--- title: "Power Quality Rating Simulator" url: "https://3dfs.com/technology/pqr-simulator" description: "Poor power quality carries costs that never appear on a bill. Change the load in our simulator and watch the rating and annual cost move together." updated: "2026-10-15" --- # Power Quality Rating Simulator > Poor power quality carries costs that never appear on a bill. Change the load in our simulator and watch the rating and annual cost move together. 3DFS PQR SIM ## Real-Time Waveforms, Metrics, and Economic Impact 480V 3Φ • 60Hz WAVEFORMS POWER QUALITY RATING (PQR) i 100% Excellent NEUTRAL CURRENT i 0.0A Minimal CRITICAL FAILURE RISK i +0.0% Minimal ELECTRIC SYSTEM LOSSES i 0.0% Minimal ANNUAL DOWNSTREAM COST IMPACT $0 Energy $0 ENERGY WASTE I²R conductor and distribution losses Equipment $0 EQUIPMENT Accelerated degradation and wear Downtime $0 DOWNTIME RISK Outage cost set per scenario Infrastructure $0 INFRASTRUCTURE K-rated and oversized equipment CRITICAL FACTORS SYSTEM STRENGTH i Short-Circuit Ratio Grid strength indicator n/a SCR = fault current / load current. Model bands: 20 or more is strong, 10 to 20 moderate, under 10 weak. Resiliency Score Ride-through capability n/a Model weights: PQR 30%, SCR 30%, PF 20%, THD 20%. A score of 70% or more is strong; under 40% is vulnerable. COMPLIANCE SUMMARY i Current THD Against the IEEE 519 5% row n/a Neutral Current Triplen summation limit n/a Power Factor Displacement PF ≥0.90 n/a Phase Imbalance ≤2% current imbalance n/a INDUSTRY SCENARIOS PQ MITIGATION EQUIPMENT i LIVE CONTROLS i PHASE LOAD (A) Balance: n/a L1 100 A L2 100 A L3 100 A POWER FACTOR (0-1) Avg: 1.00 L1 1.00 L2 1.00 L3 1.00 THD-I (%) Avg: 0% L1 0.0% L2 0.0% L3 0.0% HARMONIC SPECTRUM i H3 (180Hz)0% H5 (300Hz)0% H7 (420Hz)0% H9 (540Hz)0% H11 (660Hz)0% H13 (780Hz)0% PQR FORMULA: True Power Factor with Balance Factor PQR = avg(TPF) × BF × 100 where TPF = cos(φ) / [√(1+THDI²) × √(1+THDV²)] and BF = max(0, 1 – Imbalance/100) PHASE L1 P (Active Power)– Q (Reactive Power)– S = √(P² + Q²)– cos φ = P / S– THDI– DI = √(1+THDI²)– THDV– DV = √(1+THDV²)– TPFL1 = cosφ / (DI×DV)– PHASE L2 P (Active Power)– Q (Reactive Power)– S = √(P² + Q²)– cos φ = P / S– THDI– DI = √(1+THDI²)– THDV– DV = √(1+THDV²)– TPFL2 = cosφ / (DI×DV)– PHASE L3 P (Active Power)– Q (Reactive Power)– S = √(P² + Q²)– cos φ = P / S– THDI– DI = √(1+THDI²)– THDV– DV = √(1+THDV²)– TPFL3 = cosφ / (DI×DV)– FINAL CALCULATION avg(TPF) = (TPFL1+TPFL2+TPFL3)/3– Imax, Imin, Iavg– Imbalance = (Imax-Imin)/Iavg × 100– BF = max(0, 1 – Imbalance/100)– PQR = avg(TPF) × BF × 100– An educational model. Results at a real installation differ. A measurement shows them. PQR Sim v0.5.8 ## Understanding Power Quality Metrics ![Animated three-phase circuit: three sources feeding three loads, with current flowing in each phase and returning through the neutral](https://3dfs.com/wp-content/uploads/2026/08/3-phase-flow.gif) Current leaves on each phase and returns through the neutral. When the three phase currents are equal the returning current cancels at the node. When they are not, the difference comes back on the neutral. The dashboard shows seven metrics for power quality and its cost. They are numbered below in the order they appear on screen. Each card says what the value means and how the model computes it. 1 ### Power Quality Rating (PQR) One score for the whole system In plain terms: PQR is one score for how well the electricity does its work. Higher is better. A balanced load with clean sine waves at unity power factor scores the maximum. A lower score means more current for the same work, more heat and more stress on equipment. PQR combines three factors: true power factor, harmonic distortion and phase balance. The model follows the IEEE 1459-2010 definition of power factor, active power over apparent power. It estimates it from the terms below. PQR = avg(TPF) × BF × 100 TPF (True Power Factor) = cos(φ) / [√(1+THDI²) × √(1+THDV²)] cos(φ) Displacement power factor: the ratio of real power (P) to apparent power (S) at the fundamental frequency THDI, THDV Total harmonic distortion of current