I. Introduction: Extra Thick Insulation Enameled Wire – The “Insulation Peak” of Ultra-High Voltage Applications
Extra Thick Insulation Enameled Copper Wire (ETI-ECW) is the core insulation for Ultra High Voltage (UHV) electrical equipment. Its insulation thickness is 3-10 times of ordinary enameled wire, and it is specially designed for 110-1,000 kV ultra-high voltage transformers, reactors, transformers, casing and other key equipment.
Ultra-thick insulation vs. normal insulation :
– Normal enameled wire: Grade 1 (8-15 μm) vs ultra-thick Grade 4 (30-50 μm +)
– Thickness difference: 3-10x
– Breakdown voltage: standard 5 kV vs very thick > 20 kV
– Applicable voltage: Low voltage vs UHV (110-1,000 kV)
5 core applications :
– UHV transformer (500-1,000 kV)
– UHV reactor
– UHV transformer (PT/CT)
– UHV sleeve
– Test transformer (> 1,000 kV)
4 Core Requirements :
– Ultra-thick insulation : film thickness 30-100 μm
– Ultra-high dielectric : BDV > 20-50 kV
– Ultra-low loss : tan δ < 0.005
– Extra long life : 40-60 years
1.1 Birth of ultra-thick insulated enameled wire
3 stages of development :
– 1950s: standard enameled wire (Grade 1-2)
– 1980s: Thick insulated enameled wire (Grade 3)
– 2000s to present: ultra-thick insulated enameled wire (Grade 4 +)
1.2 6 Core Strengths
1.3 Top 5 Application Areas
II. Enamel Material System for Extra Thick Insulation Enameled Wire
2.1 Polyimide (PI) paint film
Chemical composition :
– Polyimide resin
– Aromatic structure
– Extremely high thermal stability
– Nitrogen-containing polymers
Features :
– Film thickness: 30-100 μm
– Dielectric strength: > 25 kV
– Temperature rating: Class C (> 220°C)
– Media loss: < 0.005
Benefits :
– Extremely high temperature resistance
– Very high dielectric
– Excellent chemical stability
– Extremely long life (60 + years)
Limitations :
– High cost
– Complex workmanship
– Crispy paint film
– Difficult to repair
Typical applications :
– UHV transformer
– Nuclear Power Units
– Aviation Military
– Test transformer
2.2 Polyamideimide (Pai) paint film
Chemical composition :
– Polyamideimide
– Mixed structure of amide + imide
– Balance flexibility with heat resistance
Features :
– Film thickness: 30-80 μm
– Dielectric strength: > 22 kV
– Temperature rating: H-N (180-200°C)
– Media loss: < 0.008
Benefits :
– High temperature resistance + high dielectric
– Paint film is more flexible than PI
– Better processability than PI
– Cost is lower than PI
Typical applications :
– High-end motor windings
– Traction motor
– Industrial motors
– UHV transformer
2.3 Polyesterimide (PEI) paint film
Chemical composition :
– Polyesterimine
-Ester + imide structure
– Balanced performance
Features :
– Film thickness: 30-70 μm
– Dielectric strength: > 20 kV
– Temperature rating: F-H (155-180°C)
– Media loss: < 0.01
Benefits :
– Good craftsmanship
– Moderate cost
– Balanced performance
– Suitable for large volumes
Typical applications :
– General-purpose high-voltage motors
– High voltage transformer
– Generic reactor
– Universal transformer
2.4 Composite film (PI + Pai/PEI + Pai)
Structure :
– Interior: PI or PEI (High Temperature Resistance)
– Middle layer: adhesive layer
– Outer layer: Pai (high strength)
Features :
– Film thickness: 40-100 μm
– Dielectric strength: > 25 kV
– Temperature rating: H-C (180-220°C)
– Media loss: < 0.005
Benefits :
– Performance Composite
– Multifaceted
– Suitable for high-end applications
2.5 5 major paint film materials control
| Paint Film | Thickness | BDV | Heat Resistance | Dielectric Loss | Main Applications |
|---|---|---|---|---|---|
| PI | 30-100 μm | > 25 kV | C (220°C +) | < 0.005 | UHV Transformer |
| Pai | 30-80 μm | > 22 kV | H-N (180-200°C) | < 0.008 | High-End Motor |
| PEI | 30-70 μm | > 20 kV | F-H (155-180°C) | < 0.01 | Universal High Voltage |
| PI + Pai | 40-100 μm | > 25 kV | H-C (180-220°C) | < 0.005 | UHV Equipment |
| PEI + Pai | 40-80 μm | > 22 kV | H-N (180-200°C) | < 0.008 | High-end Universal |
III. Key Technical Parameters of Extra Thick Insulation Enameled Wire
3.1 Conductor Specifications
Conductor material :
– Soft copper (T1/T2/TU1/TU2)
– High strength soft copper (CuAg/CuCrZr)
– Silver and copper alloys
Conductor diameter :
– Circular line: Φ 0.5-5.0 mm
– Flat wire: 1-5 × 3-15 mm
– Coated copper wire: Φ 0.5-4.0 mm
Conductor requirements :
– High purity copper (> 99.95%)
– Low oxygen content
– High conductivity (> 100% IACS)
– High elongation (> 30%)
3.2 Paint film thickness
Film Grade :
– Grade 1 (standard): 8-15 μm
– Grade 2 (thick): 12-20 μm
– Grade 3 (thick): 18-25 μm
– Grade 4 (extra thick): 30-50 μm
– Grade 5 (super thick): 50-100 μm
Extra thick paint film options :
– 110 kV: Grade 4 (30-50 μm)
– 220 kV: Grade 4-5 (40-60 μm)
– 500 kV: Grade 5 (50-80 μm)
– 1,000 kV: Grade 5 (70-100 μm)
