IEC IEEE 62582-4 pdf download

IEC IEEE 62582-4 pdf download.Nuclear power plants – Instrumentation and control important to safety – Electrical equipment condition monitoring methods
1 Scope and object
This part of IEC/IEEE 62582 specifies methods for condition monitoring of organic and polymeric materials in instrumentation and control systems using oxidation induction techniques in the detail necessary to produce accurate and reproducible measurements. It includes the requirements for sample preparation, the measurement system and conditions, and the reporting of the measurement results. The different parts of IEC/IEEE 62582 are measurement standards, primarily for use in the management of ageing in initial qualification and after installation. Part 1 of IEC/IEEE 62582 includes requirements for the application of the other parts of IEC/IEEE 62582 and some elements which are common to all methods. Information on the role of condition monitoring in the qualification of equipment important to safety is found in IEEE Std 323.
2 Terms and definitions
For the purposes of this standard, the following terms and definitions apply. 2.1 Oxidation Induction Time (OIT) relative measure of a stabilised material’s resistance to oxidative decomposition, determined by the calorimetric measurement of the time interval to the onset of exothermic oxidation of the material at a specified temperature in an oxygen atmosphere, under atmospheric pressure NOTE OIT is expressed in minutes (min). 2.2 Oxidation Induction Temperature (OITP) calorimetric measurement of the temperature of the onset of exothermic oxidation of the material when subjected to a specified heating rate in an oxygen atmosphere, under atmospheric pressure NOTE OITP is expressed in degrees Celsius (°C).
4 General description
Oxidation induction methods are based on the detection of the oxidation exotherm that occurs when a sample is heated in the presence of oxygen. This exotherm is sensitive to the level of degradation in some organic and polymeric materials and can be used as an indicator of ageing. There are two oxidation induction methods available, based on the time required to reach the onset of oxidation at a constant temperature (oxidation induction time – OIT) or based on the temperature at the onset of oxidation during a constant temperature ramp rate (oxidation induction temperature – OITP). The two methods are complementary, in that OITP is often effective in those materials where OIT is difficult to determine. OIT and OITP decrease with increasing degradation. The methods are related to the amount of antioxidants present in the material. As degradation proceeds, these antioxidants are depleted.
5 Applicability and reproducibility
The oxidation induction method is primarily suited to samples taken from materials (such as cable jackets or insulation) that are polyolefin-based (e.g. polyethylene PE, cross-linked polyethylene XLPE). It can also be used for some materials based on ethylene-propylene polymers (e.g. ethylene propylene rubber EPR, ethylene propylene diene EPDM) and for some ethylene vinyl acetate EVA materials. It is not applicable to high temperature polymers, such as poly ether ether ketone (PEEK). The method is generally not suitable for chlorinated polymers (e.g. polyvinyl chloride PVC, chlorosulphonated polyethylene CSPE) because of the corrosive degradation products evolved during the measurements, which can damage the instrument. For these materials, smaller sample masses (1 mg to 2 mg) may enable the method to be used with care. The method is not suitable for field use in the nuclear power plant but uses samples taken from the plant, which are then measured in the laboratory. Each OIT measurement in the laboratory can take up to 90 min to complete for unaged samples, decreasing for heavily aged samples, whereas OITP measurements typically take 30 min to 40 min. Measurements of OIT typically have a standard deviation of 5 % to 1 0 % of the mean value whereas measurements of OITP typically have a standard deviation of 1 % to 3 % of the mean value, both within the same laboratory and between different laboratories. Some of this variation arises from inhomogeneity of the sample materials, which becomes significant when making condition measurements on samples whose mass is very low. OITP measurements are usually more reproducible than OIT measurements but require baseline data for interpretation of the changes.