{"id":100286,"date":"2026-02-15T20:31:54","date_gmt":"2026-02-15T20:31:54","guid":{"rendered":"https:\/\/vibromera.eu\/?post_type=calculator&#038;p=100286"},"modified":"2026-04-05T15:33:54","modified_gmt":"2026-04-05T15:33:54","slug":"vibration-iso20816-2-turbines","status":"publish","type":"calculator","link":"https:\/\/vibromera.eu\/bn\/calculators\/vibration-iso20816-2-turbines\/","title":{"rendered":"ISO 20816-2 Vibration Limits: Steam Turbines &#038; Generators"},"content":{"rendered":"\n<script type=\"application\/ld+json\">\n{\"@context\":\"https:\/\/schema.org\",\"@type\":\"WebApplication\",\"name\":\"Vibration Limits Calculator \u2014 ISO 20816-2 Steam Turbines\",\"alternateName\":[\"ISO 20816-2 Calculator\",\"Steam Turbine Vibration Limits\",\"Generator Vibration Evaluation\"],\"description\":\"Free online vibration zone evaluation calculator per ISO 20816-2 for steam turbines and generators over 40 MW.\",\"url\":\"https:\/\/vibromera.eu\/calculators\/vibration-iso20816-2-turbines\/\",\"applicationCategory\":\"Engineering Calculator\",\"operatingSystem\":\"Any (Web Browser)\",\"offers\":{\"@type\":\"Offer\",\"price\":\"0\",\"priceCurrency\":\"EUR\"},\"creator\":{\"@type\":\"Organization\",\"name\":\"Vibromera\",\"url\":\"https:\/\/vibromera.eu\/\"},\"datePublished\":\"2025-01-01\",\"dateModified\":\"2025-02-14\",\"inLanguage\":\"en\",\"isAccessibleForFree\":true,\"featureList\":[\"ISO 20816-2 zone evaluation\",\"Bearing housing velocity\",\"Shaft relative displacement\",\"Steam turbines and generators\",\"Color-coded zone display\"],\"keywords\":\"vibration limits, ISO 20816-2, steam turbine, generator, zone A B C D\"}\n<\/script>\n\n<script type=\"application\/ld+json\">\n{\"@context\":\"https:\/\/schema.org\",\"@type\":\"FAQPage\",\"mainEntity\":[\n{\"@type\":\"Question\",\"name\":\"What machines does ISO 20816-2 cover?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"ISO 20816-2 applies to steam turbines and generators with power output greater than 40 MW and operating speeds between 1500 and 3600 RPM. This includes large power station turbine-generator sets, industrial steam turbines, and combined-cycle plant generators.\"}},\n{\"@type\":\"Question\",\"name\":\"What is the difference between bearing housing and shaft relative measurement?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"Bearing housing vibration is measured with accelerometers or velocity sensors mounted on the bearing cap, expressed in mm\/s RMS. Shaft relative vibration is measured with proximity probes installed inside the bearing, measuring shaft displacement relative to the bearing, expressed in \u03bcm peak-to-peak. Both should be monitored for a complete picture.\"}},\n{\"@type\":\"Question\",\"name\":\"Why are shaft vibration limits important for steam turbines?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"Steam turbines use fluid-film (journal) bearings where the bearing housing may not vibrate significantly even when the shaft has high vibration. Shaft relative measurement captures the actual rotor dynamic behavior, detecting issues like unbalance, misalignment, oil whirl, and rotor cracks that bearing housing sensors might miss.\"}},\n{\"@type\":\"Question\",\"name\":\"What should I do if vibration reaches Zone C?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"For Zone C on steam turbines: investigate the root cause immediately, increase monitoring frequency, plan corrective action during the next scheduled outage, inform plant management. The turbine may continue operating for a limited period but should not remain in Zone C indefinitely. Common causes include unbalance, misalignment, bearing wear, and thermal bowing.