and voltage, as IEEE 519-2022 defines it BF (Balance Factor) = max(0, 1 − Imbalance%/100). It lowers the score when the phases carry unequal current. IEEE 1459-2010 True Power Factor | PQR score (model bands) | Rating | Meaning | | --- | --- | --- | | ≥80% | Excellent | Close to the ideal load | | 50% to 79% | Moderate | Some extra current and heat; watch the trend | | <50% | Poor | High losses and equipment stress | 2 ### Neutral Current Current in the return conductor In plain terms: In a balanced system the neutral carries almost no current, like a seesaw sitting level. Unequal phase loads and harmonic current both add to it. Triplen harmonics (3rd, 9th, 15th) do the most harm. On the neutral they add together instead of cancelling. The model combines three sources of neutral current. It adds them as a root sum of squares. Triplen currents are in phase on the three phase conductors, so on the neutral they add. A balanced load with 15% third harmonic on each phase puts 45% of the fundamental phase current on the neutral. IN = √(Iimbalance² + Itriplen² + Ivoltage²) Iimbalance Vector sum of phase currents at 120° separation Itriplen Triplen current (3rd and 9th) of the three phases, added arithmetically. Triplens are zero sequence in Fortescue’s symmetrical components. Ivoltage Additional current from voltage unbalance NEC 2023, 310.15(E)(3) White Paper 38 Rasmussen, N., “Harmonic Currents in the Data Center: A Case Study,” a leading maker’s White Paper 38 | Neutral (% of phase), model bands | Status | Action | | --- | --- | --- | | <10% | Minimal | Normal operation | | 10% to 30% | Elevated | Watch conductor temperature | | 30% to 100% | Critical | Check neutral sizing | | Above 100% | Critical | The neutral carries more than a phase | 3 ### Critical Failure Risk A thermal stress score In plain terms: This is a stress meter for equipment. A reading of 30% is not a 30% chance of failure. It is a model score from 0% to 95% that rises with heat from harmonics, low power factor and overload. The model adds four stress terms. It does not compute temperature. It scores stress from K-factor, power factor, THD and load. IEEE C57.91-2011 gives the aging equation for oil-filled transformers. Risk = K-Risk + PF-Risk + THD-Risk + Load-Risk K-Risk Harmonic heating in transformers (IEEE C57.110-2018) PF-Risk Excess current from low power factor THD-Risk Eddy current and skin effect losses Load-Risk Thermal stress from operation above rating IEEE C57.110-2018 IEEE C57.91-2011 | Risk score | Model label | Meaning | | --- | --- | --- | | <10% | Minimal | Near design conditions | | 10% to 30% | Elevated | Extra heat; watch the trend | | 30% to 50% | High | Equipment runs hot | | Above 50% | High | Sustained thermal stress | 4 ### Electric System Losses Power wasted as heat In plain terms: A wire acts like a small heater. Low power factor and harmonic current make more current flow for the same work. The model counts the extra rms current, compared with an ideal load. It does not add skin effect. Conductor losses scale with the square of current. Current rises as true power factor falls, so a small drop in power factor raises losses by more. The table shows the arithmetic at constant power and voltage. Losses% = [(1/TPF)² – 1] × 100 + Equipment_Losses TPF True Power Factor (includes harmonic distortion) Equipment_Losses Operating losses of correction equipment (if present) IEEE 1459-2010 | True PF | Current Increase | I²R Loss Increase | | --- | --- | --- | | 1.00 | Baseline | Baseline | | 0.95 | +5% | +11% | | 0.85 | +18% | +38% | | 0.75 | +33% | +78% | 5 ### Annual Downstream Cost Impact The model’s yearly estimate of what poor power quality costs In plain terms: A car with bad alignment wastes fuel (energy), wears out tires (equipment), risks a blowout (downtime) and may need special tires (infrastructure). In the data center scenario, one outage costs about two years of the model’s energy waste. The model prices that outage at $740,000. The cost has four parts. Energy waste is the easiest to see. In the model it is often not the largest part. The equipment part