{"id":54414,"date":"2021-07-26T17:37:01","date_gmt":"2021-07-26T15:37:01","guid":{"rendered":"https:\/\/www.reersafety.cn\/safety-guide\/iso-13849-12safety-of-machinery\/simplified-method-for-estimating-the-quantifiable-part-of-the-pl\/"},"modified":"2022-05-06T15:45:58","modified_gmt":"2022-05-06T13:45:58","slug":"simplified-method-for-estimating-the-quantifiable-part-of-the-pl","status":"publish","type":"page","link":"https:\/\/www.reersafety.cn\/zh-hans\/academy\/safety-guide\/iso-13849-12safety-of-machinery\/simplified-method-for-estimating-the-quantifiable-part-of-the-pl\/","title":{"rendered":"Simplified method for estimating the quantifiable part of the PL"},"content":{"rendered":"\n<div class=\"row\"  id=\"row-263261354\">\n\n\n\t<div id=\"col-1957345892\" class=\"col small-12 large-12\"  >\n\t\t<div class=\"col-inner\"  >\n\t\t\t\n\t\t\t\n\n  <div id=\"page-header-1076023719\" class=\"page-header-wrapper\">\n  <div class=\"page-title light simple-title\">\n\n    \n    <div class=\"page-title-inner container align-center flex-row medium-flex-wrap row-reverse\" >\n            <div class=\"title-content flex-col flex-left text-left medium-text-center\">\n        <div class=\"title-breadcrumbs pb-half pt-half\"><nav class=\"woocommerce-breadcrumb breadcrumbs uppercase\">\u9996\u9875<\/nav><\/div>      <\/div>\n    <\/div>\n\n       <\/div>\n    <\/div>\n  \n\n\n\t\t<\/div>\n\t\t\t<\/div>\n\n\t\n\n<\/div>\n<div class=\"row\"  id=\"row-976379560\">\n\n\n\t<div id=\"col-1291969429\" class=\"col small-12 large-12\"  >\n\t\t<div class=\"col-inner\"  >\n\t\t\t\n\t\t\t\n\n<div class=\"row\"  id=\"row-109702431\">\n\n\n\t<div id=\"col-427756654\" class=\"col small-12 large-12\"  >\n\t\t<div class=\"col-inner text-left\"  >\n\t\t\t\n\t\t\t\n\n\t<div id=\"text-1397924960\" class=\"text cutom-ul\">\n\t\t\n\n<h2>Simplified method for estimating the quantifiable part of the PL<\/h2>\n<p>After having chosen the category, verified that CCF scoring has been respected (for redundant architectures), found MTTF<sub>D<\/sub>, and DC values, the PL and the PFHD can be derived directly from table K.1 of the Standard.<\/p>\n<p>The values of table K.1 have been computed by applying Markov analisys to the designated architectures of the 5 categories. Therefore, if the simplified method of the Standard is used, it is not possible to make exceptions regarding the Categories. The values of table K.1 have been calculated assuming that:<\/p>\n<ul>\n<li>Mission time = 20 years<\/li>\n<li>Constant failure rate throughout the mission time<\/li>\n<li>For Category 2: The test frequency is at least 100 times higher than the request frequency of the safety function and the MTTF<sub>D<\/sub> of the test channel is greater than half the MTTF<sub>D<\/sub> of the functional channel<\/li>\n<\/ul>\n<p>Table K.1 is read as follows:<\/p>\n<p>The calculated MTTF<sub>D<\/sub> value is identified in a row of the left column and, after identifying the column corresponding to the implemented Category and the calculated DC, the PL and the PFH<sub>D<\/sub> value are found.<\/p>\n\t\t\t<\/div>\n\t\n\t<div class=\"img has-hover x md-x lg-x y md-y lg-y\" id=\"image_756902687\">\n\t\t\t\t\t\t\t\t<div class=\"img-inner dark\" style=\"margin:0px 0px 0px 100px;\">\n\t\t\t<img width=\"1020\" height=\"537\" src=\"https:\/\/www.reersafety.cn\/wp-content\/uploads\/2021\/07\/EN_Tabel-K1_sample-1024x539.png\" class=\"attachment-large size-large\" alt=\"\" decoding=\"async\" loading=\"lazy\" srcset=\"https:\/\/www.reersafety.cn\/wp-content\/uploads\/2021\/07\/EN_Tabel-K1_sample-1024x539.png 1024w, https:\/\/www.reersafety.cn\/wp-content\/uploads\/2021\/07\/EN_Tabel-K1_sample-300x158.png 300w, https:\/\/www.reersafety.cn\/wp-content\/uploads\/2021\/07\/EN_Tabel-K1_sample-768x404.png 768w, https:\/\/www.reersafety.cn\/wp-content\/uploads\/2021\/07\/EN_Tabel-K1_sample-510x268.png 510w, https:\/\/www.reersafety.cn\/wp-content\/uploads\/2021\/07\/EN_Tabel-K1_sample.png 1028w\" sizes=\"(max-width: 1020px) 100vw, 1020px\" \/>\t\t\t\t\t\t\n\t\t\t\t\t<\/div>\n\t\t\t\t\t\t\t\t\n<style>\n#image_756902687 {\n  width: 100%;\n}\n<\/style>\n\t<\/div>\n\t\n\n<p>If it is needed only the PL value, then the graph of figure 5 of the standard can be used.