\"}},\n{\"@type\":\"Question\",\"name\":\"How does ISO 20816-2 relate to ISO 7919-2?\",\"acceptedAnswer\":{\"@type\":\"Answer\",\"text\":\"ISO 20816-2 consolidates the content of the former ISO 10816-2 (bearing housing vibration) and ISO 7919-2 (shaft vibration) into a single standard. 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}\n.vc-promo-text strong { color:var(--vc-ink); }\n.vc-promo-link { padding:8px 20px; font-size:13px; font-weight:700; color:#fff; background:var(--vc-accent); border-radius:var(--vc-radius); text-decoration:none; white-space:nowrap; transition:background 0.15s; }\n.vc-promo-link:hover { background:var(--vc-accent-hover); }\n\n.vc-footer { text-align:center; padding:32px 16px; font-size:13px; color:var(--vc-ink-muted); }\n.vc-footer a { color:var(--vc-accent); text-decoration:none; }\n.vc-footer a:hover { text-decoration:underline; }\n.vc-footer-links { margin-top:8px; font-size:12px; }\n.vc-footer-links a { margin:0 8px; }\n\n@media print {\n    .vc-section-body { max-height:none!important; }\n    .vc-faq-a { max-height:none!important; }\n    .vc-results { max-height:none!important; padding:24px!important; }\n    .vc-copy-btn, .vc-section-chevron, .vc-faq-chevron, .vc-presets, .vc-promo { display:none!important; }\n}\n<\/style>\n\n<div class=\"vc-calculator\" id=\"vc-iso20816-2\">\n\n<header class=\"vc-header\">\n    <p class=\"vc-header-eyebrow\">Free Engineering Tool #020<\/p>\n    <h1 class=\"vc-header-title\">Vibration Limits \u2014 Steam Turbines &amp; Generators &gt;40 MW<\/h1>\n    <p class=\"vc-header-subtitle\">Evaluate vibration severity for steam turbines and generators per ISO 20816-2. Supports bearing housing velocity and shaft relative displacement measurements.<\/p>\n    <div class=\"vc-badges\">\n        <span class=\"vc-badge\">ISO 20816-2<\/span>\n        <span class=\"vc-badge\">Zones A\/B\/C\/D<\/span>\n        <span class=\"vc-badge\">&gt;40 MW<\/span>\n    <\/div>\n<\/header>\n\n<div class=\"vc-card\">\n    <form class=\"vc-form\" id=\"vc-form\" autocomplete=\"off\">\n        <div class=\"vc-form-grid\">\n            <div class=\"vc-field\">\n                <label class=\"vc-label\" for=\"vc-machine\">Machine Type<\/label>\n                <select class=\"vc-select\" id=\"vc-machine\">\n                    <option value=\"turbine\" selected>Steam Turbine<\/option>\n                    <option value=\"generator\">Generator<\/option>\n                    <option value=\"combined\">Combined Turbine-Generator<\/option>\n                <\/select>\n            <\/div>\n            <div class=\"vc-field\">\n                <label class=\"vc-label\" for=\"vc-location\">Measurement Location<\/label>\n                <select class=\"vc-select\" id=\"vc-location\">\n                    <option value=\"bearing\" selected>Bearing Housing (velocity, mm\/s RMS)<\/option>\n                    <option value=\"shaft\">Shaft Relative (displacement, \u03bcm p-p)<\/option>\n                <\/select>\n            <\/div>\n            <div class=\"vc-field vc-field-full\">\n                <label class=\"vc-label\" for=\"vc-value\">Measured Value <span class=\"vc-label-hint\" id=\"vc-value-hint\">(mm\/s RMS)<\/span><\/label>\n                <input class=\"vc-input\" type=\"number\" id=\"vc-value\" inputmode=\"decimal\" step=\"any\" min=\"0\" placeholder=\"e.g. 4.2\" value=\"4.2\">\n            <\/div>\n        <\/div>\n\n        <div class=\"vc-presets\">\n            <div class=\"vc-presets-label\">Quick presets<\/div>\n            <button type=\"button\" class=\"vc-preset-btn\" data-m=\"turbine\" data-l=\"bearing\" data-v=\"4.2\">Turbine