leads in the data center, HVAC and shipboard scenarios. | Category | What It Measures | Primary Drivers | | --- | --- | --- | | Energy | Additional electricity from losses | Low TPF, harmonic current | | Equipment | Accelerated replacement costs | K-Factor, imbalance, neutral heating | | Downtime | Yearly outage cost in the model | Outage cost set per scenario, plus loss and K-factor terms | | Infrastructure | Extra capital cost of PQ-rated equipment | K-rated transformers, oversized neutral | Outage cost per incident, as set in the model: Data center: $740,000 · Shipboard: $500,000 · Manufacturing: $260,000 · HVAC: $85,000 These are settings in the model. The Downtime Risk card below shows how it uses them. 6 ### System Strength How stiff the supply is In plain terms: This shows how stiff the supply is. A strong source (high SCR) is like a fire hydrant: it delivers plenty of water and the pressure holds. A weak source, such as a ship’s generator, is like a garden hose: open too many sprinklers and each one runs poorly. A weak source makes power quality problems worse. Short-Circuit Ratio (SCR) measures source stiffness: SCR = Isc / IL (short-circuit current over load current) THDV and THDI Each scenario sets its own voltage THD. A weak source turns the same current distortion into more voltage distortion. Resiliency Score is a weighted sum set by the model: Resiliency = 0.30×PQR + 0.30×SCR + 0.20×PF + 0.20×THD (normalized) IEEE 519-2022 Table 2 | SCR (model bands) | Strength | Resiliency | Rating | | --- | --- | --- | --- | | 50 (Ideal Baseline) | Strong | ≥70% | Strong | | 20 to 50 | Strong | 40% to 69% | Moderate | | 10 to 20 | Moderate | <40% | Vulnerable | | <10 | Weak | n/a | High risk | 7 ### Compliance Summary Four checks against published limits In plain terms: These are the speed limits of an electrical system. Going over them causes equipment damage and interference. A “Pass” means the model’s value sits inside the limit it applies. Current THD IEEE 519-2022 Table 2 Total demand distortion (TDD) limits the harmonic current a site sends back to the utility at the point of common coupling. The limit rises with the short-circuit ratio. It is 5% under 20, 8% from 20 to 50, 12% from 50 to 100, 15% from 100 to 1,000 and 20% above 1,000. The model applies the 5% row in every scenario, against the load’s current THD. Neutral Current NEC 2023, 310.15(E)(3) Neutral current must stay within the conductor’s ampacity. Where most of the load on a 4-wire wye circuit is nonlinear, the NEC counts the neutral as a current-carrying conductor when the cable is derated. Power factor IEEE 1459-2010 IEEE 1459-2010 defines power factor. It sets no minimum. The model checks displacement power factor. Its limit is 0.90 for the ideal, HVAC and manufacturing scenarios, 0.85 for the data center and microgrid, and 0.80 for shipboard. Each utility tariff sets its own limit. Below it, losses rise and less capacity is left for useful load. Phase imbalance NEMA MG 1, 14.36 The model flags current imbalance between phases above 2% for the ideal, HVAC and manufacturing scenarios, above 3% for the microgrid and shipboard, and above 10% for the data center. NEMA MG 1, clause 14.36 gives the motor derating curve for unbalanced voltage. A few percent matters, because motor heating rises faster than the unbalance. Each setting answers to different standards. Each scenario below lists the standards that apply and what the model loads into it. 1 ### Data Center / IT High-density computing loads Applicable Standards - IEEE 519-2022, Table 2: TDD of 8% or less where the short-circuit ratio is 20 to 50. The model applies 5%. - IEEE C57.110-2018: derating transformers that carry harmonic current - ASHRAE TC 9.9: thermal guidelines for data processing environments - Uptime Institute: Tier Standard for data center topology What the model shows In the model, switch-mode power supplies put current THD at 35% to 42% per phase. Single-phase supplies put triplen harmonics on the neutral. One outage costs $740,000 in the model. The source has a short-circuit ratio of 20. 