Paint film uniformity :
– Radial: ± 2 μm
– Axial: ± 3 μm
– Ovality: < 5%
3.3 Dielectric properties
Dielectric Strength (BDV) :
– Grade 4: > 20 kV
– Grade 5: > 30 kV
– For UHV: > 50 kV
Volume resistivity :
– Normal: > 10 ¹ ₽ Ω · cm
– After humid heat: > 10 ¹ ³ Ω · cm
Media loss :
– 1 kHz: < 0.005
– 100 kHz: < 0.008
– 1 MHz: < 0.01
Dielectric constant :
– 50 Hz: 3.5-4.5
– 1 kHz: 3.2-4.0
3.4 Thermal performance
Temperature rating :
– PI: Class C (> 220°C)
– Pai: H-N class (180-200°C)
– PEI: Class F-H (155-180°C)
– Composite: H-C class
Softening breakdown temperature :
– PI: > 400°C
– Pai: > 350°C
– PEI: > 300°C
Thermal aging :
– Arrhenius model
– 220°C lifetime: > 20,000h
– 180°C lifetime: > 50,000 h
– 155°C Life: > 100,000h
3.5 Mechanical properties
Elongation :
– Soft copper: > 30% (Φ < 1.0 mm)
– Soft copper: > 25% (Φ ≥ 1.0 mm)
– Film: > 10%
Tensile strength :
– Soft copper: > 200 MPa
– High strength copper: > 220 MPa
Paint film adhesion :
– Quick pull: no shedding
– Winding: 1x diameter without cracking
Bending resistance :
– Round rod winding: 1-2x
– Paint film does not crack
IV. Application Areas of Extra Thick Insulation Enameled Wire
4.1 UHV Transformer
Application : 500-1,000 kV UHV transformer
Features :
– Voltage: 500-1,000 kV
– Capacity: 500-1,500 MVA
– Lifespan: 40-60 years
– Reliability: > 99.99%
Enameled wire requirements :
– Film thickness: 50-100 μm
– Dielectric strength: > 30-50 kV
– Media loss: < 0.005
– Paint film type: PI or PI + Pai
Application site :
– High voltage windings
– Tangled windings
– Shielded winding
– Electrostatic plate
4.2 UHV Reactor
Application : 110-1,000 kV shunt reactor
Features :
– Voltage: 110-1,000 kV
– Capacity: 10-200 Mvar
– Lifespan: 40-60 years
Enameled wire requirements :
– Film thickness: 40-80 μm
– Dielectric strength: > 25 kV
– Paint film type: PI or Pai
4.3 UHV Transformer
Application : Voltage Transformer (PT)/Current Transformer (CT)
Features :
– Voltage: 110-1,000 kV
– Accuracy: 0.2-0.5 level
– Lifespan: 40-60 years
Enameled wire requirements :
– Film thickness: 30-60 μm
– Dielectric strength: > 20 kV
– Paint film type: PI or Pai
– Media loss: < 0.005
4.4 UHV sleeves
Application : UHV casing (oil immersion/SF6)
Features :
– Voltage: 110-1,000 kV
– Current: > 2,000 A
– Lifespan: 40-60 years
Enameled wire requirements: – Film thickness: 40-80 μm – Dielectric strength: > 25 kV – Coating type: PI or PEI+PAI
4.5 Summary of the Top 5 Application Areas
| Application | Voltage | Capacity | Film Thickness | Film Type |
|---|---|---|---|---|
| UHV Transformer | 500-1,000 kV | > 500 MVA | 50-100 μm | PI |
| UHV Reactor | 110-1,000 kV | 10-200 Mvar | 40-80 μm | PI/Pai |
| UHV Transformer | 110-1,000 kV | – | 30-60 μm | PI/Pai |
| UHV Sleeves | 110-1,000 kV | – | 40-80 μm | PI/PEI + Pai |
| Test transformer | > 1,000 kV | < 5 MVA | 50-100 μm | PI |
V. Insulation Design of Extra Thick Insulation Enameled Wire
5.1 Insulation structure
5-layer insulation :
– Conductor
– Interior paint film (insulation priming)
– Intermediate paint film (main insulation)
– Outer paint film (protective insulation)
– Surface treatment layer (lubrication/antifouling)
Insulation thickness distribution :
– 110 kV: 30-50 μm
– 220 kV: 40-60 μm
– 500 kV: 50-80 μm
– 1,000 kV: 70-100 μm
5.2 Dielectric strength design
BDV design formula :
V_bd ≥ k × V_working × n
Where:
V_bd = Design breakdown voltage (kV)
k = safety factor (2-3)
V_working = Operating voltage (kV)
n = Voltage waveform coefficient
Examples :
– 1,000 kV UHV transformer
-k = 2.5
– V_bd ≥ 2.5 × 1,000 = 2,500 kV
– Single enameled wire: > 50 kV
– Multilayer combination: > 2,500 kV
5.3 Media Loss Design
Design principles :
– Lower tan δ is better
– Frequency 1 kHz: < 0.005
– Frequency 50 Hz: < 0.003
– After aging: < 0.01
Control method :
– Selection of paint film material (lowest PI)
– Paint film curing process
– Moisture content control
– Impurity control
5.4 Partial discharge control
PD Design :
– Starting voltage: > 1.5x operating voltage
– Off Voltage: > 1.2x Operating Voltage
– PD intensity: < 10 pC
Control method :
– Uniformity of the paint film
– Conductor surface finish
– No impurities/air gap
– Impregnation process
VI. Production Process of Extra Thick Insulation Enameled Wire
6.1 8 Big Production Keys
- Conductor pretreatment :
- Brushed annealing
- Surface cleaning
Polishing
Preparation of lacquer :
- PI paint: solid content 15-25%
- Pai paint: 20-30% solids
Viscosity control: 50-200 cp
Painting process :
- Mold painting (preferred)
- Repeat painting (8-20 times)
- Painting speed: 5-30 m/min
Paint film overlay: 3-5 μm per layer
Baking and curing :
- Temperature gradient: 200-450°C
- Baking times: 8-20 times
- Baking time: 10-30 s/time
Nitrogen protection (PI required)
Paint film thickness control :
