Insulation Resistance Degradation Calculator
ANA›Life Services Authority›National Calculator Authority›Insulation Resistance Degradation Calculator
.calc-container { max-width: 640px; margin: 2rem 0; padding: 1.5rem; background: #fff; border: 1px solid #ddd; border-radius: 8px; box-shadow: 0 1px 3px rgba(0,0,0,0.06); font-family: system-ui, -apple-system, sans-serif; } .calc-container h3 { font-family: Georgia, serif; font-size: 1.15rem; color: #1a1a1a; margin-bottom: 1rem; padding-bottom: 0.5rem; border-bottom: 2px solid var(--ac, #3d5a80); } .calc-row { display: flex; align-items: center; gap: 0.75rem; margin-bottom: 0.75rem; flex-wrap: wrap; } .calc-row label { min-width: 160px; font-size: 0.9rem; color: #333; font-weight: 500; } .calc-row input[type="number"], .calc-row select { flex: 1; min-width: 120px; max-width: 200px; padding: 0.5rem 0.6rem; border: 1px solid #ccc; border-radius: 4px; font-size: 0.9rem; font-family: system-ui, sans-serif; color: #1a1a1a; background: #fafaf8; } .calc-row input:focus, .calc-row select:focus { outline: none; border-color: var(--ac, #3d5a80); box-shadow: 0 0 0 2px rgba(26,74,138,0.12); } .calc-row .unit { font-size: 0.82rem; color: #888; min-width: 30px; } .calc-btn { display: inline-block; margin-top: 0.5rem; padding: 0.55rem 1.5rem; background: var(--ac, #3d5a80); color: #fff; border: none; border-radius: 4px; font-size: 0.9rem; font-weight: 600; cursor: pointer; font-family: system-ui, sans-serif; } .calc-btn:hover { opacity: 0.9; } .calc-result { margin-top: 1.25rem; padding: 1rem 1.25rem; background: #f0f6fc; border-left: 3px solid var(--ac, #3d5a80); border-radius: 0 6px 6px 0; display: none; } .calc-result.visible { display: block; } .calc-result-label { font-size: 0.78rem; text-transform: uppercase; letter-spacing: 0.06em; color: #666; margin-bottom: 0.25rem; } .calc-result-value { font-size: 1.6rem; font-weight: 700; color: var(--ac, #3d5a80); } .calc-result-detail { font-size: 0.85rem; color: #555; margin-top: 0.5rem; line-height: 1.5; } .calc-note { margin-top: 1rem; font-size: 0.8rem; color: #888; font-style: italic; } .calc-grid { display: grid; grid-template-columns: 1fr 1fr; gap: 0.75rem; margin-top: 0.75rem; } .calc-grid-item { padding: 0.6rem 0.8rem; background: #f8f9fa; border-radius: 4px; border: 1px solid #eee; } .calc-grid-item .label { font-size: 0.75rem; color: #888; text-transform: uppercase; letter-spacing: 0.04em; } .calc-grid-item .value { font-size: 1.1rem; font-weight: 600; color: #1a1a1a; } @media (max-width: 720px) { .calc-row { flex-direction: column; align-items: flex-start; gap: 0.3rem; } .calc-row label { min-width: auto; } .calc-row input[type="number"], .calc-row select { max-width: 100%; width: 100%; } .calc-grid { grid-template-columns: 1fr; } } .calc-chart { margin: 1rem 0; text-align: center; } .calc-chart svg { max-width: 100%; height: auto; } .calc-chart-legend { display: flex; flex-wrap: wrap; justify-content: center; gap: 0.6rem 1.2rem; margin-top: 0.6rem; font-size: 0.8rem; color: #555; } .calc-chart-legend span { display: inline-flex; align-items: center; gap: 0.3rem; } .calc-chart-legend i { display: inline-block; width: 10px; height: 10px; border-radius: 