Mica Tape for VPI

Description

Product Composition & Technology

Our Mica Tape for VPI features a specialized three-layer structure designed for optimal resin penetration and long-term reliability :

1. Mica Paper Base: Manufactured from calcined muscovite or phlogopite mica, providing inherent dielectric strength up to 25kV/mm and thermal resistance exceeding 500°C

. The uncalcined porous structure ensures rapid VPI resin absorption .

2. Reinforcement Layer: Choose from multiple backing materials based on your application:

E-Glass Fabric: For maximum mechanical strength and tear resistance (33-40 g/m²)
Polyester Film (PET): For excellent flexibility and cost-effective insulation (0.025mm thickness)
Polyimide Film (PI): For ultra-thin, high-temperature aerospace applications
Polyester Felt: Enhanced resin retention for hand-application scenarios

3. Low-Resin Binder System: Epoxy or silicone resin content is controlled below 15% (typically 10-12 g/m²)

to ensure compatibility with all major solvent-free VPI resins while maintaining tape integrity during coil winding.

Key Performance Advantages

Superior Impregnability: Air porosity >1600 seconds/100ml enables complete resin saturation, eliminating voids that cause partial discharge
Mechanical Robustness: Tensile strength of 150 N/cm prevents tearing during high-speed automated taping
Thermal Classification: Available in Class F (155°C) and Class H (180°C) ratings
Chemical Compatibility: Zinc naphthenate accelerator ensures rapid curing with epoxy and polyesterimid VPI systems
Voltage Endurance: Proven performance in equipment rated from 10kV to 27kV with insulation thickness of 2-7mm

Technical Data Tables

Standard Glass Fabric Reinforced VPI Mica Tape

Parameter	Value / Range	Test Method
Nominal Thickness	0.10 – 0.18 mm (±0.01)	IEC 60371-2
Total Substance	118 – 164 g/m²	IEC 60371-2
Mica Paper Content	70 – 113 g/m²	IEC 60371-2
Glass Fabric Content	33 g/m²	IEC 60371-2
Resin Binder Content	10 – 12 g/m² (<15%)	IEC 60371-2
Aramid Fibroids	5 – 7 g/m² (when specified)	IEC 60371-2
Tensile Strength	≥150 N/cm	IEC 60371-2
Dielectric Strength	15 – 25 kV/mm	IEC 60243
Air Porosity	>1,600 – 2,500 s/100ml	IEC 60371-2
Volatile Content	≤0.5%	IEC 60371-2
Temperature Class	155°C (Class F) / 180°C (Class H)	UL 1446
Standard Width	5mm – 1,000mm (custom slitting available)	–
Roll Length	500m / 1,000m / 2,000m	–

Typical values based on industry standards and competitor specifications

Product Variants by Backing Material

Product Code	Reinforcement	Thickness (mm)	Mica Content (g/m²)	Key Application
SIDA-VPI-G	Glass Fabric	0.13 – 0.15	120 – 160	High-voltage coils, traction motors
SIDA-VPI-P	Polyester Film	0.10 – 0.13	70 – 90	General purpose motors to 11kV ****
SIDA-VPI-F	Polyester Felt	0.18 – 0.20	140 – 160	Hand-wound coils, end-winding covers
SIDA-VPI-PI	Polyimide Film	0.08 – 0.12	90 – 110	Wind turbines, aerospace compact windings

Note:The product specifications provided are for reference purposes only. Please refer to the actual product for final specifications. We also offer various sizes and thicknesses to meet your specific needs. For further customization, please contact us.

Application Scenarios

1. High-Voltage AC Motor Groundwall Insulation

Scenario: 6.6kV – 13.8kV industrial motors in pulp/paper mills and petrochemical plants

Benefit: Mica tape’s low binder content ensures complete epoxy resin penetration during VPI, creating void-free insulation that prevents partial discharge and extends motor life beyond 30 years.

2. Wind Power Generator Stator Coils

Scenario: Direct-drive wind turbines (1.5MW – 8MW) subject to thermal cycling and vibration

Benefit: Glass fabric reinforcement withstands mechanical stress while maintaining flexibility for large coil sizes up to 7mm insulation thickness. Temperature class H (180°C) rating handles overload conditions.

3. Traction Motors for Railway Systems

Scenario: High-speed train motors requiring temperature class C (200°C+) performance

Benefit: Aramid fiber-infused mica tape (366.85 type) provides exceptional mechanical strength and thermal stability for frequent start-stop operations and voltage spikes.

4. Hermetic & Submersible Motors

Scenario: Refrigeration compressors and irrigation pumps exposed to moisture and refrigerants

Benefit*: PET mat backing improves handling and creates a moisture barrier post-VPI, ensuring reliable operation in sealed environments.

5. DC Motor Field Coil Enhancement

Scenario: Upgrading existing DC motors for improved heat transfer and voltage endurance

Benefit*: Mica tape increases thermal conductivity by 15-20% compared to traditional insulation, reducing hotspot temperatures.

6. Transformer Barrier Insulation

Scenario*: Oil-filled power transformers requiring inter-layer insulation

Benefit*: Compatible with both epoxy VPI and transformer oil, providing dual protection against electrical tracking.

Frequently Asked Questions (FAQs)

Q1: What makes VPI mica tape different from resin-rich mica tape? A: VPI mica tape contains less than 15% resin binder (vs. >35% in resin-rich) ****, allowing it to absorb and integrate with impregnation resin during vacuum-pressure processing. This creates a homogeneous insulation structure with superior dielectric and thermal properties compared to pre-cured tapes.

Q2: How do I select the right backing material?

Glass Fabric: Choose for highest mechanical strength and temperatures above 155°C
Polyester Film: Optimal for cost-sensitive applications up to 11kV with good flexibility ****
Polyimide Film: Select for space-constrained or aerospace applications requiring 180°C+ performance
Felt Backing: Best for manual application on complex coil ends

Q3: What VPI resin systems are compatible? A: Our tapes are validated for use with unsaturated polyesterimide (3308/3309), bisphenol-A epoxy (3407). Zinc naphthenate accelerator ensures rapid gelation.

Q4: What is the recommended taping tension and overlap? A: Apply 20-30 N tension with 50% overlap for automated taping, or 33% overlap for manual application. Maintain 3-5% tape stretch to avoid buckling..

Q5: How should the tape be stored? A: Store in original packaging at 15-25°C and <65% relative humidity. Shelf life exceeds 12 months due to low volatile content (<0.5%).

Q6: Can this tape be used for fire-resistant cables? A: While primarily designed for rotating machines, phlogopite-based variants provide UL 94 V-0 flame retardancy for critical cable applications.

Quality Assurance & Testing Standards

International Compliance

IEC 60371-2: Specifications for mica paper tapes (thickness, substance, tensile strength)
IEC 60371-3-4: Specific requirements for VPI-compatible tapes (porosity, binder content)
UL 1446: Insulation systems certification for Class F (155°C) and Class H (180°C)
GB/T 5019: Chinese national standard for electrical insulating materials
JIS C 2116: Japanese standard for mica tape testing methods

In-House Testing Protocol

Every SIDA Mica Tape batch undergoes:

Dielectric Breakdown Voltage: AC ramp test per IEC 60243
Resin Flow Characteristics: VPI simulation at 80°C/100mbar
Thermal Aging: 1000 hours at rated temperature class
Porosity Measurement: Gurley method (S/100ml)
Mechanical Strength: Tensile and edge tear resistance

Certifications

ISO 9001:2015 Quality Management System
IATF 16949 (for automotive traction motor grades)
REACH/RoHS compliance for environmental safety