<\/p>\n<p>The combination of category and DC identifies one of the seven columns; the calculated MTTFD range determines which part of the column to consider. The corresponding PL value can then be read directly on the left side of the graph<\/p>\n\t<div class=\"img has-hover x md-x lg-x y md-y lg-y\" id=\"image_928858896\">\n\t\t\t\t\t\t\t\t<div class=\"img-inner dark\" style=\"margin:0px 0px 0px 200px;\">\n\t\t\t<img width=\"800\" height=\"430\" src=\"https:\/\/www.reersafety.cn\/wp-content\/uploads\/2021\/07\/EN_ISO-13849_fig_5-1.png\" class=\"attachment-original size-original\" alt=\"\" decoding=\"async\" loading=\"lazy\" srcset=\"https:\/\/www.reersafety.cn\/wp-content\/uploads\/2021\/07\/EN_ISO-13849_fig_5-1.png 800w, https:\/\/www.reersafety.cn\/wp-content\/uploads\/2021\/07\/EN_ISO-13849_fig_5-1-300x161.png 300w, https:\/\/www.reersafety.cn\/wp-content\/uploads\/2021\/07\/EN_ISO-13849_fig_5-1-768x413.png 768w, https:\/\/www.reersafety.cn\/wp-content\/uploads\/2021\/07\/EN_ISO-13849_fig_5-1-510x274.png 510w\" sizes=\"(max-width: 800px) 100vw, 800px\" \/>\t\t\t\t\t\t\n\t\t\t\t\t<\/div>\n\t\t\t\t\t\t\t\t\n<style>\n#image_928858896 {\n  width: 100%;\n}\n<\/style>\n\t<\/div>\n\t\n\n\t<div id=\"text-1742976285\" class=\"text cutom-ul\">\n\t\t\n\n<p>Fig. 12 &#8211; ISO 13849-1 &#8211; Figure 5<\/p>\n<p>It may happen that the part of the column chosen includes two or three possible PL values (e.g in the case of Cat. 3, DC = medium and MTTF<sub>D<\/sub> = low, the following three values are possible: PL b, PL c, PL d) in these cases, table K.1 is used to get the correct PL value. As can be seen from Figure 5 for each Performance Level specified are available different choices. As an example from Table 5*it can be seen that for a system having PL of \u201cc\u201d the following five alternatives are possible:<\/p>\n<ul>\n<li>Category 3 with MTTFD = Low and DC medium<\/li>\n<li>Category 3 with MTTFD = Medium and DC low<\/li>\n<li>Category 2 with MTTFD = Medium and DC medium<\/li>\n<li>Category 2 with MTTFD = High and DC low<\/li>\n<li>Category 1 with MTTFD = High<\/li>\n<\/ul>\n<h3>Estimation of the PL based only on the Category information<\/h3>\n<p>This method is applicable only to the output subsystem of an SRP\/CS. If for mechanical, hydraulic or pneumatic components (or components comprising a mixture of technologies) no application-specific reliability data are available, the machine manufacturer may evaluate the quantifiable aspects of the PL without any MTTF<sub>D<\/sub> calculation.<\/p>\n<p>For such cases, the safety-related performance level (PL) is assured by the Category and by the measures against CCF. The next table shows the relationship between achievable PL and Categories.