2px; font-style: normal; } .calc-related { max-width: 640px; margin: 2rem 0 1rem; padding: 1.25rem 1.5rem; background: #f8f9fa; border: 1px solid #e8e8e8; border-radius: 8px; } .calc-related h3 { font-family: Georgia, serif; font-size: 1rem; color: #1a1a1a; margin: 0 0 0.75rem; padding-bottom: 0.4rem; border-bottom: 2px solid var(--ac, #3d5a80); } .calc-related-list { list-style: none; padding: 0; margin: 0 0 0.75rem; display: grid; grid-template-columns: 1fr 1fr; gap: 0.4rem 1.5rem; } .calc-related-list li a { font-size: 0.88rem; color: var(--ac, #3d5a80); text-decoration: none; } .calc-related-list li a:hover { text-decoration: underline; } .calc-browse-all { margin: 0.5rem 0 0; font-size: 0.9rem; font-weight: 600; } .calc-browse-all a { color: var(--ac, #3d5a80); text-decoration: none; } .calc-browse-all a:hover { text-decoration: underline; } @media (max-width: 720px) { .calc-related-list { grid-template-columns: 1fr; } }
Insulation Resistance Degradation Calculator
Estimate insulation resistance degradation over time using the Arrhenius thermal aging model and calculate the Polarization Index (PI) and Dielectric Absorption Ratio (DAR).
Initial Insulation Resistance R₀ (MΩ)
Operating Temperature T (°C)
Reference Temperature T_ref (°C)
Activation Energy Eₐ (eV) [typical: 0.5–1.2 eV]
Aging Time t (hours)
R at 1 minute (MΩ) [for PI/DAR]
R at 10 minutes (MΩ) [for PI]
R at 30 seconds (MΩ) [for DAR]
Calculate
function insCalc() { const resultDiv = document.getElementById('ins-result'); resultDiv.style.display = 'block';
// --- Parse inputs --- const R0 = parseFloat(document.getElementById('ins-r0').value); const T = parseFloat(document.getElementById('ins-temp').value); const Tref = parseFloat(document.getElementById('ins-tref').value); const Ea = parseFloat(document.getElementById('ins-ea').value); const t = parseFloat(document.getElementById('ins-time').value); const R1min = parseFloat(document.getElementById('ins-r1min').value); const R10min = parseFloat(document.getElementById('ins-r10min').value); const R30s = parseFloat(document.getElementById('ins-r30s').value);
const errors = [];
// --- Validate Arrhenius inputs --- const hasArrhenius = !isNaN(R0) || !isNaN(T) || !isNaN(Tref) || !isNaN(Ea) || !isNaN(t); let Rt = null, AF = null, degradPct = null;
if (hasArrhenius) { if (isNaN(R0) || R0 0 && R10min > 0) PI = R10min / R1min; }
if (hasDAR) { if (R30s 0 && R30s > 0) DAR = R1min / R30s; }
if (!hasArrhenius && !hasPI && !hasDAR) { errors.push("Please enter at least one set of inputs to calculate."); }
if (errors.length > 0) { resultDiv.innerHTML = 'Input Errors:' + errors.map(e => '').join('') + ''; return; }
// --- Build output --- let html = '### Results ';
// Arrhenius results if (hasArrhenius && errors.length === 0 && Rt !== null) { const afStr = AF.toExponential(4); const RtStr = Rt.toFixed(3); const degradStr = degradPct.toFixed(2);
let conditionAF = ''; if (AF > 1) conditionAF = 'Higher stress than reference (accelerated aging)'; else if (AF Lower stress than reference (decelerated aging)'; else conditionAF = 'Same as reference conditions';
html += `
