BS EN IEC 61125:2018

What is BS EN IEC 61125-Test methods for oxidation stability of insulating liquids about? 

BS EN IEC 61125 is an international standard that discusses insulating liquids and test methods to determine their oxidation stability. The main objective of BS EN IEC 61125 is to provide manufacturers of lubricating oil with accurate indications on the quality of their products. 

BS EN IEC 61125 describes a test method for evaluating the oxidation stability of insulating liquids in the delivered state under accelerated conditions regardless of whether or not antioxidant additives are present. 

Who is BS EN IEC 61125-Test methods for oxidation stability of insulating liquids for? 

BS EN IEC 61125 on test methods for oxidation stability is relevant to: 

• Manufacturers of insulating liquids 
• Manufacturers of equipment and machinery using insulating liquids 
• Electrical engineering industry 
• Mechanical and electrical engineers 
• Quality control and testing agencies 

Why should you use BS EN IEC 61125-Test methods for oxidation stability of insulating liquids? 

Oxidation stability specifies the ability of an insulating liquid to withstand oxidation under thermal stress and in the presence of oxygen and a copper catalyst. 

For BS EN IEC 61125-compliant testing, the insulating liquid sample is maintained at 120 °C in the presence of a solid copper catalyst whilst bubbling air at a constant flow. The degree of oxidation stability is estimated by measurement of volatile acidity, soluble acidity, sludge, dielectric dissipation factor, or from the time to develop a given amount of volatile acidity. 

BS EN IEC 61125 covers a test method for evaluating the oxidation stability of inhibited mineral insulating oils in the delivered state by measurement of the induction period with oxygen. This method is only intended for quality control purposes. 

BS EN IEC 61125 also covers a test method intended to simulate the thermo-oxidative behaviour of ester insulating liquids. 

Overall, if you are a manufacturer, conducting test methods in compliance with BS EN IEC 61125 can ensure quality, and thus service-life of the lubricant is not reduced.  

What’s changed since the last update? 

BS EN IEC 61125:2018 supersedes BS EN 61125:1993, which is withdrawn. This edition includes the following significant technical changes with respect to the previous edition: 

• The title has been modified to include insulating liquids different from mineral insulating oils 
• The method applies for insulating liquids in the delivered state 
• Former Method C is now the main normative method 
• Precision data of the main normative method has been updated concerning the dissipation factor