bearing 4.2 mm\/s<\/button>\n            <button type=\"button\" class=\"vc-preset-btn\" data-m=\"generator\" data-l=\"shaft\" data-v=\"80\">Generator shaft 80 \u03bcm<\/button>\n            <button type=\"button\" class=\"vc-preset-btn\" data-m=\"turbine\" data-l=\"shaft\" data-v=\"120\">Turbine shaft 120 \u03bcm<\/button>\n        <\/div>\n    <\/form>\n\n    <div class=\"vc-results\" id=\"vc-results\">\n        <div class=\"vc-results-head\">\n            <h2 class=\"vc-results-title\">Results<\/h2>\n            <button type=\"button\" class=\"vc-copy-btn\" id=\"vc-copy-btn\">\n                <svg width=\"14\" height=\"14\" viewBox=\"0 0 24 24\" fill=\"none\" stroke=\"currentColor\" stroke-width=\"2\"><rect x=\"9\" y=\"9\" width=\"13\" height=\"13\" rx=\"2\"\/><path d=\"M5 15H4a2 2 0 01-2-2V4a2 2 0 012-2h9a2 2 0 012 2v1\"\/><\/svg>\n                Copy\n            <\/button>\n        <\/div>\n\n        <div class=\"vc-zone-bar\" id=\"vc-zone-bar\">\n            <div class=\"vc-zone-bar-seg zb-a\" id=\"zb-a\">A<\/div>\n            <div class=\"vc-zone-bar-seg zb-b\" id=\"zb-b\">B<\/div>\n            <div class=\"vc-zone-bar-seg zb-c\" id=\"zb-c\">C<\/div>\n            <div class=\"vc-zone-bar-seg zb-d\" id=\"zb-d\">D<\/div>\n        <\/div>\n        <div class=\"vc-zone-bar-labels\" id=\"vc-zone-labels\">\n            <span id=\"zl-a\"><\/span><span id=\"zl-b\"><\/span><span id=\"zl-c\"><\/span><span id=\"zl-d\"><\/span>\n        <\/div>\n\n        <div class=\"vc-result-grid\">\n            <div class=\"vc-rcard vc-rcard-primary\" id=\"vc-r-zone-card\">\n                <div class=\"vc-rcard-label\">Vibration Zone<\/div>\n                <div class=\"vc-rcard-value\" id=\"vc-r-zone\">\u2014<\/div>\n                <div class=\"vc-rcard-desc\" id=\"vc-r-zone-desc\"><\/div>\n            <\/div>\n            <div class=\"vc-rcard\">\n                <div class=\"vc-rcard-label\">Measured Value<\/div>\n                <div class=\"vc-rcard-value\" id=\"vc-r-measured\">\u2014<\/div>\n            <\/div>\n            <div class=\"vc-rcard\">\n                <div class=\"vc-rcard-label\">Recommendation<\/div>\n                <div class=\"vc-rcard-value\" id=\"vc-r-action\" style=\"font-size:16px;\">\u2014<\/div>\n            <\/div>\n        <\/div>\n\n        <table class=\"vc-zone-table\" id=\"vc-boundary-table\">\n            <thead><tr><th>Zone<\/th><th>Boundary<\/th><th>Description<\/th><\/tr><\/thead>\n            <tbody id=\"vc-boundary-body\"><\/tbody>\n        <\/table>\n    <\/div>\n<\/div>\n\n<!-- Theory -->\n<div class=\"vc-section vc-open\" id=\"vc-sec-theory\">\n    <button type=\"button\" class=\"vc-section-toggle\" aria-expanded=\"true\">\n        <span class=\"vc-section-toggle-text\">\n            <span class=\"vc-section-icon\">\ud83d\udcd8<\/span>\n            <span class=\"vc-section-title\">Theory &amp; Formulas<\/span>\n        <\/span>\n        <svg class=\"vc-section-chevron\" viewBox=\"0 0 24 24\" fill=\"none\" stroke=\"currentColor\" stroke-width=\"2\"><path d=\"M6 9l6 6 6-6\"\/><\/svg>\n    <\/button>\n    <div class=\"vc-section-body\">\n        <div class=\"vc-section-inner vc-theory\">\n            <h3>ISO 20816-2 Scope<\/h3>\n            <p>ISO 20816-2 specifies vibration evaluation criteria for steam turbines and generators exceeding 40 MW output, operating at speeds between 1500 and 3600 RPM (50\/60 Hz power generation). It covers both bearing housing vibration and shaft relative vibration.<\/p>\n            <div class=\"vc-formula-box\" id=\"vc-katex-1\"><\/div>\n\n            <h3>Bearing Housing Vibration<\/h3>\n            <p>Broadband vibration velocity is measured on the bearing housing (pedestal) in mm\/s RMS, typically in the frequency range 10\u20131000 Hz.