What Is the AGE Additive and Which Transformers Require AGE Testing?

This is Part 1 of a two-part series on AGE testing in transformer insulating liquids. Here we will cover what AGE is and where testing does and does not apply. In Part 2, we will discuss the AGE test itself, how results are interpreted, and typical recommendations based on those results.

What Is the AGE Additive?

AGE is an abbreviation for allyl glycidyl ether — pronounced as the individual letters A-G-E, not like the word “age.” AGE is a chemical additive used in some perchloroethylene-based insulating liquids.

Role as an acid scavenger in perchloroethylene fluid

The purpose of the AGE additive is to act as an acid scavenger when these liquids are used as permanent retrofill fluids for Askarel (PCB) transformers. As perchloroethylene fluid ages in service, it breaks down and forms hydrochloric acid. The AGE additive acts to neutralize this acid so that it does not react with the metals in the transformer.

How perchloroethylene breaks down in service

When perchloroethylene fluid degrades, the byproduct is hydrochloric acid. Without an effective acid scavenger present, this acid attacks the transformer’s metal components, compromising reliability and potentially rendering the unit unserviceable.

Which Fluids Contain AGE — and Which Don’t?

AGE in perchloroethylene retrofill fluids (e.g., System 50)

The AGE additive applies to perchloroethylene-based retrofill fluids only. This type of retrofill was most commonly performed using the System 50 process — originally owned by ENSR and later by others — using perchloroethylene fluid sold under names such as System 50 Fluid, Perclene, or TransClene. Accordingly, the AGE test is appropriate for samples taken from former Askarel-filled transformers that were retrofilled with perchloroethylene fluid via this process.

Original equipment fluids with different acid scavengers (e.g., Wecosol)

Manufacturers of original equipment perchloroethylene insulating liquids addressed the prospect of fluid breakdown and acid formation differently. Wecosol, manufactured by Westinghouse, is a frequently encountered example of an original equipment perchloroethylene insulating liquid. It contained a different, proprietary acid scavenger — not AGE. Wecosol-filled units were produced by Westinghouse in the 1980s and into the early 1990s. Because original equipment fluids like Wecosol used alternative scavenger chemistry, the AGE test is not applicable to those units.

When Was Perchloroethylene Used as a Retrofill Fluid?

Temporary vs. permanent retrofill intent

Perchloroethylene was used to flush out and remove Askarel from the solid insulation of transformers so that units could be reclassified as non-PCB. However, the perchloroethylene fluid was not always intended to be the final, permanent fluid. In many cases, it was used as a temporary fluid, with the original intention of replacing it within approximately 3–12 months with a final fluid such as silicone.

Cases where final retrofill was never completed

In some cases, the final retrofill was never completed, and such units may continue to be in service still containing the “temporary” perchloroethylene fluid. Because this fluid was not intended to be permanent, it did not contain any acid scavenger. In these cases, the perchloroethylene fluid has most likely broken down and created hydrochloric acid, which has attacked the metals in the transformer — making the transformer unreliable and a candidate for replacement.

When Should the AGE Test Be Performed?

The AGE test is appropriate when it is unknown whether a given perchloroethylene-filled transformer was retrofilled with a permanent, AGE-containing fluid or a temporary fluid with no acid scavenger.

If the AGE test shows that no AGE is present in the fluid, then regardless of whether the perchloroethylene fluid was intended to be permanent, acids have most likely formed and the transformer should be considered unreliable and evaluated for replacement.

Summary:

AGE (allyl glycidyl ether) is an acid scavenger additive used in perchloroethylene-based retrofill fluids to neutralize hydrochloric acid that forms as the fluid degrades in service.

Where AGE applies — and where it doesn’t:

• Present in permanent perchloroethylene retrofill fluids used in processes such as System 50 (fluid sold as System 50 Fluid, Perclene, or TransClene)
• Not present in original equipment perchloroethylene fluids such as Wecosol (Westinghouse), which used a different proprietary acid scavenger — the AGE test is not applicable to those units

Temporary vs. permanent retrofill:

• In many PCB remediation cases, perchloroethylene was used as a temporary flushing fluid with the intention of replacing it within 3–12 months with a final fluid such as silicone
• In some cases, that final retrofill was never completed, leaving units in service with a fluid that contained no acid scavenger
• Those units are at high risk of acid-related metal degradation and should be evaluated for replacement

When to perform the AGE test:

• Appropriate when the retrofill history of a perchloroethylene-filled transformer is unknown
• If the test shows no AGE present, the transformer should be considered unreliable and evaluated for replacement — regardless of whether the fluid was intended to be permanent

In This Series:

• Part 1: What Is the AGE Additive and Which Transformers Require AGE Testing?
• Part 2: How Is the AGE Test Performed and How Are Results Interpreted?