ParameterValue Acceleration Factor (AF)${afStr} — ${conditionAF} Degraded Resistance R(t)${RtStr} MΩ Degradation${degradStr}% Remaining Fraction${(100 - degradPct).toFixed(2)}% `;
// Condition assessment let cond = '', condColor = ''; if (Rt >= 100) { cond = 'Excellent'; condColor = '#27ae60'; } else if (Rt >= 10) { cond = 'Good'; condColor = '#2ecc71'; } else if (Rt >= 1) { cond = 'Fair'; condColor = '#f39c12'; } else if (Rt >= 0.1) { cond = 'Poor'; condColor = '#e67e22'; } else { cond = 'Critical'; condColor = '#c0392b'; }
html += `Insulation Condition: ${cond} (IEEE 43 guideline: ≥1 MΩ minimum, ≥100 MΩ excellent for most equipment)
`; }
// PI results if (PI !== null) { let piCond = '', piColor = ''; if (PI >= 4) { piCond = 'Excellent'; piColor = '#27ae60'; } else if (PI >= 2) { piCond = 'Good'; piColor = '#2ecc71'; } else if (PI >= 1.5) { piCond = 'Questionable'; piColor = '#f39c12'; } else { piCond = 'Dangerous / Replace'; piColor = '#c0392b'; }
html += `
ParameterValue Polarization Index (PI = R₁₀ₘᵢₙ / R₁ₘᵢₙ) ${PI.toFixed(3)} — ${piCond}
IEEE 43: PI <1.5 = Dangerous, 1.5–2.0 = Questionable, 2.0–4.0 = Good, ≥4.0 = Excellent
`; }
// DAR results if (DAR !== null) { let darCond = '', darColor = ''; if (DAR >= 1.6) { darCond = 'Good'; darColor = '#27ae60'; } else if (DAR >= 1.25){ darCond = 'Questionable'; darColor = '#f39c12'; } else { darCond = 'Dangerous'; darColor = '#c0392b'; }
html += `
ParameterValue Dielectric Absorption Ratio (DAR = R₁ₘᵢₙ / R₃₀ₛ) ${DAR.toFixed(3)} — ${darCond}
IEEE 43: DAR <1.25 = Dangerous, 1.25–1.6 = Questionable, ≥1.6 = Good
`; }
resultDiv.innerHTML = html; }
#### Formulas Used
1. Arrhenius Acceleration Factor (AF):
AF = exp[ (Eₐ / k) × (1/T_ref − 1/T) ]
- Eₐ = Activation energy (eV)
- k = Boltzmann constant = 8.617 × 10⁻⁵ eV/K
- T, T_ref = Temperatures in Kelvin (°C + 273.15)
2. Degraded Resistance after time t:
R(t) = R₀ × exp[ −(t / 8760) × ln(AF) ]
- R₀ = Initial insulation resistance (MΩ)
- t = Aging time (hours); 8760 h = 1 year normalization
3. Polarization Index (PI):
PI = R(10 min) / R(1 min)
4. Dielectric Absorption Ratio (DAR):
DAR = R(1 min) / R(30 s)
#### Assumptions & References
- IEEE Std 43-2013: Recommended Practice for Testing Insulation Resistance of Electric Machinery.
- IEC 60085: Thermal evaluation and designation of electrical insulation.
- IEEE Std 930-2004: Guide for Statistical Analysis of Electrical Insulation Breakdown Data.
More Calculators
- Child Support Arrears and Interest Calculator
- TRIR (Total Recordable Incident Rate) Calculator
- Workers Compensation Premium Calculator
- Child Support Payment Calculator
- Family Childcare Affordability Calculator
- Parenting Time Credit Calculator
- Concrete Slab Cost Estimator
- South Dakota Prevailing Wage Project Cost Calculator
- Subcontractor vs Employee Cost Calculator
- Contractor License Verification Checklist Scorer
- Multiple Bid Fair Price Range Calculator
- Project Payment Schedule Calculator
Read Next
Contractor License Verification Checklist Scorer ANA › Life Services Authority › National Calculator Authority › Contractor License Verification Checklist Scorer...
Study Time Planner Authority Network America › Life Services Authority › National Calculator Authority .calc-container { max-width: 640px;...