<\/p>\n            <table class=\"vc-table\">\n                <thead><tr><th>Zone Boundary<\/th><th>Velocity (mm\/s RMS)<\/th><\/tr><\/thead>\n                <tbody>\n                    <tr><td>A\/B<\/td><td>2.8<\/td><\/tr>\n                    <tr><td>B\/C<\/td><td>5.3<\/td><\/tr>\n                    <tr><td>C\/D<\/td><td>8.5<\/td><\/tr>\n                <\/tbody>\n            <\/table>\n\n            <h3>Shaft Relative Displacement<\/h3>\n            <p>Shaft vibration is measured with proximity probes, expressed as peak-to-peak displacement in \u03bcm. These values are simplified for general application.<\/p>\n            <div class=\"vc-formula-box\" id=\"vc-katex-2\"><\/div>\n            <table class=\"vc-table\">\n                <thead><tr><th>Zone Boundary<\/th><th>Displacement (\u03bcm p-p)<\/th><\/tr><\/thead>\n                <tbody>\n                    <tr><td>A\/B<\/td><td>50<\/td><\/tr>\n                    <tr><td>B\/C<\/td><td>100<\/td><\/tr>\n                    <tr><td>C\/D<\/td><td>165<\/td><\/tr>\n                <\/tbody>\n            <\/table>\n\n            <div class=\"vc-info-box\">\n                <p><strong>\u2139\ufe0f Note:<\/strong> Shaft displacement limits may vary with operating speed. The values above are simplified for general use. For exact speed-dependent limits, consult the full ISO 20816-2 standard.<\/p>\n            <\/div>\n\n            <div class=\"vc-warning-box\">\n                <p style=\"margin:0;font-size:14px;color:var(--vc-ink-secondary);\"><strong>\u26a0\ufe0f Important:<\/strong> Both bearing housing and shaft vibration should be monitored. A machine may show low bearing housing vibration but high shaft vibration, or vice versa. The worse of the two assessments governs the overall evaluation.<\/p>\n            <\/div>\n        <\/div>\n    <\/div>\n<\/div>\n\n<!-- Related -->\n<div class=\"vc-section\" id=\"vc-sec-related\">\n    <button type=\"button\" class=\"vc-section-toggle\" aria-expanded=\"false\">\n        <span class=\"vc-section-toggle-text\">\n            <span class=\"vc-section-icon\">\ud83d\udd17<\/span>\n            <span class=\"vc-section-title\">Related Calculators<\/span>\n        <\/span>\n        <svg class=\"vc-section-chevron\" viewBox=\"0 0 24 24\" fill=\"none\" stroke=\"currentColor\" stroke-width=\"2\"><path d=\"M6 9l6 6 6-6\"\/><\/svg>\n    <\/button>\n    <div class=\"vc-section-body\">\n        <div class=\"vc-section-inner\">\n            <div class=\"vc-related\">\n                <a class=\"vc-related-link\" href=\"\/calculators\/vibration-zones-iso20816-1\/\">ISO 20816-1 \u2014 General Guidelines<\/a>\n                <a class=\"vc-related-link\" href=\"\/calculators\/vibration-iso20816-3-industrial\/\">ISO 20816-3 \u2014 Industrial Machines<\/a>\n                <a class=\"vc-related-link\" href=\"\/calculators\/vibration-iso20816-4-gas-turbines\/\">ISO 20816-4 \u2014 Gas Turbines<\/a>\n                <a class=\"vc-related-link\" href=\"\/calculators\/residual-unbalance-iso1940\/\">Residual Unbalance (ISO 21940)<\/a>\n                <a class=\"vc-related-link\" href=\"\/calculators\/vibration-velocity\/\">Vibration Velocity (ISO 10816)<\/a>\n            <\/div>\n        <\/div>\n    <\/div>\n<\/div>\n\n<!