W2119-2 VPI Insulating Varnish for High-Voltage Motors
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Short Product Description：
W2119-2 is a single-component, solvent-free insulating varnish based on epoxy-modified heat-resistant unsaturated polyester resin. Designed for vacuum pressure impregnation (VPI) of high-voltage motor windings, it is compatible with low-resin-content and medium-resin-content mica tapes. It combines electrical insulation, mechanical strength, and low dielectric loss with heat-activated curing.
- Description
- Technical Data
- FAQ
Description
Product Overview：
W2119-2 is an electrical insulating varnish formulated with epoxy-modified unsaturated polyester resin, a specialty curing agent, and reactive diluent. It is developed for whole-assembly VPI treatment of medium and large high-voltage motors, including explosion-protected motor designs.
Compatibility with low-resin-content and medium-resin-content mica tapes makes W2119-2 suitable for evaluation in mica-based winding insulation systems. After curing, the resin provides mechanical reinforcement and electrical insulation within the impregnated assembly.
The varnish also helps accommodate the effects of differential thermal expansion between metal and insulating materials, reducing stress on the winding structure during temperature changes. Its electrical properties include dielectric strength of ≥25 MV/m under normal conditions and a dielectric dissipation factor of ≤3% at 180°C.
The TDS introduction describes W2119-2 as a Class F resin, while the product features list F and H thermal classes and applications. Confirm the applicable thermal classification for the selected insulation system before specifying an equipment operating-temperature rating.
Key Features and Benefits：
· Designed for High-Voltage Motor VPI: Intended for vacuum pressure impregnation of complete winding assemblies in medium and large high-voltage motors.
· Mica Tape Compatibility: Suitable for use with low-resin-content and medium-resin-content mica tapes, subject to validation with the selected tape system.
· Single-Component Formulation: Simplifies preparation without a separate two-component resin and hardener mixing step.
· Epoxy-Modified Polyester System: Combines electrical insulation with mechanical strength after curing.
· Electrical Performance After Water Exposure: Specified dielectric strength is ≥25 MV/m under normal conditions and ≥22 MV/m after 24 hours of water immersion.
· Low Dielectric Loss: The TDS specifies a dielectric dissipation factor of ≤1% under normal conditions and ≤3% at 180°C.
· High-Temperature Resistivity: Volume resistivity is specified at ≥1 × 10⁹ Ω·m at 180°C, providing a reference for elevated-temperature electrical performance.
· Thermal Stress Accommodation: Helps limit winding stress associated with differences in expansion between metal and insulation materials.
· Heat-Activated Curing: A gel time of 4–7 minutes at 135 ± 2°C characterizes gel formation under laboratory conditions. Complete winding assemblies require the validated baking cycle.
Typical Applications：
W2119-2 insulating varnish is intended for:
· Medium and Large High-Voltage Motors: VPI insulation treatment of motor winding assemblies.
· High-Voltage Explosion-Protected Motors: Whole-assembly impregnation within appropriately qualified motor designs.
· Mica-Based Winding Insulation Systems: Assemblies using low-resin-content or medium-resin-content mica tapes.
· Other Motor and Electrical Windings: Impregnation applications requiring electrical insulation, mechanical reinforcement, and low dielectric loss.
Application in an explosion-protected motor does not make the varnish itself explosion-proof. Finished equipment must meet its applicable design and qualification requirements.
Physical Properties：
| Test Item | Specification |
| Appearance | Pale yellow transparent liquid, free of mechanical impurities |
| Viscosity: Ford Cup No.4 viscometer, 23±2℃ (s) | 20±5.0 |
| Acid value: (mgKOH/g) ≤ | 8 |
| Density: (g/cm³) | 1.04±0.05 |
| Gel time: Test tube method, 135±2℃ (min) | 4-7 |
| Dielectric strength: (MV/m) Normal state: After 24h water immersion: | ≥ 25 ≥ 22 |
| Volume resistivity: (Ω·m) Normal state: After water immersion: 180℃: | ≥ 1×10¹² ≥ 1×10¹¹ ≥ 1×10⁸ |
| Dissipation factor: (%) Normal state: 180℃: | ≤ 1 ≤ 3 |
| Storage stability: (Closed cup method) 50±2℃, 96h (viscosity increase multiple) ≤ | 1 |
| (1) The storage life of this product is 6 months (below 10℃). (2) Curing conditions for items 6 and 7 (varnish cake): 165±2℃ for 4h. (3) Reactive diluent: X-68. | |
Technical Notes:
· Specimens for dielectric strength and volume resistivity testing were cured at 165 ± 5°C for 4 hours.