- Online Thickness Measurement: Laser Thickness Gauge
- Film uniformity: ± 2 μm
Ovality: < 5%
Paint film continuity :
- Saltwater bath test (7 kV)
Number of defects: 0/30 m
Take-up process :
- Tension: 5-30 N
- Rows: neat
Reel: Dedicated
Finished product inspection :
- Paint film thickness
- Dielectric strength
- Dielectric loss
- Paint film continuity
6.2 6 Process Challenges
Challenge 1: Film thickness + uniformity :
– Repeated painting
– Paint film overlay control
– Ovality control
Challenge 2: PI Paint Film Curing :
– High temperature baking (> 400°C)
– Nitrogen protection
-Imidized complete
Challenge 3: Paint film adhesion :
– Conductor surface treatment
– Lacquer formula
– Baking curve
Challenge 4: Media Loss :
– Material purity
– Baking degree
– Impurity control
Challenge 5: Paint film continuity :
– Painting quality
– Conductor surface
– Environmental control
Challenge 6: Cost Control :
– Material cost
– Process costs
– Equipment investment
VII. Quality Control of Extra Thick Insulation Enameled Wire
7.1 6 mandatory inspection items
- Film thickness :
- Thickness gauge
- Sampling: 0.1-1%
Qualified: Grade 4-5
Dielectric strength :
- High Pressure Testing
- Sampling: 0.1%
Qualified: > 20-50 kV
Paint film continuity :
- Saltwater bath + 7 kV
- Sampling: 100%
Qualified: 0 defects/30 m
Media loss :
- Mediastinometer
- Sampling: 0.1%
Qualified: tan δ < 0.005
Paint film adhesion :
- Quick pull test
- Sampling: 0.1%
Qualified: No detachment
Softening breakdown :
- Softening point test
- Sampling: 0.1%
- Qualified: > 350°C
7.2 6 Major Reliability Tests
- Aging test :
- Temperature: 180-220°C
- Time: 1,000-5,000 h
Arrhenius model
Damp heat test :
-40°C/95% RHTime: 96-1,000 h
Temperature cycle :
-40°C ↔ +85°CNumber of cycles: 100-1,000
Lightning Shock :
- 1.2/50 μs wave
- Peak: > Designed value
Multiple shocks
Operational shock :
- 250/2500 μs waves
High voltage transformer
PD Test :
- PD start voltage
- PD off voltage
- PD intensity
7.3 5 Major Quality Grades
| Level | Defect Rate | Apply |
|---|---|---|
| AAAA | < 0.01% | 1,000 kV UHV |
| AAA | < 0.1% | 500 kV UHV |
| AA | < 0.5% | 220 kV HV |
| A | < 1% | 110 kV High Voltage |
| B | < 2% | MV |
VIII. Extra Thick Insulation Enameled Wire vs Ordinary Enameled Wire
8.1 6 Dimensions Comparison
| Dimensions | Plain Enameled | Extra Thick Enameled | Differences |
|---|---|---|---|
| Film thickness | 8-15 μm | 30-100 μm | 3-10x |
| Dielectric Strength | > 5 kV | > 20-50 kV | 4-10x |
| Temperature rating | B-F (130-155°C) | H-C (180-220°C) | +50-100°C |
| Media loss | < 0.05 | < 0.005 | 10x |
| Lifetime | 20-30 years | 40-60 years | 1.5-2x |
| Cost | 1.0x | 3-10x | 3-10x |
8.2 Comparison of the Top 5 Application Scenarios
Scenario 1: 110 kV transformer
– Normal enameled wire: requires multiple layers
– Extra thick enameled wire: single
– Strengths: Single-layer construction
Scenario 2: 500 kV UHV transformer
– Normal enameled wire: 10 + layers required
– Extra thick enameled wire: 2-3 layers
– Strengths: Significantly simplified
Scenario 3: 1,000 kV UHV transformer
– Plain enameled wire: not enough
– Extra thick enameled wire: must be used
– Strengths: The only option
Scenario 4: Nuclear Power Class 1E Transformer
– Normal enameled wire: 3-5 layers required
– Extra thick enameled wire: single
– Advantages: Radiation resistance
Scenario 5: Air Military
– Plain enameled wire: limit
– Extra thick enameled wire: must
– Strengths: Extreme environments
IX. Selection Guide for Extra Thick Insulation Enameled Wire
9.1 6 Major Selection Dimensions
| Dimensions | Key Issues |
|---|---|
| Voltage class | 110 kV/220 kV/500 kV/1,000 kV |
| Application Type | Transformers/Reactors/Transformers/Sleeves |
| Temperature level | H/N/C |
| Reliability | AA/AAA/AAAA |
| Life Requirements | 30/40/60 years |
| Cost Budget | Medium/High/Very High |
9.2 6 Choice Recommendations
Application 1: 110 kV transformer
– Recommended: PEI Grade 4
– Film thickness: 30-50 μm
– BDV: > 20 kV
– Cost: Medium
Application 2: 220 kV transformer
– Recommended: PEI + Pai Grade 4-5
– Film thickness: 40-60 μm
– BDV: > 25 kV
– Cost: Medium – High
Application 3: 500 kV UHV transformer
– Recommended: PI Grade 5
– Film thickness: 50-80 μm
– BDV: > 35 kV
– Cost: High
Application 4: 1,000 kV UHV transformer
– Recommended: PI Grade 5 + (Multilayer)
– Film thickness: 70-100 μm
– BDV: > 50 kV
– Cost: Extremely high
Application 5: Nuclear Class 1E transformer
– Recommended: PI Grade 5
– Film thickness: 50-80 μm
– Radiation resistance: > 100 kGy
– Lifespan: 60 years
Application 6: Air Military
– Recommended: PI Grade 5 +
– Film thickness: 60-100 μm
– Resistant to extreme environments
– Cost: Extremely high
9.3 Selection Decision Tree
Determine voltage level
↓
110 kV → PEI Grade 4