<\/p>\n\t\t\t<\/div>\n\t\n<table style=\"border-collapse: collapse; width: 100%; height: 126px;\">\n<tbody>\n<tr style=\"height: 21px;\">\n<td style=\"width: 14.2857%; height: 21px;\">&nbsp;<\/td>\n<td style=\"width: 14.2857%; height: 21px;\">PFHd (1\/h)<\/td>\n<td style=\"width: 14.2857%; height: 21px;\">Cat. B<\/td>\n<td style=\"width: 14.2857%; height: 21px;\">Cat. 1<\/td>\n<td style=\"width: 14.2857%; height: 21px;\">Cat. 2<\/td>\n<td style=\"width: 14.2857%; height: 21px;\">Cat. 3<\/td>\n<td style=\"width: 14.2857%; height: 21px;\">Cat. 4<\/td>\n<\/tr>\n<tr style=\"height: 21px;\">\n<td style=\"width: 14.2857%; height: 21px;\">PL a<\/td>\n<td style=\"width: 14.2857%; height: 21px;\">2*10<sup>-5<\/sup><\/td>\n<td style=\"width: 14.2857%; height: 21px;\">*<\/td>\n<td style=\"width: 14.2857%; height: 21px;\">0<\/td>\n<td style=\"width: 14.2857%; height: 21px;\">0<\/td>\n<td style=\"width: 14.2857%; height: 21px;\">0<\/td>\n<td style=\"width: 14.2857%; height: 21px;\">0<\/td>\n<\/tr>\n<tr style=\"height: 21px;\">\n<td style=\"width: 14.2857%; height: 21px;\">PL b<\/td>\n<td style=\"width: 14.2857%; height: 21px;\">5*10<sup>-6<\/sup><\/td>\n<td style=\"width: 14.2857%; height: 21px;\">*<\/td>\n<td style=\"width: 14.2857%; height: 21px;\">0<\/td>\n<td style=\"width: 14.2857%; height: 21px;\">0<\/td>\n<td style=\"width: 14.2857%; height: 21px;\">0<\/td>\n<td style=\"width: 14.2857%; height: 21px;\">0<\/td>\n<\/tr>\n<tr style=\"height: 21px;\">\n<td style=\"width: 14.2857%; height: 21px;\">PL c<\/td>\n<td style=\"width: 14.2857%; height: 21px;\">1,7*10<sup>-6<\/sup><\/td>\n<td style=\"width: 14.2857%; height: 21px;\">&#8211;<\/td>\n<td style=\"width: 14.2857%; height: 21px;\">*2<\/td>\n<td style=\"width: 14.2857%; height: 21px;\">*1<\/td>\n<td style=\"width: 14.2857%; height: 21px;\">0<\/td>\n<td style=\"width: 14.2857%; height: 21px;\">0<\/td>\n<\/tr>\n<tr style=\"height: 21px;\">\n<td style=\"width: 14.2857%; height: 21px;\">PL d<\/td>\n<td style=\"width: 14.2857%; height: 21px;\">2,9*10<sup>-7<\/sup><\/td>\n<td style=\"width: 14.2857%; height: 21px;\">&#8211;<\/td>\n<td style=\"width: 14.2857%; height: 21px;\">&#8211;<\/td>\n<td style=\"width: 14.2857%; height: 21px;\">&#8211;<\/td>\n<td style=\"width: 14.2857%; height: 21px;\">*1<\/td>\n<td style=\"width: 14.2857%; height: 21px;\">0<\/td>\n<\/tr>\n<tr style=\"height: 21px;\">\n<td style=\"width: 14.2857%; height: 21px;\">PL e<\/td>\n<td style=\"width: 14.2857%; height: 21px;\">4,7*10<sup>-8<\/sup><\/td>\n<td style=\"width: 14.2857%; height: 21px;\">&#8211;<\/td>\n<td style=\"width: 14.2857%; height: 21px;\">&#8211;<\/td>\n<td style=\"width: 14.2857%; height: 21px;\">&#8211;<\/td>\n<td style=\"width: 14.2857%; height: 21px;\">&#8211;<\/td>\n<td style=\"width: 14.2857%; height: 21px;\">*1<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<table class=\" aligncenter alignleft\" style=\"width: 100%; border-collapse: collapse; border-style: hidden;\">\n<tbody>\n<tr style=\"border-style: hidden;\">\n<td style=\"width: 3.87524%; border-style: hidden; height: 27px;\">\n<p>*<\/p>\n<\/td>\n<td style=\"width: 96.1248%; border-style: hidden; height: 27px;\">\n<p>Applied category is recommended<\/p>\n<\/td>\n<\/tr>\n<tr style=\"border-style: hidden;\">\n<td style=\"width: 3.87524%; border-style: hidden; height: 21px;\">\n<p>0<\/p>\n<\/td>\n<td style=\"width: 96.1248%; border-style: hidden; height: 21px;\">\n<p>Applied category is optional<\/p>\n<\/td>\n<\/tr>\n<tr style=\"border-style: hidden;\">\n<td style=\"width: 3.87524%; border-style: hidden; height: 21px;\">&#8211;<\/td>\n<td style=\"width: 96.1248%; border-style: hidden; height: 21px;\">\n<p>Category is not allowed<\/p>\n<\/td>\n<\/tr>\n<tr style=\"border-style: hidden;\">\n<td style=\"width: 3.87524%; border-style: hidden; height: 21px;\">*1&nbsp;<\/td>\n<td style=\"width: 96.1248%; border-style: hidden; height: 21px;\">\n<p>Proven in use or well-tried (confirmed by the component manufacturer to be suitable for particular application) components and well-tried safety principles must be used<\/p>\n<\/td>\n<\/tr>\n<tr style=\"border-style: hidden;\">\n<td style=\"width: 3.87524%; border-style: hidden; height: 21px;\">*2<\/td>\n<td style=\"width: 96.1248%; border-style: hidden; height: 21px;\">\n<p>Well-tried components and well-tried safety principles must be used. For safety-related components that are not monitored in the <br \/>process, the T10<sub>D<\/sub> value can be determined based on proven in use data by the machine manufacturer.