Test services
Five test disciplines inside one accredited quality system. Every enquiry is answered with a test plan that states the standard, the sample requirement, the price and — where it matters — whether the item falls inside the accredited scope.
The laboratory was accredited in 2015 and renewed under certificate CNAS L7721 effective 27 May 2024, valid to 26 May 2030. The accredited scope covers about 200 test items across roughly 80 national standards; test work outside that scope is carried out under the same quality system but is identified separately in the report.
Electrical testing
High-voltage and high-current testing on power cables, fittings, cable accessories, insulators and arresters, and on HV/LV electrical products — pole-mounted vacuum circuit breakers, disconnectors, load-break switches, HV fuses and low-voltage switchgear assemblies. Tests are performed to the standard named in your specification and reported clause by clause, so the report can be read against the standard directly.
- Power-frequency withstand voltage testing
- Lightning impulse and short-time voltage impulse
- Partial discharge measurement
- DC resistance of conductors and connections
- Temperature rise and thermal cycling
- Conductor resistance, insulation thickness and AC withstand voltage on LV and MV power cables
- Flame propagation and ageing on wires and cables
- Power characteristics and over-current testing
- Withstand voltage, temperature rise and mechanical operation on HV switchgear and LV assemblies
Principal equipment
| Withstand voltage test set | 50 kW / 150 kV |
| Short-time voltage impulse | 20 kV |
| Temperature rise & thermal cycling | 4,000 A |
| Partial discharge detector | pC measurement |
| Over-current test instrument | Switchgear assemblies |
| DC resistance measurement | Micro-ohm range |
Applied to: power cables, power fittings, cable accessories, insulators, surge arresters, pole-mounted vacuum circuit breakers (10 & 35 kV), disconnectors, load-break switches, HV fuses and LV switchgear assemblies.
Mechanical testing
Load, fatigue and forming tests on line hardware and cable accessories. Load is applied to the value defined in the standard, and the failure mode is photographed and described — because on a claim, how a fitting failed matters as much as the number it reached.
- Failing load and specified load tests on clamps and connectors
- Slip load and grip strength of tension assemblies
- Tensile strength and elongation of conductors and profiles
- Fatigue testing under repeated load cycles
- Bending, impact and hardness testing
- Component inspection after test, with photographs
Principal equipment
| Electro-hydraulic servo universal testing machine | MTS, 600 kN |
| Horizontal tensile testing machine | 600 kN, servo-hydraulic |
| Loading frames for fittings assemblies | Failing load & slip load |
| Hardness testing | Metallic materials |
The horizontal machine was chosen for long assemblies — tension strings, jumper assemblies and tube busbar that cannot be mounted vertically.
Material analysis
Composition, microstructure and coating. This is the discipline that answers the awkward questions — whether the aluminium is the grade stated on the drawing, whether the galvanising is thick enough, and why a part cracked in service.
- Chemical composition of aluminium, copper and steel by optical emission spectrometry
- Alloy grade verification on incoming material with handheld XRF
- Microstructure and grain structure examination under a metallurgical microscope
- High-magnification imaging and element mapping by scanning electron microscopy
- Zinc coating mass by gravimetric method, adhesion and thickness
- Fracture surface examination as part of failure analysis
Principal equipment
| Scanning electron microscope | Thermo Fisher |
| Optical emission spectrometer | SPECTROMAXx |
| Metallurgical microscope | ZEISS |
| Handheld XRF analyser | Olympus |
Material testing is the oldest capability in the laboratory; the group has produced aluminium and copper transmission hardware since 1985.
Ageing & environmental testing
Accelerated ageing to predict service life in hot, humid and high-UV conditions — the climates where most of China's transmission equipment is installed overseas. Ageing is usually run before a mechanical or electrical re-test, so the sample is compared against its own baseline.
- Heat ageing in controlled circulating-air ovens
- Xenon-arc ageing for UV resistance of polymers and coatings
- Thermal cycling between defined temperature limits
- Ageing followed by tensile, load or electrical re-test
Why this matters for export
A fitting that passes its failing load test in a laboratory at 20 °C has not answered the question a buyer in West Africa or the Middle East is asking. Ageing programmes are usually written into the purchase order for exactly that reason, and the report has to show the cycle that was applied.
The standard cycle, duration and acceptance limits are confirmed at the test plan stage, because they differ between IEC, GB and customer specifications.
Non-destructive testing & failure analysis
Detection of internal defects without cutting the part, and investigation of parts that have already failed. Applied mostly to castings, welded assemblies, cable accessories and crimped connections.
- X-ray digital radiography of castings, welds and assemblies
- Dye penetrant and magnetic particle inspection
- Ultrasonic inspection of wall thickness and internal defects
- Root-cause analysis of a failure, from fracture surface to process step
- Technical report suitable for commercial negotiation or an insurance claim
Principal equipment
| X-ray digital radiography system | Varian |
| Ultrasonic flaw detector | Wall thickness & defects |
| Penetrant & magnetic particle | Surface defects |
Where a defect is confirmed, metallography and SEM imaging are used together to identify whether the cause is material, tooling, process or handling.
Before you send a sample
It depends on the test. As a rough guide: 5–10 m for LV cable, 10–15 m for an MV cable type test, 2–3 pieces for a mechanical fittings test, one unit for a switchgear or arrester type test. The test plan states the exact quantity — do not ship before it is confirmed.
Often, yes. EN, ASTM, IS and utility specifications are common requests. Send the full text of the method, because the differences are frequently in the conditioning and the acceptance criteria rather than the measurement itself. If a method falls outside the accredited scope, we will say so before you order.
CNAS is a signatory to the ILAC Mutual Recognition Arrangement and the APAC MRA. Reports covering items inside the accredited scope carry the accreditation mark and are accepted by accreditation bodies and regulators in the economies that are party to those arrangements. Whether a specific buyer accepts a particular report always remains the buyer's decision — if they have a written specification, send it and we will check the report against it.
You receive the measured values, the requirement limit and a non-conforming conclusion. We do not withhold a result, and we do not amend a report to change one. A retest may be requested on a new sample, and the correlation between the two reports is stated. See the amendment and retest policy on the client service page.
Witness testing at your works and sample collection can be arranged for projects in Zhejiang, Jiangsu and Sichuan, and elsewhere by agreement. Note that witness attendance is not part of the accredited scope, and the resulting document is issued as a test report on the samples tested, not as an inspection certificate.
Per test item, with the standard and the sample preparation stated separately. A test plan quoting each item is issued before work starts, so the invoice matches what was agreed. Volume rates are available where a batch of identical assemblies is submitted.
Send the standard, get a test plan
Product drawing, the standard quoted by the buyer and your deadline is all we need to start.