↓
220 kV → PEI + Pai Grade 4-5
↓
500kV → PI Grade 5
↓
1,000 kV → PI Grade 5 + Multilayer
↓
Determine app type
↓
Transformers/Reactors/Transformers/Sleeves
↓
Select Paint Film System
↓
Select Vendor
X. Development Trends of Extra Thick Insulation Enameled Wire
10.1 5 Technology Trends
Trend 1: thicker paint film
– Current: 100 μm
– Target: 150-200 μm
– Application: 1,000 kV + UHV
Trend 2: Lower Media Loss
– Current: tan δ < 0.005
– Target: tan δ < 0.002
– Application: Low loss UHV
Trend 3: Higher temperature resistance
– Current: Class C (220°C +)
– Target: > 240°C
– Application: Ultra-High Temperature UHV
Trend 4: Longer life
– Current: 60 years
– Target: 80-100 years
– Application: Extra long life UHV
Trend 5: Eco-friendly paint film
– Current: solvent-based
– Target: Solvent-free
– Purpose: Eco-friendly
10.2 4 Emerging Applications
Application 1: 1,000 kV + UHV
– Paint film: 100-200 μm
– BDV: > 50 kV
– Lifespan: 60 + years
Application 2: HVDC 1,000 kV +
– Paint film: 80-150 μm
– DC resistance: low dielectric loss
– Lifespan: 60 years
Application 3: nuclear fusion
– Paint film: 100-200 μm
– Radiation resistance: > 1,000 kGy
– Lifespan: 60 + years
Application 4: Space Solar
– Paint film: 80-150 μm
– Anti-radiation + anti-vacuum
– Lifespan: 30 + years
10.3 3 major industry directions
Direction 1: Intelligent Production
– Digital Workshop
– Online monitoring
– AI Optimization
Direction 2: Localization
– Regional supply
– Reduced logistics
– Improve responsiveness
Direction 3: Sustainability
– Eco-friendly paint film
– Recycling
– Carbon neutral
XI. Common Problems and Solutions of Extra Thick Insulation Enameled Wire
11.1 6 Frequently Asked Questions
Issue 1: Insufficient film thickness
– Reason: Insufficient number of paints/low paint concentration
– Resolve: Increase the number of paints/adjust the paint
Question 2: BDV not up to standard
– Cause: Paint film impurities/high moisture content
– Solution: Increase curing temperature/increase drying time
Issue 3: High Media Loss
– Cause: incomplete curing/impurities
– Solution: Optimize baking curve/improve purity
Question 4: Poor film continuity
– Cause: paint defect/conductor surface
– Solution: Improved painted/polished conductors
Question 5: Poor film adhesion
– Cause: conductor surface/paint film curing
– Solution: Surface treatment/optimized baking
Question 6: Uneven paint film
– Reason: paint workmanship/ellipticity
– Solve: Optimize Molds/Improve Processes
11.2 5 Precautions
Action 1: Incoming Inspection
– Conductor quality + lacquer quality
– Batch sampling
– Unqualified Quarantine
Action 2: Process monitoring
– Temperature + Speed + Tension
– Real-time alarms
– Data recording
Measure 3: Equipment Maintenance
– Molds are replaced regularly
– Oven calibration
– Thickness gauge calibration
Action 4: Environmental control
– Cleanliness: Class 100,000
– Temperature: 22-28°C
– Humidity: 40-60%
Measure 5: Personnel Training
– Operating Specifications
– Exception handling
– Continuous improvement
XII. 20 Glossary of Terms
| Chinese | English | Abbreviations | Definitions |
|---|---|---|---|
| Ultra Thick Insulation | Extra Thick Insulation | ETI | Paint Film Thickness 30-100 μm Insulation |
| Ultra High Voltage | UHV | 500-1,000 kV voltage class | |
| Enameled Copper Wire | ECW | Film-insulated copper wire | |
| Film Thickness | Enamel Thickness | – | Film Thickness |
| Film Grade | Grade | – | Film Thickness Grade |
| Dielectric Strength | Dielectric Strength | BDV | Ability of the film to withstand voltage |
| Dielectric Loss | tan δ | Dielectric Loss in AC Field | |
| Partial Discharge | PD | Discharge caused by excessive local electric field | |
| Polyimide | Polyimide | PI | Very High Temperature Resistant Paint Film |
| Polyamide-imide | Polyamide-imide | Pai | High Temperature Resistant Paint Film |
| Polyesterimide | PEI | High Temperature Resistant Film | |
| Volume Resistivity | Volume Resistivity | – | Paint Film Resistivity |
| Softening Breakdown | – | Softening Breakdown | |
| Lightning Impulse | LI | Analog Lightning Impulse Voltage | |
| Operating Impulse | Switching Impulse | SI | Impulse voltage to simulate switch action |
| Transformer | – | Electrical Equipment to Change Voltage | |
| Reactor | – | Current Limiting/Compensating Electrical Equipment | |
| Transformer | Instrument Transformer | PT/CT | Measured/Protected Transformer |
| Bushing | – | Insulation of conductors through metal partitions | |
| Arrhenius | – | Temperature-life aging model |
XIII. LP Winding Wire Company Introduction
LP Winding Wire is the world’s leading manufacturer of winding wires. Its main products include enameled wires, paper coated wires, glass fiber coated wires, Nomex paper coated wires, PI film coated wires and other series.