<\/p>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p>&nbsp;<\/p>\n<p>PLa and PLb can be achieved by using Category B; PLc can be achieved by using Category 1 or Category 2; PLd can be achieved by using Category 3; PLe can be achieved by using Category 4.<\/p>\n<p>Furthermore:<\/p>\n<ul>\n<li>If Category 1 is used to obtain a PLc, it is essential:\n<ul>\n<li>Determine, for the components involved in safety, the T<sub>10D<\/sub> value. This value can be determined on the basis of \u201cproven in use\u201d data provided by the machine manufacturer<\/li>\n<\/ul>\n<\/li>\n<li>If Category 2 is used:\n<ul>\n<li>Well tried safety principles and well tried components declared suitable by the component manufacturer for the particular application must be used<\/li>\n<li>MTTF<sub>D<\/sub> of the test channel must be at least 10 years<\/li>\n<li>DC&nbsp;must be low or medium<\/li>\n<li>Measures to control CCF must be in place<\/li>\n<\/ul>\n<\/li>\n<li>If Category 3 is used:\n<ul>\n<li>Well tried safety principles and well tried components must be used<\/li>\n<li>DC must be low or medium<\/li>\n<li>Measures to control CCF must be in place<\/li>\n<\/ul>\n<\/li>\n<li>If Category 4 is used::\n<ul>\n<li>Well tried safety principles and well tried components must be used<\/li>\n<li>DC must be high<\/li>\n<li>Measures to control CCF must be in place<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<p>Since formula E.1 of the standard cannot be used for the computation of the DC due to the unavailability of the MTTFD values, the DC must be derived simply as the arithmetic average of the individual DC values of the components of the output subsystem.<\/p>\n<p>Proof that the component is \u201cproven-in-use\u201d is based on the failure analysis of the component over a long period of time used in the same specific configuration and for that particular application. There must be documented evidence that the probability of dangerous systematic failure of that component in that specific application is low enough for the required PL value.<\/p>\n<p>The concept of a \u201cproven in use\u201d component is a concept of the IEC 61508 standard.<\/p>\n<h3>Combination of several SRC\/PS to achieve the overall PL<\/h3>\n<p>The safety-related function may include one or more SRP\/CSs, and several safety-related function may use the same SRP\/CSs.<\/p>\n<p>Where the safety-related function is made by a series connection of several SRP\/CSs, e.g safety light curtains, control logics, power output, and if the PFHd values of all SRP\/CSs are known, than the PHFD of the combined SRP\/CS is the sum of all PFH<sub>D<\/sub> values of the N individual SRP\/CSs.<\/p>\n<p>The standard proposes two methods; a detailed one if for the single SRP\/CS, in addition to the PL, also the PFH<sub>D<\/sub> is known and a simplified one if only the PL is available.<\/p>\n<div class=\"accordion\" rel=\"\">\n\n<div class=\"accordion-item\"><a href=\"#\" class=\"accordion-title plain\"><button class=\"toggle\"><i class=\"icon-angle-down\"><\/i><\/button><span>Detailed method<\/span><\/a><div class=\"accordion-inner\">\n\n<p>If the PFH<sub>D<\/sub> of the single subsystems are known, the total PFH<sub>D<\/sub> is equal to the sum of the PFH<sub>D<\/sub> values of each subsystems.