IEC TR 62617 pdf download – Home laundry appliances – Uncertainty reporting of measurements

IEC TR 62617 pdf download – Home laundry appliances – Uncertainty reporting of measurements
This Technical Report (TR) applies to uncertainty reporting of home laundry electricalappliances.
lt allows to estimate the uncertainty of a measured result and to predict the range of valuesthat may be measured when the same appliance is measured in another laboratory followingthe same measurement method.
NOTE The provisions in this TR can also be used to evaluate other kinds of products.
2Normative references
The following referenced documents are indispensable for the application of this document.For dated references, only the edition cited applies. For undated references, the latest editionof the referenced document (including any amendments) applies.
ISO/IEC Guide 98-3:2008,Uncertainty of measurement – Part 3: Guide to the expression ofuncertainty in measurement (GUM:1995)
IEC 61923:1997,Household electrical appliances – Method of measuring performance -Assessment of repeatability and reproducibility
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.
3.1
repeatability conditions
conditions where independent test results are obtained with the same method on identical testitems in the same laboratory by the same operator using the same equipment within shortintervals of time
[IEC 61923:1997,3.6]
3.2
repeatability standard deviation
standard deviation of test results obtained under repeatability conditions[IEC 61923:1997,3.7]
3.3
reproducibility conditions
conditions were test results are obtained with the same method on identical test items indifferent laboratories with different operators using different equipment
[IEC 61923:1997,3.9]
3.4
reproducibility standard deviation
standard deviation of test results obtained under reproducibility conditions
[EC 61923:1997,3.10]
3.5
statistical uncertainty
repeatability standard deviation obtained in one laboratory under repeatability conditions
3.6
expanded uncertainty
confidence interval,which allows to calculate the minimum and maximum value where theaverage measured result may be found when the measurement is re-done at any otherlaboratory following reproducibility conditions
4The approach to uncertainty measurement
4.1 The importance of the uncertainty
When a measurement has been performed giving a figure as a result for some quantity (i.e.the measurand), how sure is this figure? In other words:
– if the measurement is repeated,will the same figure be achieved as the result?
– if another group or another laboratory performs the measurement，how close will the
results expected to be?
By means of an uncertainty amount an uncertainty interval y ± U may be calculated,where yis the measurement result and U the expanded uncertainty that is determined to give theinterval a high probability (often 95 %) to cover the true value，Y, of the measurand.u is saidto be the uncertainty associated with the result y.
The uncertainty interval of a measurement is therefore a basis for qualifying themeasurement.The more narrow the confidence interval is desired, i.e. the smaller the valueof the uncertainty U is pursued， the more careful the measurement method, the measuringequipment, the training of the operators and the number of repetitions of the same experimenthave to be.
4.2ways to access uncertainty
There are in principle two ways to estimate uncertainty: a bottom up method and a top downmethod.The two methods should often be used in parallel to achieve a reliable uncertaintyamount.
a) The bottom up method (Refer to Clause 2,Guide to the Expression of Uncertainty in
Measurementy
ln this method the test result y is expressed as a function of input quantities. This function isoften the formula used for the calculation of the result.
ln the case of home laundry appliances, the y may be one of the final test results like waterconsumption，energy consumption, washing performance，spin speed,spin dryingperformance, program duration or rinsing efficiency.The input quantities may be temperature,masses, times，power etc.
The magnitude of all the uncertainty contributions of each input quantity is estimated.
By combining the uncertainties of the input quantities according to the law of propagation of uncertainty (see Clause 2, Guide to the Expression of Uncertainty in Measurement) the uncertainty of the result y can be calculated.