Gaber Begeš

Calculation and proper presentation of the measurement uncertainty in testing

This paper deals with metrology elements, such as measurement uncertainty and traceability in testing laboratories. Newly implemented standard ISO/IEC 17025 is taken into consideration. The paper is focused at uncertainty analysis of test procedures on examples as useful case studies. It describes uncertainty propagation and proper decision of conformance or non-conformance with specifications. The knowledge and awareness regarding all facts about measuring, traceability, measurement uncertainty, calibration and testing requirements, is essential in order to make the right conclusion on safety of products.

Data acquisition module with large number of inputs

This paper presents data acquisition module with large number of inputs. The module was developed for data acquisition of thermocouples, but it can be used also for other applications. The aim of this paper is to depict the need for designing a new data acquisition module, an improved custom made version with a large number of inputs. This paper describes the process of developing the new data acquisition module and its possible use for different purposes. What is also presented here is an example of use in a measurement system that is one of many safety tests performed on electrical appliances. With the newly developed design many more sensor inputs can be available for less cost in comparison to the solution of adding new data acquisition modules in a computer.

Testing of heating in a black test corner

The article describes implementation of a personal computer and the LabVIEW program in measurement of temperature rise in a black corner in testing laboratories, which find the safety of household and similar appliances. A testing device can be considered as a complete measurement system, which can be regularly calibrated and thus provide traceable measurements. Besides the automation of the measuring process traceability is the most important category that must be considered in accredited laboratories. The whole project with its extension could change the heating part of the standard or more likely cause an edition of a new standard describing the testing in the black corner.

Information Extraction from Interlaboratory Comparison in Testing—Temperature Measurement in the Black Test Corner

This paper presents extraction of information from results of an interlaboratory comparison in testing, which was performed in the scope of the 5th Framework Program—INCOLAB (INitiative and CO-ordination to prepare LABoratories in Newly Associated States for full implementation of the (LVD) Low-Voltage Directive) project. The comparison covers all the requirements of classical proficiency testing, but also adds metrological aspects in order to improve the outcome of such tests, which is new in the field of interlaboratory comparisons in testing of electric safety. The objective was to show differences in methods and measurements in the black test corner (BTC, which is one of the tests required by the LVD directive standards), when performing the conformity assessment. A digital convection oven and a cooker were chosen as representative samples for comparison. Different shapes of samples were used to put forward understanding and application of the standard requirements. Additionally, the temperature artifact was used for comparison of the BTCs of different participating laboratories. All participating laboratories in this intercomparison were requested to follow the basic instructions given in the technical protocol, applying their everyday test procedure. Results showed a few problematic areas in safety testing. The entire intercomparison proved that in general, and for LVD in particular, better specification for BTCs as an example for a complex measuring instrument is required. Additional information about test samples was also obtained. The concern arising is that a product can be placed on the EU market with the conformity assessment activity support of testing laboratories with quite different measurement capabilities.

On-Site Environmental Conditions—Do They Really Affect the Measuring Accuracy?

According to requirements of the ISO/IEC 17025:2005 standard, environmental conditions while calibrating are monitored and stated in the calibration certificate. In this paper we present an experiment for evaluation of the behavior of our on-site measuring equipment regarding its specifications and the suitability of these specifications for our typical on-site work. We built a measuring setup for determining the temperature and relative humidity dependence of our on-site equipment. Main units of the equipment were placed in a climatic chamber, while temperature sensors and humidity sensors were placed into an ice bath and humidity generator, respectively. The temperature and relative humidity conditions in the climatic chamber were changed incrementally from 5°C to 45° and from 80 % to 20 %. Results are presented and evaluated. The built measuring setup was proven to be a useful tool for determining the temperature and relative humidity dependence of our on-site equipment. By observing the dynamic transitions of the instrumentation between changes of conditions possible dynamic effects could be evaluated also.

Automation of glow-wire test apparatus

The object of this paper is to present a low-cost automation of the glow-wire test apparatus. Glow-wire test apparatus is used for fire hazard testing of household and similar electrical appliances. In the original configuration, the carriage which supports the test specimen has to be manually moved to the glow-wire. In the improved system, a microcontroller is used in conjunction with a stepper motor and optical distance sensor to fully automate the carriage movement. The result is a better objectivity and reduced health hazard for the person performing the test. Sources of uncertainty are also evaluated.