<\/p>\n\t<div class=\"img has-hover x md-x lg-x y md-y lg-y\" id=\"image_1751340910\">\n\t\t\t\t\t\t\t\t<div class=\"img-inner dark\" >\n\t\t\t\t\t\t\t\t\t\n\t\t\t\t\t<\/div>\n\t\t\t\t\t\t\t\t\n<style>\n#image_1751340910 {\n  width: 100%;\n}\n<\/style>\n\t<\/div>\n\t\n\n\t<div class=\"img has-hover x md-x lg-x y md-y lg-y\" id=\"image_1293557019\">\n\t\t\t\t\t\t\t\t<div class=\"img-inner dark\" >\n\t\t\t<img width=\"1020\" height=\"166\" src=\"https:\/\/www.reersafety.cn\/wp-content\/uploads\/2022\/05\/EN_deatailed-method-1024x167.png\" class=\"attachment-large size-large\" alt=\"\" decoding=\"async\" loading=\"lazy\" srcset=\"https:\/\/www.reersafety.cn\/wp-content\/uploads\/2022\/05\/EN_deatailed-method-1024x167.png 1024w, https:\/\/www.reersafety.cn\/wp-content\/uploads\/2022\/05\/EN_deatailed-method-300x49.png 300w, https:\/\/www.reersafety.cn\/wp-content\/uploads\/2022\/05\/EN_deatailed-method-768x125.png 768w, https:\/\/www.reersafety.cn\/wp-content\/uploads\/2022\/05\/EN_deatailed-method-1536x251.png 1536w, https:\/\/www.reersafety.cn\/wp-content\/uploads\/2022\/05\/EN_deatailed-method-2048x335.png 2048w, https:\/\/www.reersafety.cn\/wp-content\/uploads\/2022\/05\/EN_deatailed-method-510x83.png 510w\" sizes=\"(max-width: 1020px) 100vw, 1020px\" \/>\t\t\t\t\t\t\n\t\t\t\t\t<\/div>\n\t\t\t\t\t\t\t\t\n<style>\n#image_1293557019 {\n  width: 100%;\n}\n<\/style>\n\t<\/div>\n\t\n\n<p style=\"text-align: center;\"><span style=\"font-size: 130%; color: #333399;\">PFH<sub>D<\/sub> = PFH<sub>D1<\/sub> + PFH<sub>D2<\/sub> + PFH<sub>D3<\/sub><\/span><\/p>\n<p>The PL of the SRP\/CS is derived by entering the total PFHD value in the following table.<\/p>\n<table style=\"border-collapse: collapse; width: 100%; height: 147px;\">\n<tbody>\n<tr style=\"height: 21px;\">\n<td style=\"width: 4.06427%; height: 21px;\">PL<\/td>\n<td style=\"width: 95.9357%; height: 21px;\">Average probability of dangerous failure (PFH<sub>D<\/sub>)<\/td>\n<\/tr>\n<tr style=\"height: 21px;\">\n<td style=\"width: 4.06427%; height: 21px;\">a<\/td>\n<td style=\"width: 95.9357%; height: 21px;\">\u2265 10<sup>-5<\/sup> to &lt; 10<sup>-4<\/sup><\/td>\n<\/tr>\n<tr style=\"height: 21px;\">\n<td style=\"width: 4.06427%; height: 21px;\">b<\/td>\n<td style=\"width: 95.9357%; height: 21px;\">\u2265 3 x 10<sup>-6<\/sup> to &lt; 10<sup>-5<\/sup><\/td>\n<\/tr>\n<tr style=\"height: 21px;\">\n<td style=\"width: 4.06427%; height: 21px;\">c<\/td>\n<td style=\"width: 95.9357%; height: 21px;\">\u2265 10<sup>-6<\/sup> to &lt; 3 x10<sup>-6<\/sup><\/td>\n<\/tr>\n<tr style=\"height: 21px;\">\n<td style=\"width: 4.06427%; height: 21px;\">d<\/td>\n<td style=\"width: 95.9357%; height: 21px;\">\u2265 10<sup>-7<\/sup> to &lt; 10<sup>-6<\/sup><\/td>\n<\/tr>\n<tr style=\"height: 42px;\">\n<td style=\"width: 4.06427%; height: 42px;\">e<\/td>\n<td style=\"width: 95.9357%; height: 42px;\">\u2265 10<sup>-8<\/sup> to &lt; 10<sup>-7<\/sup><\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p style=\"text-align: center;\">Fig. 13 &#8211; Table 3 of ISO 13849-1 standard: Performance levels (PL)<\/p>\n<h4>Numerical Example:<\/h4>\n\t<div class=\"img has-hover x md-x lg-x y md-y lg-y\" id=\"image_98921747\">\n\t\t\t\t\t\t\t\t<div class=\"img-inner dark\" >\n\t\t\t<img width=\"1020\" height=\"408\" src=\"https:\/\/www.reersafety.cn\/wp-content\/uploads\/2021\/07\/EN_deatailed-method-Example-1024x410.png\" class=\"attachment-large size-large\" alt=\"\" decoding=\"async\" loading=\"lazy\" srcset=\"https:\/\/www.reersafety.cn\/wp-content\/uploads\/2021\/07\/EN_deatailed-method-Example-1024x410.png 1024w, https:\/\/www.reersafety.cn\/wp-content\/uploads\/2021\/07\/EN_deatailed-method-Example-300x120.png 