GE Hydran 201 i Instruction Manual page 215

Other parameters (transformer load, oil temperature, dissolved gas analysis [DGA]) can
also be useful in interpreting the gas level and trend evolutions. This information can even
be used to comment the historic data (see the Hydran Host Software Manual).
An excellent source of information on the interpretation of gases in oil is the IEEE Standard
C57.104-1991 "Guide for the Interpretation of Gases in Oil-Immersed Transformers."
When interpreting the data of the Hydran 201i System, take the following points in consid-
eration:
• An alarm can be triggered because of a misadjusted alarm set point. The historic data file
Events indicates the modifications to the parameter settings (see Section 11.2.2 on
page 11-6).
• An alarm (example: Low gas level) can be triggered following some maintenance
procedure on the transformer, such as vacuum degassing of the oil.
• Daily load cycles and intermittent transformer operations both affect the Hydran 201Ti's
gas level and hourly trend readings.
Part 17997 Rev. 6, March 2011
Data Analysis
11-7