-- FAQ -->\n<div class=\"vc-section\" id=\"vc-sec-faq\">\n    <button type=\"button\" class=\"vc-section-toggle\" aria-expanded=\"false\">\n        <span class=\"vc-section-toggle-text\">\n            <span class=\"vc-section-icon\">\u2753<\/span>\n            <span class=\"vc-section-title\">Frequently Asked Questions<\/span>\n        <\/span>\n        <svg class=\"vc-section-chevron\" viewBox=\"0 0 24 24\" fill=\"none\" stroke=\"currentColor\" stroke-width=\"2\"><path d=\"M6 9l6 6 6-6\"\/><\/svg>\n    <\/button>\n    <div class=\"vc-section-body\">\n        <div class=\"vc-section-inner\">\n            <div class=\"vc-faq-list\" id=\"vc-faq-list\"><\/div>\n        <\/div>\n    <\/div>\n<\/div>\n\n<div class=\"vc-promo\">\n    <div class=\"vc-promo-text\">\n        <strong>Vibromera \u2014 Portable Balancing &amp; Vibration Analysis<\/strong><br>\n        Professional vibration analyzers and field balancing systems for turbomachinery. ISO 20816 compliant evaluation on-site. Used in 50+ countries.\n    <\/div>\n    <a class=\"vc-promo-link\" href=\"https:\/\/vibromera.eu\/\" target=\"_blank\" rel=\"noopener\">Learn More<\/a>\n<\/div>\n\n<footer class=\"vc-footer\">\n    <p>\u00a9 2024\u20132025 <a href=\"https:\/\/vibromera.eu\/\">Vibromera<\/a> \u2014 Engineering Calculators<\/p>\n    <p style=\"font-size:12px;margin-top:4px;\">Based on ISO 20816-2. Last updated: February 2025<\/p>\n    <div class=\"vc-footer-links\">\n        <a href=\"\/calculators\/engineering-calculators\/\">All Calculators<\/a>\n        <a href=\"https:\/\/vibromera.eu\/contacts\/\">Contact<\/a>\n    <\/div>\n<\/footer>\n\n<\/div>\n\n<script src=\"https:\/\/cdn.jsdelivr.net\/npm\/katex@0.16.11\/dist\/katex.min.js\"><\/script>\n<script>\n(function() {\n    'use strict';\n\n    var SLUG = 'vibration-iso20816-2-turbines';\n\n    var LIMITS = {\n        bearing: { ab: 2.8, bc: 5.3, cd: 8.5, unit: 'mm\/s RMS' },\n        shaft:   { ab: 50,  bc: 100, cd: 165,  unit: '\u03bcm p-p' }\n    };\n\n    var ZONE_DESC = {\n        A: 'Newly commissioned machines \u2014 excellent condition',\n        B: 'Acceptable for unrestricted long-term operation',\n        C: 'Not suitable for long-term operation \u2014 plan remedial action',\n        D: 'Dangerous vibration level \u2014 risk of damage, immediate action required'\n    };\n\n    var ZONE_ACTION = {\n        A: 'No action required \u2014 machine in excellent condition',\n        B: 'Continue normal operation and routine monitoring',\n        C: 'Investigate root cause; schedule corrective maintenance; increase monitoring',\n        D: 'Immediate shutdown or load reduction recommended \u2014 risk of damage'\n    };\n\n    function $(id) { return document.getElementById(id); }\n    function fmt(n, d) { if(isNaN(n)) return '\u2014'; var f=n.toFixed(d===undefined?2:d); return f.replace(\/(\\.\\d*?)0+$\/,'$1').replace(\/\\.$\/,''); }\n\n    function getZone(val, lim) {\n        if (val <= lim.ab) return 'A';\n        if (val <= lim.bc) return 'B';\n        if (val <= lim.cd) return 'C';\n        return 'D';\n    }\n\n    function calculate() {\n        var machine = $('vc-machine').value;\n        var location = $('vc-location').value;\n        var val = parseFloat($('vc-value').value);\n\n        if (isNaN(val) || val < 0) {\n            $('vc-results').classList.remove('vc-visible');\n            return;\n        }\n\n        var lim = LIMITS[location];\n        var zone = getZone(val, lim);\n\n        ['a','b','c','d'].forEach(function(letter) {\n            var seg = $('zb-' + letter);\n            seg.className = 'vc-zone-bar-seg zb-' + letter + (letter.toUpperCase() === zone ? ' zb-active' : ' zb-dim');\n        });\n\n        $('zl-a').textContent = '\u2264' + lim.ab;\n        $('zl-b').textContent = lim.ab + '\u2013' + lim.bc;\n        $('zl-c').textContent = lim.bc + '\u2013' + lim.cd;\n        $('zl-d').textContent = '>' + lim.cd;\n\n        var zoneCard = $('vc-r-zone-card');\n        zoneCard.className = 'vc-rcard vc-rcard-primary vc-zone-' + zone.toLowerCase();\n        $('vc-r-zone').textContent = 'Zone ' + zone;\n        $('vc-r-zone-desc').textContent = ZONE_DESC[zone];\n\n        $('vc-r-measured').innerHTML = fmt(val, location === 'shaft' ? 