300w, https:\/\/www.reersafety.cn\/wp-content\/uploads\/2021\/07\/EN_deatailed-method-Example-768x308.png 768w, https:\/\/www.reersafety.cn\/wp-content\/uploads\/2021\/07\/EN_deatailed-method-Example-1536x615.png 1536w, https:\/\/www.reersafety.cn\/wp-content\/uploads\/2021\/07\/EN_deatailed-method-Example-2048x821.png 2048w, https:\/\/www.reersafety.cn\/wp-content\/uploads\/2021\/07\/EN_deatailed-method-Example-510x204.png 510w\" sizes=\"(max-width: 1020px) 100vw, 1020px\" \/>\t\t\t\t\t\t\n\t\t\t\t\t<\/div>\n\t\t\t\t\t\t\t\t\n<style>\n#image_98921747 {\n  width: 100%;\n}\n<\/style>\n\t<\/div>\n\t\n\n<p>The PL corresponding to the PFH<sub>D<\/sub> thus calculated is then limited by systematic constraints. The total PL cannot be greater than the lowest PL of all the subsystems that realize the safety function.<\/p>\n<h4>Limitation example:<\/h4>\n<p>The safety function consists of a Type 2 Photoelectric light curtain, PL c, a PL e control unit and a PL d drive<\/p>\n<p>Summing the PFH<sub>D<\/sub> values it results:<\/p>\n\t<div class=\"img has-hover x md-x lg-x y md-y lg-y\" id=\"image_2070129358\">\n\t\t\t\t\t\t\t\t<div class=\"img-inner dark\" >\n\t\t\t<img width=\"1020\" height=\"408\" src=\"https:\/\/www.reersafety.cn\/wp-content\/uploads\/2021\/07\/EN_deatailed-method-limitation-Example-1024x410.png\" class=\"attachment-large size-large\" alt=\"\" decoding=\"async\" loading=\"lazy\" srcset=\"https:\/\/www.reersafety.cn\/wp-content\/uploads\/2021\/07\/EN_deatailed-method-limitation-Example-1024x410.png 1024w, https:\/\/www.reersafety.cn\/wp-content\/uploads\/2021\/07\/EN_deatailed-method-limitation-Example-300x120.png 300w, https:\/\/www.reersafety.cn\/wp-content\/uploads\/2021\/07\/EN_deatailed-method-limitation-Example-768x308.png 768w, https:\/\/www.reersafety.cn\/wp-content\/uploads\/2021\/07\/EN_deatailed-method-limitation-Example-1536x615.png 1536w, https:\/\/www.reersafety.cn\/wp-content\/uploads\/2021\/07\/EN_deatailed-method-limitation-Example-2048x821.png 2048w, https:\/\/www.reersafety.cn\/wp-content\/uploads\/2021\/07\/EN_deatailed-method-limitation-Example-510x204.png 510w\" sizes=\"(max-width: 1020px) 100vw, 1020px\" \/>\t\t\t\t\t\t\n\t\t\t\t\t<\/div>\n\t\t\t\t\t\t\t\t\n<style>\n#image_2070129358 {\n  width: 100%;\n}\n<\/style>\n\t<\/div>\n\t\n\n<p>Entering 5.33&#215;10<sup>-7<\/sup> into the table, it follows that the resulting PL should be PL d<\/p>\n<p style=\"text-align: left;\">However, remembering the constraints due to systematic failures to which Type 2, photoelectric light curtains are subjected:<\/p>\n<table style=\"border-collapse: collapse; width: 100%;\">\n<tbody>\n<tr>\n<td style=\"width: 33.3333%;\">ESPE TYPE<\/td>\n<td style=\"width: 33.3333%;\">PL<\/td>\n<td style=\"width: 33.3333%;\">SIL<\/td>\n<\/tr>\n<tr>\n<td style=\"width: 33.3333%;\">2<\/td>\n<td style=\"width: 33.3333%;\">a, b, c<\/td>\n<td style=\"width: 33.3333%;\">1<\/td>\n<\/tr>\n<tr>\n<td style=\"width: 33.3333%;\">3<\/td>\n<td style=\"width: 33.3333%;\">a, b, c, d<\/td>\n<td style=\"width: 33.3333%;\">1, 2<\/td>\n<\/tr>\n<tr>\n<td style=\"width: 33.3333%;\">4<\/td>\n<td style=\"width: 33.3333%;\">a, b ,c ,d<\/td>\n<td style=\"width: 33.3333%;\">1, 2, 3<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p style=\"text-align: left;\">Fig. 14 &#8211; Maximum PL for a safety function using safety light curtains<\/p>\n<p>It comes that the maximum PL that can be reached by the safety function is limited to PL c<\/p>\n\n<\/div><\/div>\n<div class=\"accordion-item\"><a href=\"#\" class=\"accordion-title plain\"><button class=\"toggle\"><i class=\"icon-angle-down\"><\/i><\/button><span>Simplified method<\/span><\/a><div class=\"accordion-inner\">\n\n<p>If