2 ### HVAC / VFD Systems Variable frequency drives Applicable Standards - IEEE 519-2022, Table 2: TDD of 8% or less where the short-circuit ratio is 20 to 50. The model applies 5%. - NEMA MG 1, 14.36: motor derating for voltage unbalance - NEMA MG 1, Part 31: motors fed from drives, including shaft voltage - Model settings: a short-circuit ratio of 25 and an outage cost of $85,000 What the model shows Six-pulse drives draw 5th and 7th harmonic current. In the model, current THD is 35% to 45% per phase. Fast voltage edges from a drive can push current through motor bearings and pit them. 3 ### Microgrid / DER Distributed energy resources Applicable Standards - IEEE 1547-2018, 7.3: total rated-current distortion (TRD) of 5% or less - IEEE 1547-2018, 6.4: voltage ride-through - IEEE 1547-2018, 5.3: voltage and reactive power control, including volt-var - Utility interconnection: site-specific requirements What the model shows The model sets a short-circuit ratio of 15. It fixes THDV below 1% and does not derive it from THDI. The three phases carry unequal load. Output that keeps changing cycles the inverter capacitors. 4 ### Shipboard Power Isolated generator systems Applicable Standards - MIL-STD-1399 Section 300, Part 1 (2018), Table II: voltage harmonic distortion of 5% or less - MIL-STD-1399: average line-to-line voltage within 5% and frequency within 3% of 60 Hz - MIL-STD-461G: conducted emission limits - IEEE 45.1-2023: electrical installations on shipboard, design What the model shows In the model, current THD is 38% to 42% per phase on an isolated generator with a short-circuit ratio of 10. A source that weak lets current distortion raise THDV. Power factor is about 0.84, so the generator carries current that does no work. One outage costs $500,000 in the model. 5 ### Manufacturing Industrial production loads Applicable Standards - IEEE 519-2022, Table 2: TDD of 5% or less where the short-circuit ratio is under 20 - IEEE 141 (Red Book): power distribution for industrial plants - NEMA MG 1: motor derating curves - Utility tariffs: each sets its own power factor penalty; the model uses 0.90 What the model shows In the model, welders and thyristor drives put current THD at 35% to 45% per phase. Power factor is about 0.84, below the 0.90 the model uses for a tariff penalty. One outage costs $260,000 in the model. 6 ### Ideal Baseline Reference for comparison Target Parameters - PQR of 100: the top of the scale - THD = 0%: pure sine waves - PF = 1.0: unity power factor - Imbalance = 0%: equal current on all three phases What it is for The Ideal Baseline is a reference, not a real site. It models linear resistive loads with equal current on each phase. Comparing a scenario with it shows what each problem costs in the model. The annual cost on the dashboard adds four parts. Each part uses fixed coefficients set in the model. Real costs depend on the site. Use these estimates to rank problems, not to set a budget. 1 ### Energy Waste Additional electricity from losses Poor power quality makes more current flow for the same useful work. Conductor losses scale with I², so a small drop in power factor costs more than it looks. Energy_Cost = Base_kW × Hours × Rate × (Loss%/100) × 0.5 × Multiplier + Correction_Equipment_Losses Model settings - Base load: 1 MW at $0.12/kWh - 8,760 hours a year (continuous operation) - Diversity factor of 0.5 for load variation - Does not include demand charges The model uses one energy rate. Local tariffs differ. 2 ### Equipment Degradation Accelerated aging and replacement Heat from harmonics, imbalance and neutral overload shortens equipment life. The model charges a fixed cost per unit of K-factor, imbalance and neutral current. It does not compute temperature. IEEE C57.91-2011 gives the aging equation for oil-filled transformers. Equipment_Cost = K_Stress + Imbalance_Stress + Neutral_Stress K_Stress = max(0, K-1) × $40,000/yr Imbalance = max(0, Imb%-2) × $600/yr Neutral = max(0, N%-20) × $300/yr What the model charges - K-factor above 1: $40,000 a year per unit of K - Phase imbalance above 2%: $600 a year per percentage point - Neutral current above 20% of phase current: $300 a year per percentage point These coefficients are model settings. A site’s own repair and replacement records give a better estimate. 