Ultra-thick insulated enameled wire products :
Circular line series (Φ 0.5-5.0 mm) :
– PI super thick enameled wire :
– Φ 0.5-4.0 mm
– Film thickness: 30-100 μm
– BDV: > 25-50 kV
– Applicable temperature class: Class C (> 220°C)
– Pai super thick enameled wire :
– Φ 0.5-4.0 mm
– Film thickness: 30-80 μm
– BDV: > 22-40 kV
– Applicable temperature class: H-N class (180-200°C)
– PEI super thick enameled wire :
– Φ 0.5-5.0 mm
– Film thickness: 30-70 μm
– BDV: > 20-30 kV
– Applicable temperature class: F-H class (155-180°C)
– PI + Pai composite enameled wire :
– Φ 0.5-3.0 mm
– Film thickness: 40-100 μm
– BDV: > 25-50 kV
– Applicable temperature class: H-C class (180-220°C)
– PEI + Pai composite enameled wire :
– Φ 0.5-3.0 mm
– Film thickness: 40-80 μm
– BDV: > 22-40 kV
– Applicable temperature class: H-N class (180-200°C)
Flat wire series (1-5 × 3-15 mm) :
– PI flat wire :
– 1-5 × 3-15 mm
– Film thickness: 50-100 μm
– BDV: > 35-50 kV
– Pai Flat Wire :
– 1-5 × 3-15 mm
– Film thickness: 40-80 μm
– BDV: > 25-40 kV
Top 5 UHV Application Specific Products :
– For UHV transformers :
– PI Grade 5
– Film thickness: 50-100 μm
– BDV: > 35-50 kV
– Applicable: 500-1,000 kV UHV
– For UHV reactors :
– PI/Pai Grade 5
– Film thickness: 40-80 μm
– BDV: > 25-40 kV
– Applicable: 110-1,000 kV
– For UHV transformers :
– PI/Pai Grade 4-5
– Film thickness: 30-60 μm
– BDV: > 20-30 kV
– Applicable: PT/CT 110-1,000 kV
– For UHV sleeves :
– PI/PEI + Pai Grade 5
– Film thickness: 40-80 μm
– BDV: > 25-40 kV
– Applicable: 110-1,000 kV
– For test transformers :
– PI Grade 5 +
– Film thickness: 50-100 μm
– BDV: > 50 kV
– Applicable: > 1,000 kV
Core strengths :
– Full size ultra-thick enameled wire (Φ 0.5-5.0 mm)
– 5 major paint film systems (PI/Pai/PEI/PI + Pai/PEI + Pai)
– Full UHV voltage rating (110-1,000 kV)
– Ultra-high dielectric strength (> 50 kV)
– Ultra-low dielectric loss (< 0.005)
– Extra long life (40-60 years)
– UL, VDE, TÜV, CCC, CSA, Keri fully certified
– IEC 60851/GB 6109/IEEE standard
– UHV Engineering Certification
– Annual capacity of 50,000 tons
Contact :
– Official Website : https://www.lpwindingwire.com
– Email : sales@lpwindingwire.com
XIV. Summary and Outlook
Ultra-thick insulated enameled wire is the core insulation material of UHV electrical equipment – 50-100 μm ultra-thick paint film, > 50 kV dielectric strength, 40-60 years life, and is the only option for UHV transformers, reactors, transformers, and casing.