it is known only the PL of the individual subsystems, an estimate PL of the combination can be derived by using the following table::<\/p>\n<table style=\"border-collapse: collapse; width: 52.1739%; height: 126px;\">\n<tbody>\n<tr style=\"height: 21px;\">\n<td style=\"width: 13.6578%; height: 21px;\">PL (low)<\/td>\n<td style=\"width: 11.5785%; height: 21px;\">n (low)<\/td>\n<td style=\"width: 10.2552%; height: 21px;\">\u00a0<\/td>\n<td style=\"width: 16.6824%; height: 21px;\">PL<\/td>\n<\/tr>\n<tr style=\"height: 21px;\">\n<td style=\"width: 13.6578%; height: 21px;\">a<\/td>\n<td style=\"width: 11.5785%; height: 21px;\">&gt;3<br \/>\u2264 3<\/td>\n<td style=\"width: 10.2552%; height: 21px;\">--><\/td>\n<td style=\"width: 16.6824%; height: 21px;\">\n<p>&#8211;<br \/>a<\/p>\n<\/td>\n<\/tr>\n<tr style=\"height: 21px;\">\n<td style=\"width: 13.6578%; height: 21px;\">b<\/td>\n<td style=\"width: 11.5785%; height: 21px;\">&gt;2<br \/>\u2264 2<\/td>\n<td style=\"width: 10.2552%; height: 21px;\">--><\/td>\n<td style=\"width: 16.6824%; height: 21px;\">\n<p>a<br \/>b<\/p>\n<\/td>\n<\/tr>\n<tr style=\"height: 21px;\">\n<td style=\"width: 13.6578%; height: 21px;\">c<\/td>\n<td style=\"width: 11.5785%; height: 21px;\">&gt;2<br \/>\u2264 3<\/td>\n<td style=\"width: 10.2552%; height: 21px;\">--><\/td>\n<td style=\"width: 16.6824%; height: 21px;\">\n<p>b<br \/>c<\/p>\n<\/td>\n<\/tr>\n<tr style=\"height: 21px;\">\n<td style=\"width: 13.6578%; height: 21px;\">d<\/td>\n<td style=\"width: 11.5785%; height: 21px;\">&gt;3<br \/>\u2264 3<\/td>\n<td style=\"width: 10.2552%; height: 21px;\">--><\/td>\n<td style=\"width: 16.6824%; height: 21px;\">\n<p>c<br \/>d<\/p>\n<\/td>\n<\/tr>\n<tr style=\"height: 21px;\">\n<td style=\"width: 13.6578%; height: 21px;\">e<\/td>\n<td style=\"width: 11.5785%; height: 21px;\">&gt;3<br \/>\u2264 3<\/td>\n<td style=\"width: 10.2552%; height: 21px;\">--><\/td>\n<td style=\"width: 16.6824%; height: 21px;\">\n<p>d<br \/>e<\/p>\n<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p style=\"text-align: center;\">Fig. 15 &#8211; Table for total PL computation<\/p>\n<p>If the PFH<sub>d<\/sub> values of all individual SRP\/CSs are not know: Locate the part with PL = PL low. Find the number of parts having PL = PL low<\/p>\n<ul>\n<li>Identify the part with the lowest PL is identified &#8220;PL (low)&#8221; first column<\/li>\n<li>Identify the number of parts with the lowest PL are identified &#8220;n (low)&#8221; second column<\/li>\n<li>The total PL is found in the corresponding row of the third column<\/li>\n<\/ul>\n<p>Note: The PL obtained through this approximation refers to PFH<sub>D<\/sub> values that are in the middle of the range of the corresponding PL\u00a0<\/p>\n<p>In the proposed example of Fig. 15:<\/p>\n\t<div class=\"img has-hover x md-x lg-x y md-y lg-y\" id=\"image_805203595\">\n\t\t\t\t\t\t\t\t<div class=\"img-inner dark\" >\n\t\t\t<img width=\"1020\" height=\"408\" src=\"https:\/\/www.reersafety.cn\/wp-content\/uploads\/2021\/07\/EN_simplified-method-Example-1024x410.png\" class=\"attachment-large size-large\" alt=\"\" decoding=\"async\" loading=\"lazy\" srcset=\"https:\/\/www.reersafety.cn\/wp-content\/uploads\/2021\/07\/EN_simplified-method-Example-1024x410.png 1024w, https:\/\/www.reersafety.cn\/wp-content\/uploads\/2021\/07\/EN_simplified-method-Example-300x120.png 300w, https:\/\/www.reersafety.cn\/wp-content\/uploads\/2021\/07\/EN_simplified-method-Example-768x308.png 768w, https:\/\/www.reersafety.cn\/wp-content\/uploads\/2021\/07\/EN_simplified-method-Example-1536x615.png 1536w, https:\/\/www.reersafety.cn\/wp-content\/uploads\/2021\/07\/EN_simplified-method-Example-2048x821.png 