Feasibility study of accredited testing and calibration laboratories at Polytechnic University of Turin in Tashkent (TTPU)

The main purpose of the thesis is to study the feasibility of calibration and testing laboratories, which will be established at Polytechnic University of Turin in Tashkent (TTPU). Nowadays in Uzbekistan there is a primary laboratory, Uzbek National Institute of Metrology (OZ MMi), and the Uzbek Centre of Accreditation (O¿ZAKK, a full member of ILAC), but there are not yet any accredited secondary laboratories. In March 2023 several meetings with OZ MMi and O¿ZAKK were held at TTPU, traceability issues have been discussed, the reference standards have been selected and the instrumentation for the laboratory was defined. As regards the testing laboratory, several Uzbek companies want to export their products in Europe and to achieve this goal such products must be first tested according to the European standards. During the 2023 spring, the companies consortium Eltek provided a list of products to be exported in Europe, which mainly consists of household appliances and conductive wires. For this reason, the international standards CEI EN 60335-1 for the safety of household and similar electrical appliances and CEI EN 60851-5 for winding wires have been considered. To select the suitable equipment, mechanical, electrical and thermal tests have been investigated, with the main focus on electrical tests. Such tests include electromagnetic compatibility (EMC), leakage current, electric strength and power measurements. When it concerns measurements, the corresponding uncertainty is not always specified, thus requiring uncertainty to be set according to the given tolerance. Then, instruments with suitable specifications, such as multimeters and wattmeters, have been selected considering the risk of a wrong decision. A probabilistic approach has been adopted evaluating the Probability of False Acceptance. On the other hand, the EMC tests require a more complex instrumentation: an electrostatic discharge test table with coupling planes and grounding cables and an anechoic chamber equipped with antennas and spectrum analysers. For mechanical tests, the required items are mainly torque meters, strain gauges and load cells. About climatic tests, such as resistance against moisture, the tools needed are spray nozzle, oscillating tube and drip box, while for the hygroscopic treatments a thermal cycle test chamber is needed, in addition to thermocouples and stoves. Another important issue has also been considered, since some of the test equipment can be calibrated at the TTPU calibration laboratory. A methodology has been defined to select the instruments that can act as reference standards for the devices under calibration. Such a methodology has been implemented for a case study, which is the leakage current test. A commercial device has been identified (Associated Research 620L) and from its uncertainty the suitable reference standards have been selected, using a criterion based on the Test Uncertainty Ratio. The devices selected for the calibration laboratory are: digital multimeter (Fluke 8588A), multi-product calibrator with oscilloscope calibration option (Fluke 5550A), cable kits, thermo-hygrometer (Fluke 1621-S-256). For both laboratories it is also necessary to install a proper air-conditioning system and constantly monitor temperature and humidity conditions. After selecting the complete instrumentation, the required budget is about 100 keuro for the calibration laboratory, 20 keuro (mechanical tests), 50 keuro (electrical tests), and 400 keuro (EMC tests) for the testing laboratory.