0 : 2) + ' <span class=\"vc-rcard-unit\">' + lim.unit + '<\/span>';\n        $('vc-r-action').textContent = ZONE_ACTION[zone];\n\n        var tbody = $('vc-boundary-body');\n        tbody.innerHTML =\n            '<tr class=\"zt-a\"><td><strong>Zone A<\/strong><\/td><td>\u2264 ' + lim.ab + ' ' + lim.unit + '<\/td><td>' + ZONE_DESC.A + '<\/td><\/tr>' +\n            '<tr class=\"zt-b\"><td><strong>Zone B<\/strong><\/td><td>' + lim.ab + ' \u2013 ' + lim.bc + ' ' + lim.unit + '<\/td><td>' + ZONE_DESC.B + '<\/td><\/tr>' +\n            '<tr class=\"zt-c\"><td><strong>Zone C<\/strong><\/td><td>' + lim.bc + ' \u2013 ' + lim.cd + ' ' + lim.unit + '<\/td><td>' + ZONE_DESC.C + '<\/td><\/tr>' +\n            '<tr class=\"zt-d\"><td><strong>Zone D<\/strong><\/td><td>&gt; ' + lim.cd + ' ' + lim.unit + '<\/td><td>' + ZONE_DESC.D + '<\/td><\/tr>';\n\n        $('vc-results').classList.add('vc-visible');\n\n        var u = new URL(window.location);\n        u.searchParams.set('machine', machine);\n        u.searchParams.set('location', location);\n        u.searchParams.set('value', val);\n        history.replaceState(null, '', u.toString());\n\n        var machineNames = { turbine: 'Steam Turbine', generator: 'Generator', combined: 'Combined' };\n        var locNames = { bearing: 'Bearing housing', shaft: 'Shaft relative' };\n        saveHistory({ machine: machine, location: location, value: val, zone: zone, _summary: machineNames[machine] + ', ' + locNames[location] + ' ' + val + ' ' + lim.unit + ' \u2192 Zone ' + zone });\n    }\n\n    $('vc-location').addEventListener('change', function() {\n        $('vc-value-hint').textContent = this.value === 'bearing' ? '(mm\/s RMS)' : '(\u03bcm p-p)';\n        calculate();\n    });\n\n    document.querySelectorAll('.vc-preset-btn').forEach(function(btn) {\n        btn.addEventListener('click', function(e) {\n            e.preventDefault();\n            $('vc-machine').value = this.getAttribute('data-m');\n            $('vc-location').value = this.getAttribute('data-l');\n            $('vc-value').value = this.getAttribute('data-v');\n            $('vc-value-hint').textContent = this.getAttribute('data-l') === 'bearing' ? '(mm\/s RMS)' : '(\u03bcm p-p)';\n            calculate();\n        });\n    });\n\n    $('vc-form').addEventListener('input', calculate);\n    $('vc-form').addEventListener('change', calculate);\n\n    $('vc-copy-btn').addEventListener('click', function() {\n        var text = 'Vibration Zone Evaluation \u2014 ISO 20816-2\\n' +\n            '\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\\n' +\n            'Machine: ' + $('vc-machine').options[$('vc-machine').selectedIndex].text + '\\n' +\n            'Measurement: ' + $('vc-location').options[$('vc-location').selectedIndex].text + '\\n' +\n            'Measured: ' + $('vc-r-measured').textContent + '\\n' +\n            'Zone: ' + $('vc-r-zone').textContent + '\\n' +\n            'Assessment: ' + $('vc-r-zone-desc').textContent + '\\n' +\n            '\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\u2501\\n' +\n            'vibromera.eu\/calculators\/vibration-iso20816-2-turbines\/';\n\n        if (navigator.clipboard) {\n            navigator.clipboard.writeText(text).then(function() {\n                var btn = $('vc-copy-btn');\n                btn.classList.add('vc-copied');\n                btn.innerHTML = '<svg width=\"14\" height=\"14\" viewBox=\"0 0 