Trusted Transformer Oil Testing in South Africa

We are wholly independent. We are not owned by, nor commercially linked to, any oil supplier, transformer OEM, refurbisher or service provider — so the results we deliver carry no commercial bias.

Yes. We routinely receive and test samples couriered in from outside South Africa. Get in touch with sample volumes, voltage class and origin and we'll advise on the best sampling kit and courier route.

Yes. Clients receive online access to their report archive — historical results, trend graphs and downloadable PDFs — alongside email delivery of each new report.

Our laboratory is located at Unit 2A, Protea Industrial Park, 7 Protea Street, Aureus, Randfontein, Gauteng, South Africa. We serve clients across South Africa and the broader African continent.

Transformer oil is both an insulator and a coolant. Once it absorbs moisture, oxidises, or starts breaking down from internal faults, the transformer is on borrowed time. Routine oil testing tells you the condition of the oil and gives early warning of faults inside the tank (overheating, partial discharge, arcing) — usually months before a trip or failure. On a mine, where an unplanned transformer failure can stop a shaft, mill or section, oil testing is the cheapest insurance you can buy.

We test to the standards a mining EE or COP will expect to see on the report:

• SANS 60422 / IEC 60422 — in-service mineral oil maintenance and condition limits
• IEC 60156 — breakdown voltage (BDV)
• IEC 60814 — moisture content (Karl Fischer, ppm water)
• IEC 60567 / ASTM D3612 — dissolved gas analysis (DGA) sampling and testing
• IEC 60599 — interpretation of DGA results (Duval triangles, key gas, ratios)
• IEC 62535 / IEC 61619 — corrosive sulphur and PCB screening

The report references the exact clause used, so it stands up in an audit.

A practical mining schedule that aligns with SANS 60422:

• Critical / large units (≥ 5 MVA, shaft winders, mill drives, main intake transformers): DGA every 6 months, full oil quality (BDV, moisture, acidity, IFT, colour, DDF) annually.
• Standard distribution and section transformers: full oil quality annually, DGA at least annually or whenever a unit is suspect.
• New or recently repaired units: sample at commissioning, 3 months later, then fall into the routine cycle.
• After any electrical event (through-fault, lightning strike, protection operation, abnormal noise, gas relay alarm): sample immediately.

A bad sample gives a misleading report. The basics:

1. Use the bottom drain valve for routine oil quality samples — that is where moisture and sediment settle.
2. Use the dedicated DGA sampling point (or the bottom valve if none) and a glass syringe or sealed metal can for DGA. Plastic bottles let dissolved gases escape — the result is meaningless.
3. Flush 1–2 litres through the valve before filling the sample container, into a separate waste bottle.
4. Fill slowly to avoid creating bubbles. For DGA, exclude all air — no headspace.
5. Sample with the transformer in service if safe to do so (running temperature, oil circulating). If not, sample as soon after shut-down as practical.
6. Label immediately: site, transformer ID, serial number, MVA, voltage, top oil temperature, ambient, date, time, sampler's name.
7. Keep upright, out of direct sun, and courier within 48 hours.

We supply sample kits (bottle, syringe, labels, chain-of-custody form) on request. See our full transformer oil sampling guide.

• Routine oil quality (BDV, moisture, acidity, etc.): 1 litre in a clean amber glass bottle.
• DGA only: 50–100 ml in a glass syringe or sealed metal can.
• Full suite + furans + PCB: 1.5 litres.

Yes, provided the unit has a sampling valve designed for live sampling, the foreman has authorised it, the sampler is competent and wearing arc-rated PPE, and a second person is in attendance. If there is any doubt — gas relay alarm, recent fault, audible discharge, oil leaking — do not sample live. Isolate first.

Oil quality tells you the condition of the oil itself — is it still a good insulator and coolant. DGA tells you what is happening inside the transformer by measuring the gases dissolved in the oil. You want both. Oil quality answers "must I dry, filter or replace this oil?" DGA answers "is this transformer developing a fault?"

Limits tighten at higher voltages — the report flags your unit against the correct SANS 60422 voltage class. More on breakdown voltage testing.

Each gas points to a different kind of fault:

• Hydrogen (H₂) — partial discharge / corona
• Methane (CH₄), ethane (C₂H₆) — low-temperature thermal faults (< 300 °C)
• Ethylene (C₂H₄) — high-temperature thermal faults (> 700 °C, hot spots)
• Acetylene (C₂H₂) — arcing. Treat as serious. Any measurable C₂H₂ on a transformer that has never had one before warrants a follow-up sample.
• Carbon monoxide (CO), carbon dioxide (CO₂) — paper insulation degradation. Rising CO with rising furans = the windings are ageing.

The lab applies IEC 60599 ratios and the Duval triangle to classify the fault. The report says, in plain English, what kind of fault is most likely (e.g. "T2 — thermal fault 300–700 °C") and what to do next. More on dissolved gas analysis.

Furans (especially 2-FAL) come from the breakdown of the paper insulation on the windings. You can't replace paper without rewinding. Order a furan test when:

• the transformer is > 15 years old, or
• CO and CO₂ are climbing, or
• you're deciding whether to refurbish or replace.

More on furan testing.

Yes. Any oil topped up before the late 1980s, or of unknown history, should be screened. We do an L2000 / GC screen and issue a certificate suitable for waste disposal and DMRE compliance.

• Routine oil quality: 3–5 working days from receipt.
• DGA: 2–3 working days.
• Emergency / fault investigation: 24 hours, by arrangement, for a surcharge.

Couriers from remote sites add 1–2 days — factor that in.

PDF report by email, with raw data, comparison to SANS 60422 limits, trend graph against previous samples on the same unit, and a plain-language recommendation (continue service / re-sample / recondition / investigate / remove from service). Clients also have online access to their full report archive.

The oil itself is still serviceable but needs to be dried and filtered (typically by hot oil filtration / vacuum dehydration on site). The transformer doesn't have to be taken out of service for long. Reconditioning is far cheaper than an oil change.

This is reserved for cases where the oil and/or the gas pattern indicate the transformer is unsafe to keep running — for example, rising acetylene, BDV well below limit with confirmed moisture, or a sudden DGA shift. Isolate the unit, do not energise, and call us — we'll usually recommend an immediate re-sample to confirm, and an inspection by your transformer OEM or a qualified repairer.

Not necessarily — but it has to be taken seriously. Acetylene means arcing somewhere in the tank. Steps:

1. Re-sample within 24–48 hours to confirm and check the trend.
2. Reduce load if possible.
3. Check Buchholz / gas relay; do not reset without sampling the gas.
4. If acetylene is rising sample-to-sample, plan an outage.

What matters is the rate of change, not a single number. A unit with 25 ppm H₂ that has been sitting at 25 ppm for five years is far less concerning than one that went from 5 to 25 ppm in three months. The report shows trend graphs for exactly this reason — keep the historical samples on file and always send the previous report number with new samples so we can plot it for you.

Yes. We run scheduled site visits across Gauteng and to mines on request elsewhere in South Africa and the region. For a fleet of more than ten transformers, an on-site sampling and condition-monitoring contract usually works out cheaper than crew time + courier + sample kits.