14.1 4 Core Strengths
| Strengths | Quantitative Data |
|---|---|
| Film thickness | 30-100 μm (normal 3-10 times) |
| Dielectric Strength | > 20-50 kV (Normal 4-10x) |
| Media Loss | < 0.005 (Normal 10x) |
| Lifespan | 40-60 years (1.5-2x typical) |
14.2 5 Future Trends
- Thicker paint film : 100-200 μm
- Lower dielectric loss : tan δ < 0.002
- Higher temperature resistance : > 240°C
- Longer life : 80-100 years
- Eco-friendly paint film : Solvent-free
14.3 6 Tips for Action
- Specify voltage level : 110/220/500/1,000 kV
- Specify application type : transformer/reactor/transformer/sleeve
- Select coating system : PI/Pai/PEI/composite
- Choose film thickness : Grade 4-5
- Selection of qualified suppliers : UL/TÜV/CSA
- Strict quality control : 6 mandatory inspections + 6 reliability
14.4 6 Application Areas Final Recommendation
| Application | Film Type | Film Thickness | BDV | Lifetime |
|---|---|---|---|---|
| 110 kV | PEI Grade 4 | 30-50 μm | > 20 kV | 30-40 years |
| 220 kV | PEI + Pai Grade 4-5 | 40-60 μm | > 25 kV | 30-40 years |
| 500 kV | PI Grade 5 | 50-80 μm | > 35 kV | 40-60 years |
| 1,000 kV | PI Grade 5 + Multilayer | 70-100 μm | > 50 kV | 60 years + |
| Nuclear 1E | PI Grade 5 | 50-80 μm | > 35 kV | 60 years |
| Aeromilitary | PI Grade 5 + | 60-100 μm | > 50 kV | 30-60 years |
14.5 4 emerging application directions
- 1,000 kV + UHV AC
- 1,000 kV + HVDC DC
- Nuclear Fusion (> 1,000 kGy Radiation Resistance)
- Space Solar (Radiation + Vacuum)
LP Winding Wire is committed to providing ultra-thick insulated enameled wire full-scene solutions – from 110 kV to 1,000 kV UHV, from onshore to offshore to space, from civil to nuclear to aviation military, providing the strongest insulation barrier for UHV power grids and UHV equipment worldwide.
XV. Appendix A: Quick Selection Reference for 6 Major Voltage Levels
| Voltage Grade | Recommended Paint Film | Paint Film Thickness | BDV | Lifetime | Main Applications |
|---|---|---|---|---|---|
| 35 kV | PEI Grade 3 | 18-25 μm | > 12 kV | 30 years | Medium voltage transformer |
| 110 kV | PEI Grade 4 | 30-50 μm | > 20 kV | 30-40 years | Transmission Transformer |
| 220 kV | PEI + Pai Grade 4-5 | 40-60 μm | > 25 kV | 30-40 years | Mainnet Transformer |
| 330 kV | Pai Grade 5 | 50-70 μm | > 30 kV | 40 years | High voltage transformer |
| 500 kV | PI Grade 5 | 50-80 μm | > 35 kV | 40-60 years | UHV Transformer |
| 1,000 kV | PI Grade 5 + Multilayer | 70-100 μm | > 50 kV | 60 years + | UHV |
XVI. Appendix B: 4 Major UHV Engineering Cases
B.1 Case 1: 1,000 kV UHV transmission project
Application : 1,000 kV UHV transformer
Capacity : 1,000-1,500 MVA
Enamelled wire : PI Grade 5 +
Film thickness : 70-100 μm
BDV : > 50 kV
Lifespan : 60 + years
Status : 5 + years in operation, 0 failure rate
Features : Ultra-low dielectric loss, high reliability
B.2 Case 2: 800 kV UHV DC
Application : 800 kV HVDC converter transformer
Capacity : 500-1,000 MVA
Enamelled wire : PI Grade 5
Film thickness : 60-80 μm
BDV : > 40 kV
Lifespan : 50-60 years
Status : 8 + years in operation
Features : DC resistant, low dielectric loss
B.3 Case 3: 500 kV UHV nuclear power
Application : Nuclear power Class 1E main transformer
Capacity : 500-1,000 MVA
Enamelled wire : PI Grade 5 (Radiation resistant)
Film thickness : 50-80 μm
BDV : > 35 kV
Lifespan : 60 years
Status : 10 + years in operation
Features : Radiation resistant, highly reliable
B.4 Case 4: 1,200 kV test transformer
Application : High Voltage Test Station
Capacity : 1-5 MVA
Enamelled wire : PI Grade 5 + (multilayer)
Film thickness : 80-100 μm
BDV : > 50 kV
Lifespan : 40 years
Status : Continuous operation
Features : Ultra-high voltage, intermittent operation
XVII. Appendix C: 5 Major Enamel Material Performance Comparison
| Paint Film | Upper Thickness Limit | Upper BDV Limit | Heat Resistance | Medium Loss | Cost |
|---|---|---|---|---|---|
| PI | 100 μm | 50 kV | 220°C + | < 0.005 | Very High |
| Pai | 80 μm | 40 kV | 200°C | < 0.008 | High |
| PEI | 70 μm | 30 kV | 180°C | < 0.01 | Medium |
| PI + Pai | 100 μm | 50 kV | 220°C | < 0.005 | Very High |
| PEI + Pai | 80 μm | 40 kV | 200°C | < 0.008 | High |
XVIII. Appendix D: 5 Major Supplier Evaluation Dimensions
| Dimension | Weight | Key Review Points |
|---|---|---|
| Quality Stability | 35% | Batch Consistency, CPK Value |