· Viscosity is expressed as cup flow time in seconds.
· Volume resistivity is reported in Ω·m.
Application Guidance：
· Working Viscosity
Select the working viscosity according to component size, winding structure, and impregnation requirements. The TDS provides these reference ranges:
| Application Category | Reference Working Viscosity |
|---|---|
| General applications | 20–40 s |
| Applications with higher performance requirements | 45 ± 15 s |
| Small electrical components | 12–18 s |
Use the specified X-68 reactive diluent according to the supplier’s instructions. Confirm measurement conditions and the adjustment procedure before production use.
· Reference VPI Process
| Process Step | Reference Condition | Reference Time |
|---|---|---|
| Workpiece pre-baking | 120–125°C | 4 h |
| Loading into the impregnation vessel | Workpiece internal temperature: 40°C | Not specified |
| Evacuation | Vacuum setpoint requires clarification from the supplier | 2 h |
| Resin transfer | Resin temperature: 18–20°C; should not exceed 30°C | Not specified |
| Pressure impregnation | 0.5–0.7 MPa | 3–4 h |
| Draining | Temperature not specified | 25–40 min |
| Baking, stage 1 | 140–150°C | 2 h |
| Baking, stage 2 | 160–170°C | 8–12 h |
The TDS’s vacuum notation is unclear. Confirm the intended vacuum range and whether pressure values are absolute or gauge before configuring the equipment.
The TDS recommends dry air or nitrogen as the pressurizing medium and also mentions filtered air. Select the medium according to the supplier’s instructions and the approved equipment process.
· Curing Validation
Use the two-stage baking schedule as a starting point. Adjust the final baking time according to workpiece size and thermal-performance requirements, as directed in the TDS.
Account for component heating, resin retention, insulation construction, and oven loading. Confirm complete curing throughout the winding assembly before electrical testing or service.
The four-hour laboratory specimen cure and the gel-time test are distinct from the production curing schedule for a complete motor.
· Impregnation Bath Maintenance
For continuous operation, the TDS recommends adding more than 10% fresh resin approximately monthly, with the interval adjusted to actual use. Confirm the replenishment basis with the supplier.
Monitor viscosity and resin condition to maintain consistent impregnation performance.
Precautions：
· Determine the dilution ratio, baking temperature, and baking time experimentally based on product shape, size, and specific requirements.
· The product may absorb moisture and turn whitish under high humidity; performance remains unaffected after baking.
· This product is flammable; keep away from fire and heat sources.
Packaging, Storage/Transport & Shelf Life：
· Packaging: metal pails, 18 KG/pail
· Storage & transport: flammable chemical — keep away from fire and heat; handle per regulations; store cool (RT), dark and dry.
· Shelf life: stored sealed, 6 months at 5-25℃.
Frequently Asked Questions About W2119-2 VPI Insulating Varnish
1. What is W2119-2 insulating varnish used for?
W2119-2 is a single-component, heat-curing epoxy-modified unsaturated polyester insulating varnish developed for whole-assembly vacuum pressure impregnation (VPI) of medium and large high-voltage motors.
It provides electrical insulation and mechanical reinforcement within impregnated windings. Intended applications include mica-based insulation systems and appropriately qualified explosion-protected motor designs.
2. Is W2119-2 compatible with mica tape insulation?
W2119-2 is intended for use with low-resin-content and medium-resin-content mica tapes, subject to validation with the selected tape system.
Before production, evaluate resin penetration, tape compatibility, curing behavior, and electrical performance on representative windings. Compatibility with one mica tape does not establish compatibility with every tape construction or binder system.
3. Can W2119-2 be used in explosion-protected motors?
Yes. The manufacturer lists whole-assembly impregnation of high-voltage explosion-protected motors as an intended application.
Using W2119-2 does not make the varnish itself explosion-proof or qualify a finished motor. The complete equipment design and manufacturing process must meet the applicable requirements for its intended service.
4. What is the thermal class of W2119-2?
The supplied information describes W2119-2 as Class F in the introduction and lists F- and H-class applications elsewhere. Confirm the applicable classification and supporting insulation-system data before specifying an equipment temperature rating.