3 ### Downtime Risk Outage cost set per scenario The model starts from an outage cost set for each scenario. It adds terms for losses above 3% and for K-factor, then applies the scenario multiplier. It does not use the risk score. Downtime_Cost = [(Outage_Cost / $50,000) × $6,000 + max(0, Loss%-3) × $400 + max(0, K-1) × $1,500] × Multiplier Outage cost per incident in the model - Data center: $740,000 - Shipboard: $500,000 - Manufacturing: $260,000 - HVAC: $85,000; Ideal Baseline: $50,000; Microgrid: $1,477 These are settings in the model, not survey results. A site’s own outage history gives a better figure. 4 ### Infrastructure Capital equipment premiums Poor power quality calls for costlier equipment: K-rated transformers, larger neutrals and extra filters. Infrastructure = K_Transformer + Neutral_Upgrade + Base K_Transformer = max(0, K-1) × $5,000/yr (amortized) Neutral_Upgrade = max(0, N%-25) × $150/yr Base = $6,000/yr (maintenance overhead) What the model charges - K-factor above 1: $5,000 a year per unit of K, amortized - Neutral current above 25% of phase current: $150 a year per percentage point - A fixed $6,000 a year for maintenance - NEC 2023, 310.15(E)(3): on a 4-wire, 3-phase wye circuit where most of the load is nonlinear, the neutral counts as a current-carrying conductor The shipboard scenario doubles this part through its multiplier. Scenario multipliers: The same electrical problem costs more in some settings than in others. The model scales each cost part by a fixed multiplier for each scenario: Data Center: Energy 1.5×, Equipment 2.0×, Downtime 3.0×, Infrastructure 1.8× · Shipboard: Energy 1.2×, Equipment 2.0×, Downtime 4.0×, Infrastructure 2.0× · Manufacturing: Energy 1.3×, Equipment 1.4×, Downtime 1.5×, Infrastructure 1.2× · Microgrid: Energy 0.6×, Equipment 0.8×, Downtime 0.5×, Infrastructure 1.4× The multipliers are model settings, not measured results. The simulator models three kinds of correction. Each fixes some problems and can cause others. The figures below are the settings the model uses. ### Active Correction (VectorQ SDE) Our VectorQ applies Software-Defined Electricity. It measures the electricity at the panel and corrects reactive power, harmonics and phase imbalance every cycle. Its capacity is finite, as the note below shows. Q Reduction 97% THD Reduction 86% Balance Improvement 93% Operating Loss 0.4% Capacity check: The model assumes one unit rated 150 kVA. The figures above hold while the correction demand stays under 85% of that rating. Above it, the model drops to partial correction and scales it down further as demand grows. ### Passive Harmonic Filters Tuned inductor and capacitor circuits absorb set harmonic frequencies. They work well on the 5th and 7th harmonics and do little for the triplens (3rd, 9th). Their tuning is fixed, so they cannot follow a changing load. H5 Reduction 85% H7 Reduction 80% H3 Reduction 15% Model Loss Setting 10% Side effects: In the model, a filter raises phase current by 10% and lowers voltage by 2%. A filter does not correct phase imbalance. The 10% loss is a model setting, not a measured rate. ### Capacitor Banks Switched capacitor banks are the traditional fix for power factor. They correct displacement power factor but not harmonics. They can also form a resonance with the source. The 9% loss is a model setting, not a measured rate. Q Reduction 60% PF Correction Displacement only H5 Amplification 1.8× Model Loss Setting 9% Resonance risk: IEEE 1036-2020 is the application guide for shunt capacitors rated 2,400 V and above. It covers the harmonic study to run before a bank goes in. The bank and the source resonate near fr = f1 × √(Ssc/Qcap). If fr lands near the 5th or 7th harmonic, the bank amplifies that harmonic and can fail. This simulator estimates a rating from the figures entered above. To have a real instrument recording analyzed, see [Power Quality Risk Analysis](https://3dfs.com/technology/pqra).