| UHV Performance | 25% | Engineering Cases, UHV Certification |
| Technical Capability | 20% | Film Formulation, Processing |
| Delivery Capacity | 10% | Capacity, Lead Time |
| Price | 10% | Total cost |
XIX. Appendix E: 5 Major Future Technology Directions
E.1 Direction 1: 1,500 kV UHV
- Paint film: 100-200 μm
- BDV: > 60 kV
- Lifespan: 60 + years
E.2 Direction 2: Nuclear Fusion Reactor
- Paint film: 100-200 μm
- Radiation resistance: > 1,000 kGy
- Lifespan: 60 + years
E.3 Direction 3: HVDC 1,000 kV +
- Paint film: 80-150 μm
- DC resistance: low dielectric loss
- Lifespan: 60 years
E.4 Direction 4: Space Solar
- Paint film: 80-150 μm
- Anti-radiation + anti-vacuum
- Lifespan: 30 + years
E.5 Direction 5: Superconducting transformer
- Paint film: 60-120 μm
- Cryogenic compatible
- Lifespan: 40 + years
XX. Appendix F: 8 Major International Standards
| Standard | Scope | Key Requirements |
|---|---|---|
| IEC 60851 | Enameled Wire Testing | BDV, Dielectric Loss, Adhesion |
| IEC 60317 | Enameled wire model | Specifications, performance |
| GB 6109 | Chinese GB | Equivalent to IEC 60317 |
| IEEE 57.12.00 | Power Transformers | UHV Applications |
| IEEE 4 | High Voltage Testing | 1,000 kV + Testing |
| ASTM D3032 | Enameled Wire Testing | Dielectric, Adhesion |
| UL 1441 | Enameled wire | Safety certification |
| VDE0532 | German Standard | Transformers |
XXI. Appendix G: 4 Major Design Calculation Formulas
G.1 BDV Design Formula
V_bd = k × V_working × n_safety
Where:
– V_bd = Design breakdown voltage
– k = voltage waveform coefficient (1.0-1.4)
– V_working = Operating voltage
– n_safety = safety factor (2-3)
G.2 Paint film thickness formula
d_enamel = V_bd/E_allowance
Where:
– d_enamel = film thickness
– V_bd = Design breakdown voltage
– E_allowance = Design Dielectric Strength (kV/μm)
G.3 Media Loss Formula
P_d = V ² × ω × C × tanδ
Where:
-P_d = dielectric loss
– V = Voltage
– ω = angular frequency
– C = Capacitor
– tan δ = loss factor
G.4 Lifetime formula (Arrhenius)
L (T) = L_0 × exp (E_a/k × (1/T - 1/T_0))
Where:
– L (T) = lifetime at temperature T
– L_0 = reference life
– E_a = activation energy
– k = Boltzmann constant
– T = Operating Temperature (K)
XXII. Appendix H: 5 Major Common Problems Detailed
H.1 The relationship between the thickness of the paint film and the voltage
- 35 kV: 18-25 μm (Grade 3)
- 110 kV: 30-50 μm (Grade 4)
- 220 kV: 40-60 μm (Grade 4-5)
- 500 kV: 50-80 μm (Grade 5)
- 1,000 kV: 70-100 μm (Grade 5 + Multilayer)
H.2 Paint film selection principles
- 110 kV: PEI (cost-performance balance)
- 220 kV: PEI + Pai (performance + cost)
- 500 kV: PI (high performance)
- 1,000 kV: PI multilayer (required)
H.3 BDV Design Margin
- Standard: 2.0-2.5x operating voltage
- Strict: 2.5-3.0x operating voltage
- Extreme: > 3.0x operating voltage
H.4 Media Loss Control
- Paint film material: lowest PI
- Degree of cure: fully imidized
- Moisture content: < 0.1%
- Impurity control: < 10 ppm
H.5 Life Assessment
- Accelerated aging: Arrhenius model
- Acceleration factor: 10-50
- Actual life: 40-60 years
XXIII. Appendix I: 6 Major Enamel Grades and Thickness Comparison
| Grade | Thickness (μm) | BDV (kV) | Applicable Voltage | Main Applications |
|---|---|---|---|---|
| Grade 0 | 5-10 | > 3 | < 1 kV | Low Voltage |
| Grade 1 | 8-15 | > 5 | < 1 kV | Generic |
| Grade 2 | 12-20 | > 7 | < 10 kV | MV |
| Grade 3 | 18-25 | > 12 | 10-35 kV | High Voltage |
| Grade 4 | 30-50 | > 20 | 110-220 kV | UHV |
| Grade 5 | 50-100 | > 35 | 500-1,000 kV | UHV |
XXIV. Appendix J: 6 Major Enamels Pros and Cons Comparison
J.1 PI (polyimide)
Benefits :
– Maximum temperature resistance (> 220°C)
– Maximum dielectric (> 50 kV)
– Chemically stable
– Longest lifespan
Cons :
– Highest cost
– Hardest workmanship
– Crispy paint film
– Difficult to repair
J.2 Pai (polyamide imide)
Benefits :
– High temperature resistance (200°C)
– Dielectric height (> 40 kV)
– Better flexibility than PI
– Cost is lower than PI
Cons :
– Higher costs
– Complex workmanship
J.3 PEI
Benefits :
– Moderate cost
– Good craftsmanship
– Balanced performance
– Suitable for large volumes
Cons :
– Temperature lower than PI/Pai
– Dielectric lower than PI/Pai
J.4 PI + Pai Composite
Benefits :
– Performance Composite
– Balance PI dielectric + Pai strength
– Suitable for high-end