2048w, https:\/\/www.reersafety.cn\/wp-content\/uploads\/2021\/07\/EN_simplified-method-Example-510x204.png 510w\" sizes=\"(max-width: 1020px) 100vw, 1020px\" \/>\t\t\t\t\t\t\n\t\t\t\t\t<\/div>\n\t\t\t\t\t\t\t\t\n<style>\n#image_805203595 {\n  width: 100%;\n}\n<\/style>\n\t<\/div>\n\t\n\n\n<\/div><\/div>\n\n<\/div>\n\t<div id=\"text-3066397532\" class=\"text cutom-ul\">\n\t\t\n\n<h3>Subsystem interconnections<\/h3>\n<p>It is also necessary to give particular attention to the interfaces between subsystems:<\/p>\n<p>The safety aspects related to the interfaces and connections between SRP\/CS (e.g conductors or data communication bus) must be included in the PL of one of the associated\u00a0Subsystems, otherwise connection errors must be excluded or negligible.<\/p>\n<p>The cascade of safety subsystems must have compatible interfaces. Each subsystem output must be suitable for initiating the safe state of the downstream subsystem.<\/p>\n\t\t\t<\/div>\n\t\n\t<div id=\"gap-1085398253\" class=\"gap-element clearfix\" style=\"display:block; height:auto;\">\n\t\t\n<style>\n#gap-1085398253 {\n  padding-top: 30px;\n}\n<\/style>\n\t<\/div>\n\t\n\n<div class=\"is-divider divider clearfix\" style=\"max-width:100px;\"><\/div>\n\n<div class=\"row\"  id=\"row-1896508346\">\n\n\n\t<div id=\"col-348601815\" class=\"col medium-4 small-12 large-4\"  >\n\t\t<div class=\"col-inner\"  >\n\t\t\t\n\t\t\t\n\n\t<div class=\"ux-menu stack stack-col justify-start ux-menu--divider-solid\">\n\t\t\n\n\t<div class=\"ux-menu-link flex menu-item\">\n\t\t<a class=\"ux-menu-link__link flex\" href=\"https:\/\/www.reersafety.cn\/en\/academy\/industrial-safety-guide\/iso-13849-12safety-of-machinery\/ccf-evaluation-for-redundant-architectures\/\"  >\n\t\t\t<i class=\"ux-menu-link__icon text-center icon-angle-left\" ><\/i>\t\t\t<span class=\"ux-menu-link__text\">\n\t\t\t\tCCF evaluation for redundant architectures\t\t\t<\/span>\n\t\t<\/a>\n\t<\/div>\n\t\n\n\n\t<\/div>\n\t\n\n\t\t<\/div>\n\t\t\t<\/div>\n\n\t\n\n\t<div id=\"col-1331215431\" class=\"col medium-4 small-12 large-4\"  >\n\t\t<div class=\"col-inner\"  >\n\t\t\t\n\t\t\t\n\n\n\t\t<\/div>\n\t\t\t<\/div>\n\n\t\n\n\t<div id=\"col-982445048\" class=\"col medium-4 small-12 large-4\"  >\n\t\t<div class=\"col-inner text-right\"  >\n\t\t\t\n\t\t\t\n\n\t<div class=\"ux-menu stack stack-col justify-start ux-menu--divider-solid\">\n\t\t\n\n\t<div class=\"ux-menu-link flex menu-item\">\n\t\t<a class=\"ux-menu-link__link flex\" href=\"https:\/\/www.reersafety.cn\/en\/academy\/industrial-safety-guide\/iec-62061-safety-of-machinery\/\"  >\n\t\t\t<i class=\"ux-menu-link__icon text-center icon-angle-right\" ><\/i>\t\t\t<span class=\"ux-menu-link__text\">\n\t\t\t\tIEC 62061\tSafety of machinery\t\t\t<\/span>\n\t\t<\/a>\n\t<\/div>\n\t\n\n\n\t<\/div>\n\t\n\n\t\t<\/div>\n\t\t\t<\/div>\n\n\t\n\n<\/div>\n\n\t\t<\/div>\n\t\t\t<\/div>\n\n\t\n\n<\/div>\n\n\t\t<\/div>\n\t\t\t<\/div>\n\n\t\n\n<\/div>\n\n","protected":false},"excerpt":{"rendered":"","protected":false},"author":7,"featured_media":0,"parent":54342,"menu_order":0,"comment_status":"closed","ping_status":"closed","template":"","meta":{"om_disable_all_campaigns":false,"inline_featured_image":false,"_monsterinsights_skip_tracking":false,"_monsterinsights_sitenote_active":false,"_monsterinsights_sitenote_note":"","_monsterinsights_sitenote_category":0,"_uf_show_specific_survey":0,"_uf_disable_surveys":false},"acf":[],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v20.1 - https:\/\/yoast.com\/wordpress\/plugins\/seo\/ -->\n<title>Simplified method for estimating the quantifiable part of the PL | ReeR<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, 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