Pressboard Oil Duct Spacer are critical in maintaining precise cooling channels and ensuring the mechanical integrity of winding insulation. The material you choose affects not just thermal performance, but also long-term dielectric stability and mechanical durability.
Whether you’re building an oil-immersed or dry-type transformer, selecting the right spacer material is essential. This guide compares the top three materials: pressboard, FRP, and epoxy blocks — to help you source with confidence.
Pressboard Oil Duct Spacers (Most Common for Oil-Immersed Transformers)
Material Definition
Pressboard is a cellulose-based insulation board, manufactured in accordance with IEC 60641, widely used in oil-immersed transformers.
Key Benefits
- ✅ Excellent dielectric strength when saturated in oil
- ✅ Compatible with mineral and ester-based transformer fluids
- ✅ Easy to CNC-cut, slot, notch, or chamfer
- ✅ Cost-effective and globally sourced
Common Applications
- Vertical cooling channel spacers between HV/LV coil layers
- Chamfered wedge blocks inside winding stacks
- Structural supports within the transformer core duct
🧰 Available Specs:
Thickness: 2mm–10mm
Certification: IEC 60641, SGS-tested grades available
FRP Cooling Channel Spacers (For Dry-Type Transformers)
Material Definition
FRP (Fiberglass Reinforced Plastic) is a composite made from woven or chopped fiberglass and high-temperature resins. It’s built for mechanical rigidity and thermal endurance.
Key Benefits
- ✅ High structural strength under coil compression
- ✅ Heat resistance above 130°C
- ✅ Flame-retardant grades available for dry-type use
- ✅ Low moisture absorption, improving dimensional stability
Common Applications
- Vertical channel strips in dry-type windings
- Reinforced support ribs inside open-core designs
- Grooved or tab-locking insulation strips
🧰 Machining Capabilities:
Grooved edges, rounded corners, and punch slots available on request
Epoxy Spacer Blocks (Rigid & Thermally Stable)
Material Definition
Epoxy spacers are rigid blocks made from epoxy resin, often reinforced with kraft paper or fiberglass. These are used in high-load or high-temperature zones, especially in compact transformers.
Key Benefits
- ✅ Extremely high compressive strength
- ✅ Vacuum-dry stable and thermally cured
- ✅ Supports precision CNC milling and pre-shaping
- ✅ Suitable for structural support under winding tension
Common Applications
- Radial spacer blocks under coil pressure zones
- Base and frame insulators in dry-type designs
- Reinforced insulation parts in HV transformer builds
🧰 Available as:
Molded blocks, CNC-laminated sheets, or high-density composite slabs
Side-by-Side Comparison Table
| Feature / Property | Pressboard | FRP Composite | Epoxy Spacer Block |
|---|---|---|---|
| IEC Compliance | Yes (60641) | Optional | Optional |
| Use in Oil-Immersed | ✅ Excellent | ❌ Not recommended | ❌ Only in dry zones |
| Mechanical Strength | Moderate | High | Very High |
| CNC Machining | ✅ Easy | ✅ Moderate | ✅ Excellent |
| Moisture Resistance | Moderate | High | High |
| Common Application | Standard coil spacers | Dry-type ducts | Load-bearing blocks |
Which One to Choose for Your Transformer Build?
| Use Case | Best Material Option |
|---|---|
| Oil-filled winding layer spacers | Pressboard (IEC 60641) |
| Dry-type high-clearance vertical channels | FRP Composite |
| Mechanical load zones or high-heat areas | Epoxy Spacer Block |
| Custom coil shape matching | CNC-processed pressboard |
✅ Tip: Confirm material compatibility with your transformer’s operating temperature, voltage class, and drying method. Improper material selection can lead to insulation degradation or cooling inefficiency.
Request Technical Specs or Full Material Kit
We offer OEM-standard and custom spacer components made from:
- Pressboard duct strips cut to winding height
- Epoxy spacer blocks with CNC slotting
- FRP vertical wedges for dry-type coil support
📩 Send us your drawing or part list — we’ll match with the ideal material and size.
📞 Contact Us
Phone: +86-15958243831
Email: jessie.feng@sidanm.com
Whatsapp: https://wa.me/8615958243831