Electrical testing at 180°C does not independently establish a continuous operating temperature of 180°C for the resin or finished motor.
5. Does W2119-2 require a separate hardener?
W2119-2 is supplied as a single-component formulation and does not require a separate two-component resin and hardener mixing step. It forms a bonded insulating structure through heat curing.
When viscosity adjustment is required, use the specified X-68 reactive diluent according to the supplier’s instructions.
6. What viscosity should be used for W2119-2 impregnation?
The supplied varnish has a specified flow time of 20 ± 5 seconds, measured with a Ford No. 4 cup at 23 ± 2°C.
Select the working viscosity according to winding construction, mica tape system, and impregnation requirements. Confirm the measurement conditions and X-68 adjustment procedure with the supplier. Cup flow time in seconds should not be treated as dynamic viscosity in mPa·s.
7. What preparation is recommended before VPI with W2119-2?
The reference process specifies pre-baking the workpiece at 120–125°C for four hours, then loading it into the impregnation vessel when its internal temperature reaches approximately 40°C.
The reference resin transfer temperature is 18–20°C and should not exceed 30°C. These workpiece and resin temperatures describe different parts of the process and should be controlled separately.
8. What vacuum and pressure conditions are recommended for W2119-2?
The reference process gives an evacuation time of two hours, followed by pressure impregnation at 0.5–0.7 MPa for three to four hours.
9. What curing schedule is recommended for W2119-2?
The reference production cycle specifies draining for 25–40 minutes after impregnation, followed by two-stage baking: 140–150°C for two hours, then 160–170°C for eight to twelve hours.
Validate the schedule according to workpiece size, insulation construction, resin retention, and oven loading. Account for the time required for the winding to reach the target temperature and confirm complete internal curing before electrical testing or service.
10. Does the 4–7 minute gel time mean W2119-2 is fully cured?
No. The specified gel time of 4–7 minutes at 135 ± 2°C describes gel formation under laboratory conditions.
The four-hour laboratory specimen cure is also separate from the production cycle for a complete motor.
11. What electrical insulation performance does W2119-2 provide?
W2119-2 has specified dielectric strength of at least 25 MV/m under normal conditions and at least 22 MV/m after 24 hours of water immersion. These values are equivalent to 25 kV/mm and 22 kV/mm.
Specified volume resistivity is at least 1 × 10¹² Ω·m under normal conditions and at least 1 × 10¹¹ Ω·m after water immersion.
12. What dielectric dissipation factor does W2119-2 provide?
The TDS specifies a dielectric dissipation factor of no more than 1% under normal conditions and no more than 3% at 180°C.
13. How does W2119-2 help reinforce high-voltage motor windings?
After curing, W2119-2 forms a bonded insulating structure that provides mechanical support within the impregnated assembly.
The resin also helps accommodate stress associated with differences in thermal expansion between metal and insulation materials. Actual performance depends on winding design, mica tape compatibility, impregnation quality, and curing.
14. How should a W2119-2 impregnation bath be maintained?
Monitor viscosity and resin condition to maintain consistent impregnation performance. For continuous operation, the TDS recommends adding more than 10% fresh resin approximately monthly, with the interval adjusted to actual use.
Confirm the replenishment percentage basis and adjustment procedure with the supplier before implementing a bath-management routine.
15. Is an MSDS available for W2119-2?
Yes. An MSDS is available for W2119-2 insulating varnish. Contact us to request the current document for handling precautions, exposure controls, storage, and transport information.
If X-68 reactive diluent is used, also request the safety information for that material. The supplied handling guidance identifies W2119-2 as flammable.
16. How is W2119-2 packaged, and what are its storage requirements?
W2119-2 is supplied in 18 kg metal pails. The product-specific TDS note states a storage life of six months below 10°C.
Confirm the complete permitted storage-temperature range with the supplier and follow the current MSDS. Keep the product away from fire and heat sources. The accelerated stability test at 50 ± 2°C for 96 hours is not a recommended storage condition.
17. What information should I provide when requesting a W2119-2 quotation?
Include the motor type, rated voltage, winding dimensions, selected mica tape system, required thermal class, VPI equipment capabilities, and available baking conditions.
For pricing and delivery, provide the required quantity, delivery destination, target delivery date, and any requirements for X-68 reactive diluent, trial material, or an MSDS.