppm
- Acethylene (C2H2): 35 ppm
- Ethylene (C2H4): 50 ppm
- Ethane (C2H6): 65 ppm
• For Rogers Ratio Method, same limit as for the Doernenburg Ratio Method
I hope this helped
Filed in: Transformers
Local date: March, 2010
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