Semiconductive Water-Blocking
Water blocking with partial-discharge control for high-voltage cables
Semiconductive Water-Blocking
Semiconductive water-blocking tapes (WBSC2S) combine longitudinal water-blocking capability with controlled electrical conduction. The semiconductive non-woven polyester backing, impregnated with superabsorbent polyacrylate powder and corrosion inhibitor, provides surface resistivity ≤1500 Ω and volume resistivity <10⁶ Ω·cm, enabling the electric field between layers to be smoothed and the risk of partial discharges in high-voltage cables to be reduced.
In HV power cables, the interfaces between layers at different electrical potentials can generate field concentrations that trigger partial discharges, progressively degrading the insulation. The WBSC2S tape, applied between insulation and shield or under armouring, provides a controlled conduction path that homogenises the potential gradient, eliminating field-concentration points while maintaining water-blocking capability.
Thicknesses range from 0.25 to 0.50 mm with swelling rates reaching ≥18 mm in 3 minutes for heavier-grammage references. Short-term thermal stability of 230°C and continuous service of 90°C per IEC 216 ensure compatibility with extrusion and XLPE cross-linking processes.
Unlike non-conductive water-blocking tapes (CDZD), semiconductive versions are specifically designed for medium- and high-voltage cables where electric-field control is as critical as moisture protection. The double-side semiconductive treatment ensures electrical continuity regardless of tape orientation during taping.
The built-in corrosion inhibitor protects adjacent metallic surfaces — shield, armouring or conductor — from degradation by residual moisture or condensation, extending cable service life in underground or submarine installations where humid environments are permanent.
How to choose the right one?
The right reference depends on the balance between blocking capacity, mechanical strength and available space in the cable construction. All references share the same electrical properties (surface resistivity ≤1500 Ω, volume <10⁶ Ω·cm), so selection is driven by mechanical criteria and absorption capacity.
Standard series
| Reference | Thickness | Grammage | Tensile strength | Swell 1 min | Swell 3 min | When to choose |
|---|---|---|---|---|---|---|
| WBSC2S-30 | 0.30 ±0.03 mm | 110 ±10 g/m² | ≥30 N/cm | ≥8 mm | ≥12 mm | MV cables, standard constructions |
| WBSC2S-35 | 0.35 ±0.03 mm | 120 ±10 g/m² | ≥35 N/cm | ≥9 mm | ≥13 mm | Capacity/space balance |
| WBSC2S-40 | 0.40 ±0.03 mm | 130 ±10 g/m² | ≥40 N/cm | ≥10 mm | ≥14 mm | HV cables, greater protection |
| WBSC2S-50 | 0.50 ±0.03 mm | 160 ±10 g/m² | ≥50 N/cm | ≥12 mm | ≥16 mm | Maximum capacity, EHV cables |
N series (higher swelling capacity)
| Reference | Thickness | Grammage | Tensile strength | Swell 1 min | Swell 3 min | When to choose |
|---|---|---|---|---|---|---|
| WBSC2S-25 | 0.25 ±0.03 mm | 110 ±10 g/m² | ≥25 N/cm | ≥7 mm | ≥10 mm | Tight spaces, rapid response |
| WBSC2S-35N | 0.35 ±0.03 mm | 120 ±10 g/m² | ≥35 N/cm | ≥12 mm | ≥15 mm | High swelling speed |
| WBSC2S-40N | 0.40 ±0.03 mm | 140 ±10 g/m² | ≥40 N/cm | ≥12 mm | ≥16 mm | Maximum response, critical cables |
| WBSC2S-50N | 0.50 ±0.03 mm | 170 ±10 g/m² | ≥50 N/cm | ≥13 mm | ≥18 mm | Maximum protection and speed |
Technical specifications
The values shown below come from tests run to international standards and characterise the material's behaviour both during processing and in service.
Standard series (WBSC2S-30 to WBSC2S-50)
| Property | Test method | WBSC2S-30 | WBSC2S-35 | WBSC2S-40 | WBSC2S-50 |
|---|---|---|---|---|---|
| Thickness (mm) | ISO 9073-2 | 0.30 ±0.03 | 0.35 ±0.03 | 0.40 ±0.03 | 0.50 ±0.03 |
| Grammage (g/m²) | ISO 9073-2 | 110 ±10 | 120 ±10 | 130 ±10 | 160 ±10 |
| Tensile strength (N/cm, min.) | ISO 9073-3 | ≥30 | ≥35 | ≥40 | ≥50 |
| Elongation (%, min.) | ISO 9073-3 | ≥12 | ≥12 | ≥12 | ≥12 |
| Swell rate 1 min (mm) | GB 450 | ≥8 | ≥9 | ≥10 | ≥12 |
| Swell rate 3 min (mm) | GB 450 | ≥12 | ≥13 | ≥14 | ≥16 |
| Moisture content (%) | ISO 287 | ≤9 | ≤9 | ≤9 | ≤9 |
N series (WBSC2S-25 to WBSC2S-50N)
| Property | Test method | WBSC2S-25 | WBSC2S-35N | WBSC2S-40N | WBSC2S-50N |
|---|---|---|---|---|---|
| Thickness (mm) | ISO 9073-2 | 0.25 ±0.03 | 0.35 ±0.03 | 0.40 ±0.03 | 0.50 ±0.03 |
| Grammage (g/m²) | ISO 9073-2 | 110 ±10 | 120 ±10 | 140 ±10 | 170 ±10 |
| Tensile strength (N/cm, min.) | ISO 9073-3 | ≥25 | ≥35 | ≥40 | ≥50 |
| Elongation (%, min.) | ISO 9073-3 | ≥12 | ≥12 | ≥12 | ≥12 |
| Swell rate 1 min (mm) | GB 450 | ≥7 | ≥12 | ≥12 | ≥13 |
| Swell rate 3 min (mm) | GB 450 | ≥10 | ≥15 | ≥16 | ≥18 |
Electrical properties
| Property | Test method | Value |
|---|---|---|
| Surface resistance | GB 3048 | ≤1500 Ω |
| Volume resistivity | GB 3048 | <10⁶ Ω·cm |
Thermal properties
| Property | Test method | Value |
|---|---|---|
| Short-term thermal stability | Q/TR.J02.01-2000 | 230°C |
| Long-term thermal stability | IEC 216-1990 | 90°C |
Construction
| Component | Material |
|---|---|
| Backing | Semiconductive non-woven polyester |
| Active agent | Superabsorbent polyacrylate powder |
| Additive | Corrosion inhibitor |
| Type | Double-sided semiconductive |
Values shown are typical and do not constitute binding specifications.
Available variants
Series
- Standard series — balance between mechanical properties and swelling capacity
- N series — higher swelling speed for critical applications
Non-conductive alternative
- CDZD water-blocking tapes — when partial-discharge control is not required
Delivery formats
The supply format directly influences process continuity and taping efficiency. Material can be supplied in different formats and dimensions adapted to each machine type and production speed.
Pad / Roll (pancake)
Pancake format
Spool (TWS / STS reel)
Automatic reel
Other formats and dimensions available on request. Custom slitting service available.
Application sectors
Need technical advice?
Our technical team is available to help you select the optimum material for your application.
Custom slitting
Up to 1200 mm width, ±0.50 mm tolerance
View service
Spooling
Pad to TWS/STS spool conversion
View serviceWe process material from our stock or material supplied by the customer.
Need technical advice?
Our technical team is available to help you select the optimal material for your application.
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