Transformer oil management programmes
Ongoing custody of transformer oil condition across a site or fleet. A single oil test is data; a trend is a decision.
Who an oil management programme is for
A transformer oil management programme keeps the oil in every unit on a schedule: sampled, tested, trended against IEC 60422 and treated when the trend calls for it. It is for owners who would rather act on a trend than on an alarm.
IPP asset managers
Oil results trended against IEC 60422 are a reporting deliverable for lenders and owners. The programme keeps that record for every unit instead of leaving it to be assembled by hand.
Owners with oil or DGA results of concern
A result that has moved calls for a second sample, a trend and a decision on treatment, in that order.
Owners weighing regeneration against an oil change
Units in which oxidation has left the oil acidic, dark or sludging. Regenerating the oil keeps it in service; changing it brings in new oil. The results, read against IEC 60422, decide which.
Units in hot, humid or heavily cycled service
Heat, humidity, heavy loading and daily cycling age oil faster, and a schedule catches the change while it is still small.
Sites and networks with many units
Utilities and industrial sites that want one record of oil condition across every transformer, kept to the same methods from year to year.
Sites where fire safety or the environment argue for ester
Transformers indoors, close to people or in sensitive surroundings, where the owner wants a fluid that is harder to ignite and more readily biodegradable than mineral oil, in the unit already installed.
What an oil management programme includes
Scheduled sampling
A sampling schedule for each unit, set from its condition and duty. Samples for dissolved gas analysis follow IEC 60567; samples for the other tests follow IEC 60475.
Oil testing to published methods
The routine tests for each unit, chosen from the published oil-test schedule, with the method recorded beside every result.
Trending and alarm thresholds
Each result is added to the unit's trend and compared with alarm thresholds set per IEC 60422, so that a change shows before it crosses a limit.
On-site filtration, dehydration and degassing
Reconditioning with the transformer in place: filtration and vacuum treatment take particles, water and dissolved gases out of the oil, as IEC 60422 describes for oil in equipment.
Oil regeneration with Fuller's earth
Regeneration, also called reclamation, circulates the oil through Fuller's earth, which adsorbs the acids, sludge and other polar ageing products that oxidation leaves and reconditioning cannot remove. Acidity, interfacial tension, colour and dissipation factor move back towards the IEC 60422 limits for oil in service. The work is carried out on site, with the oil kept in the unit.
Full oil change
Where treatment will not recover the oil, it is drained and replaced with new mineral oil to IEC 60296.
Retrofill to natural or synthetic ester
The mineral oil drained and the unit refilled with a natural or synthetic ester, where fire safety or environmental compliance calls for a fluid that is harder to ignite and more readily biodegradable. Whether a unit suits a retrofill, and what it needs first, is settled from its design data and condition before the work is planned.
Used-oil handling and disposal
Spill containment and bunding wherever oil is handled on site, and used oil removed under a documented chain of custody.
How an oil management programme runs
A cycle rather than a single visit. Each pass through it adds a result to every unit's trend.
Sampling schedule
An interval set for each unit from its condition, duty and history.
Analysis
Each sample tested to the methods the programme sets for that unit.
Trending
Results compared with the unit's earlier values and with IEC 60422 thresholds.
Treatment when the trend calls for it
A treatment campaign planned with you when a threshold is crossed or a trend points towards one.
Verification
The oil re-tested after treatment, and the result added to the trend.
Used oil out
Any oil removed leaves site under a documented chain of custody.
What you provide
The assets and the site
The organisation, the site, the number of transformers with their rating and voltage ranges, the situation and your timeline: what the enquiry form asks for.
Existing records
DGA results, oil analysis and test reports, sent as a reply to our acknowledgement. A result means more when it is read against the same unit's history.
Outage windows
When each unit can be switched off, whether a regulated outage plan or a load-shedding rota sets it. Tests and work that need a de-energised unit are planned into those windows.
Access to the site
Access, ground conditions, crane availability and supply, confirmed at the site survey before a price is fixed.
What the programme gives you
A trended record for every unit
Each result with its method and its place in the unit's trend, read against IEC 60422 thresholds.
Treatment records
What was done to the oil and when, with the results before and after.
Chain-of-custody documentation
Paperwork that follows used oil from the site to a licensed disposal route.
Standards behind oil sampling, testing and treatment
Sampling, testing, interpretation and treatment each follow a published standard. The full oil-test schedule, with what each test tells you, is on the capabilities page.
| Standard | What it governs here |
|---|---|
| IEC 60422 | Supervision and maintenance of oil in service: alarm thresholds, reconditioning and replacement |
| IEEE C57.106 | Oil acceptance and maintenance where the specification is written to IEEE |
| IEC 60475 | Sampling for the general oil tests |
| IEC 60567 | Sampling for dissolved gas analysis, and the analysis itself |
| IEC 60599 | Interpreting dissolved gas results |
| IEC 60156 | Breakdown voltage |
| IEC 60814 | Water content |
| IEC 62021-1 | Acidity |
| IEC 60247 | Dissipation factor and resistivity |
| ASTM D971 | Interfacial tension |
| IEC 62535 | Potentially corrosive sulphur |
| IEC 60666 | Oxidation inhibitor content |
| IEC 60296 | New mineral oil for a full oil change |
The detail on the capabilities page
Transformer oil management: common questions
What is the difference between reconditioning and regenerating transformer oil?
Reconditioning removes water, dissolved gases and particles by filtration and vacuum treatment, with the transformer in place. It restores breakdown voltage and dryness, but leaves the acids, sludge and other polar products that oxidation creates. Regeneration runs the oil through an adsorbent such as Fuller's earth, which removes those ageing products too, and brings acidity, interfacial tension and colour back towards the IEC 60422 limits. Which one the oil needs is read from those results.
Should transformer oil be regenerated or replaced?
It depends on the condition of the oil and on what else is planned for the unit. Regeneration removes acids and sludge and keeps the oil in the transformer; a change drains it for new mineral oil meeting IEC 60296. Either way, sludge already settled on the windings and cooling surfaces has to be dealt with, and any oil removed leaves under a documented chain of custody. Neither route restores paper insulation that has already lost its strength, and the oil results, read against IEC 60422, decide between them.
How often should transformer oil be sampled?
There is no single interval. IEC baselines are the starting point, and conditions change them: heat, humidity, heavy loading and frequent cycling move moisture and acidity faster, so units working under them justify shorter intervals. In a programme the interval is set per unit from its condition and trend, and shortened when a result starts to move.
What does trending show that a single oil test does not?
A single result shows where the oil is today. A series shows how fast it is moving and in which direction. A water content that is still acceptable but rising with every sample, or an acidity climbing towards its limit, calls for action before either crosses it. That is why the programme is built on scheduled sampling rather than one-off tests.
Which tests does routine oil analysis include?
The published schedule includes dissolved gas analysis to IEC 60567, interpreted to IEC 60599; breakdown voltage to IEC 60156; water content to IEC 60814; acidity to IEC 62021-1; dissipation factor to IEC 60247; interfacial tension to ASTM D971; corrosive sulphur to IEC 62535; and oxidation inhibitor content to IEC 60666. Which of these each unit's routine sample receives is set in the programme.
What happens to used oil?
Used oil is removed under a documented chain of custody and disposed of through licensed facilities, with spill containment and bunding wherever oil is handled on site. Where the age or origin of the oil makes PCB contamination possible, it is screened, and contaminated oil is handled separately. The paperwork travels with the oil, so the disposal can be audited afterwards.
Scope this programme for your site
Tell us the assets, the site and the situation. The enquiry form opens with this programme already selected.