Cons :
– Extremely expensive
– Complex workmanship
J.5 PEI + Pai Composite
Benefits :
– Performance Composite
– Cost lower than PI + Pai
– Good craftsmanship
Cons :
– Costs are still high
– Poor performance PI + Pai
J.6 PU (polyurethane, solderable)
Benefits :
– Weldable
– Low cost
– Simple process
Cons :
– Low temperature resistance (Class B 130°C)
– Low dielectric
– Not suitable for UHV
XXV. Appendix K: 5 Major Enameled Wire Cost Comparison
| Paint Film | Relative Cost | Main Reasons | Applicable Scenarios |
|---|---|---|---|
| PU | 1.0x | Simple process | Universal Low Voltage |
| PEI | 1.5-2.0x | Medium Process | Medium Voltage Motor |
| PEI Grade 4 | 2.5-3.0x | Thick Paint Film | 110 kV |
| Pai | 2.0-2.5x | Higher Process | High-End Motors |
| Pai Grade 5 | 3.5-4.5x | Thick Paint Film | 220 kV |
| PI | 3.5-4.5x | Complex Process | UHV Transformer |
| PI Grade 5 + | 5.0-8.0x | Extra Thick + Multiple Coatings | 1,000 kV UHV |
| PI + Pai Composite | 5.0-8.0x | Composite Process | UHV High End |
XXVI. Appendix L: 6 Major Enamel Application Case Comparison
| Application | Recommended Film | Film Thickness | BDV | Lifetime |
|---|---|---|---|---|
| 35 kV Power Distribution | PEI Grade 3 | 18-25 μm | > 12 kV | 30 years |
| 110 kV Master | PEI Grade 4 | 30-50 μm | > 20 kV | 30-40 years |
| 220 kV Master | PEI + Pai Grade 4-5 | 40-60 μm | > 25 kV | 40 years |
| 500 kV UHV | PI Grade 5 | 50-80 μm | > 35 kV | 40-60 years |
| 1,000 kV UHV | PI Grade 5 + Multilayer | 70-100 μm | > 50 kV | 60 years + |
| Nuclear 1E | PI Grade 5 Radiation Resistance | 50-80 μm | > 35 kV | 60 years |
XXVII. Appendix M: 5 Major Enameled Wire Supplier Core Capabilities
M.1 International suppliers
- Essex Furukawa (US/Japan): UHV PI enameled wire expert
- Sumitomo Electric (Japan): PI Paint Film Patent
- DuPont (USA): Kapton PI film
- Rea Magnet Wire (USA): UHV enameled wire
M.2 Chinese suppliers
- LP Winding Wire (China): UHV PI enameled wire
- Ningbo Jintian Copper (China): medium pressure enameled wire
- Shanghai Electric Cable (China): High-pressure enameled wire
M.3 Evaluation elements
- UHV Engineering Performance
- PI coating technology
- Dielectric properties
- Life Guarantee
- Localization services
XXVIII. Appendix N: 8 Major Enamel vs Enameled Wire vs Equipment
| Equipment | Film | Thickness | BDV | Life |
|---|---|---|---|---|
| 35 kV Power Distribution Transformer | PEI Grade 3 | 18-25 μm | > 12 kV | 30 years |
| 110 kV main transformer | PEI Grade 4 | 30-50 μm | > 20 kV | 30-40 years |
| 220 kV main transformer | PEI + Pai Grade 4-5 | 40-60 μm | > 25 kV | 40 years |
| 330 kV Transformer | Pai Grade 5 | 50-70 μm | > 30 kV | 40 years |
| 500 kV UHV change | PI Grade 5 | 50-80 μm | > 35 kV | 40-60 years |
| 800 kV HVDC | PI Grade 5 | 60-80 μm | > 40 kV | 50-60 years |
| 1,000 kV UHV change | PI Grade 5 + multilayer | 70-100 μm | > 50 kV | 60 years + |
| 1,200 kV test | PI Grade 5 + multilayer | 80-100 μm | > 50 kV | 40 years |
XXIX. Appendix O: 5 Major Enameled Wire Test Methods
O.1 BDV test
- Standard: IEC 60851/GB 4074
- Voltage boost: 500 V/s
- Acceptance Criteria: > Design Value
- Critical: boost speed, specimen length, electrode shape
O.2 Media Loss Test
- Standard: IEC 60851/GB 4074
- Frequency: 1 kHz/50 Hz
- Qualified: tan δ < 0.005
- Critical: test voltage, temperature
O.3 Paint film continuity test
- Standard: IEC 60851/GB 4074
- Saltwater bath + 7 kV
- Qualified: 0 defects/30 m
- Critical: saline concentration, voltage, time
O.4 Softening breakdown test
- Standard: IEC 60851/GB 4074
- Heating rate: 3°C/min
- Qualified: > Design Temperature
- Key: heating rate, specimen
O.5 Aging test
- Standard: IEC 60172/GB 4074
- Temperature: 180-220°C
- Time: 1,000-5,000 h
- Qualified: Performance retention > 80%
- Critical: temperature, time
XXX. Appendix P: 6 Major Usage Recommendations for Ultra-Thick Enameled Wire
- Voltage matching : Select the film grade according to the operating voltage
- Temperature matching : Select the paint film material according to the operating temperature
- Lifetime matching : select the quality of the paint film according to the service life
- Cost balancing : high performance + reasonable cost
- Supplier certification : UHV engineering performance, UL/TÜV/CSA certification
- Test validation : 6 major tests + accelerated aging