24 24\" fill=\"none\" stroke=\"currentColor\" stroke-width=\"2\"><polyline points=\"20 6 9 17 4 12\"\/><\/svg> Copied!';\n                setTimeout(function() {\n                    btn.classList.remove('vc-copied');\n                    btn.innerHTML = '<svg width=\"14\" height=\"14\" viewBox=\"0 0 24 24\" fill=\"none\" stroke=\"currentColor\" stroke-width=\"2\"><rect x=\"9\" y=\"9\" width=\"13\" height=\"13\" rx=\"2\"\/><path d=\"M5 15H4a2 2 0 01-2-2V4a2 2 0 012-2h9a2 2 0 012 2v1\"\/><\/svg> Copy';\n                }, 2000);\n            });\n        }\n    });\n\n    document.querySelectorAll('.vc-section-toggle').forEach(function(btn) {\n        btn.addEventListener('click', function() {\n            var section = this.closest('.vc-section');\n            var isOpen = section.classList.contains('vc-open');\n            section.classList.toggle('vc-open');\n            this.setAttribute('aria-expanded', !isOpen);\n        });\n    });\n\n    var faqData = [\n        { q: 'What machines does ISO 20816-2 cover?', a: '<p>ISO 20816-2 applies to <strong>steam turbines and generators with power output greater than 40 MW<\/strong>, operating at speeds between 1500 and 3600 RPM (for 50\/60 Hz power generation). This includes:<\/p><ul><li>Large power station turbine-generator sets<\/li><li>Industrial steam turbines driving generators<\/li><li>Combined-cycle plant steam turbines<\/li><li>Nuclear power plant turbine-generators<\/li><\/ul>' },\n        { q: 'What is the difference between bearing housing and shaft relative measurement?', a: '<p><strong>Bearing housing vibration<\/strong> is measured with sensors mounted on the bearing pedestal, expressed in mm\/s RMS. It reflects the vibration transmitted through the bearing to the support structure.<\/p><p><strong>Shaft relative vibration<\/strong> is measured with proximity probes inside the bearing, expressed in \u03bcm peak-to-peak. It measures the actual shaft orbit relative to the bearing clearance.<\/p><p>Both measurements are essential \u2014 bearing housing vibration alone may miss internal rotor issues on stiff foundations.<\/p>' },\n        { q: 'Why are shaft vibration limits important for steam turbines?', a: '<p>Steam turbines use fluid-film (journal) bearings where the bearing housing may show low vibration even when the shaft has significant movement. Shaft relative measurement captures:<\/p><ul><li>Rotor unbalance and thermal bowing<\/li><li>Oil whirl and oil whip instabilities<\/li><li>Rotor cracks and rubs<\/li><li>Misalignment between coupled rotors<\/li><\/ul><p>Monitoring shaft vibration is critical for early detection of developing faults.<\/p>' },\n        { q: 'What should I do if vibration reaches Zone C?', a: '<p>For Zone C on a steam turbine or generator:<\/p><ul><li>Immediately notify plant management and operations<\/li><li>Investigate root cause \u2014 check balance condition, alignment, bearing condition, foundation, thermal state<\/li><li>Increase monitoring frequency to continuous if not already<\/li><li>Plan corrective action for the next available outage<\/li><li>Monitor trend \u2014 if approaching Zone D, consider load reduction or planned shutdown<\/li><\/ul>' },\n        { q: 'How does ISO 20816-2 relate to ISO 7919-2?', a: '<p>ISO 20816-2 consolidates the former <strong>ISO 10816-2<\/strong> (bearing housing vibration) and <strong>ISO 7919-2<\/strong> (shaft vibration) for steam turbines into a single unified standard. The zone boundaries are essentially the same, but the new standard provides updated guidance on combined evaluation using both measurement types.<\/p>' }\n    ];\n\n    var faqList = $('vc-faq-list');\n    faqData.forEach(function(faq) {\n        faqList.innerHTML += '<div class=\"vc-faq-item\"><button type=\"button\" class=\"vc-faq-q\"><span>' + faq.q + '<\/span><svg class=\"vc-faq-chevron\" viewBox=\"0 0 24 24\" fill=\"none\" stroke=\"currentColor\" stroke-width=\"2\"><path d=\"M6 9l6 6 6-6\"\/><\/svg><\/button><div class=\"vc-faq-a\"><div class=\"vc-faq-a-inner\">' + faq.a + '<\/div><\/div><\/div>';\n    });\n    faqList.addEventListener('click', function(e) {\n        var btn = e.target.closest('.vc-faq-q');\n        if (!btn) return;\n        btn.closest('.vc-faq-item').classList.toggle('vc-open');\n    });\n\n    function saveHistory(entry) {\n        var key = 'vc_history_' + SLUG;\n        var arr = [];\n        try { arr = JSON.parse(localStorage.getItem(key)) || []; } catch(e) {}\n        entry._ts = new Date().toISOString();\n        arr.unshift(entry);\n        if (arr.length > 10) arr = arr.slice(0, 10);\n        try { localStorage.setItem(key, JSON.stringify(arr)); } catch(e) {}\n    }\n\n    function loadParams() {\n        var p = new URLSearchParams(window.location.search);\n        if (p.has('machine')) $('vc-machine').value = p.get('machine');\n        if (p.has('location')) {\n            $('vc-location').value = p.get('location');\n            $('vc-value-hint').textContent = p.get('location') === 'bearing' ? '(mm\/s RMS)' : '(\u03bcm p-p)';\n        }\n        if (p.has('value')) $('vc-value').value = p.get('value');\n    }\n\n    function renderFormulas() {\n        try {\n            katex.render('\\\\text{Zone} = \\\\begin{cases} A & v_{\\\\text{meas}} \\\\leq v_{A\/B} \\\\\\\\ B & v_{A\/B} < v_{\\\\text{meas}} \\\\leq v_{B\/C} \\\\\\\\ C & v_{B\/C} < v_{\\\\text{meas}} \\\\leq v_{C\/D} \\\\\\\\ D & v_{\\\\text{meas}} > v_{C\/D} \\\\end{cases}', $('vc-katex-1'), { displayMode: true, throwOnError: false });\n            katex.render('s_{\\\\text{p-p}} = s_{\\\\max} - s_{\\\\min} \\\\quad [\\\\mu m]', $('vc-katex-2'), { displayMode: true, throwOnError: false });\n        } catch(e) {}\n    }\n\n    function init() {\n        loadParams();\n        renderFormulas();\n        calculate();\n    }\n\n    if (document.readyState === 'loading') {\n        document.addEventListener('DOMContentLoaded', init);\n    } else {\n        init();\n    }\n})();\n<\/script>\n","protected":false},"excerpt":{"rendered":"<p>Free online vibration zone evaluation calculator per ISO 20816-2 for steam turbines and generators over 40 MW. Evaluate bearing housing velocity and shaft relative displacement against zone A\/B\/C\/D limits.<\/p>","protected":false},"featured_media":0,"template":"","meta":{"ai_generated_summary":"","footnotes":""},"categories":[],"tags":[],"class_list":["post-100286","calculator","type-calculator","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/vibromera.eu\/bn\/wp-json\/wp\/v2\/calculator\/100286","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/vibromera.eu\/bn\/wp-json\/wp\/v2\/calculator"}],"about":[{"href":"https:\/\/vibromera.eu\/bn\/wp-json\/wp\/v2\/types\/calculator"}],"version-history":[{"count":3,"href":"https:\/\/vibromera.eu\/bn\/wp-json\/wp\/v2\/calculator\/100286\/revisions"}],"predecessor-version":[{"id":100908,"href":"https:\/\/vibromera.eu\/bn\/wp-json\/wp\/v2\/calculator\/100286\/revisions\/100908"}],"wp:attachment":[{"href":"https:\/\/vibromera.eu\/bn\/wp-json\/wp\/v2\/media?parent=100286"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/vibromera.eu\/bn\/wp-json\/wp\/v2\/categories?post=100286"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/vibromera.eu\/bn\/wp-json\/wp\/v2\/tags?post=100286"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}