Heat Shrink Stress Control Tubing
Semi-conductive heat shrink tubing for electric field stress control at medium voltage cable terminations. Redistributes the concentrated electric field at the screen cutback point — preventing insulation breakdown at 6.6kV to 36kV.
Why Stress Control is Essential at Cable Terminations
In medium voltage cable terminations, cutting back the cable screen creates an abrupt end to the equipotential shielding layer. At this point, the electric field lines are forced to converge, creating a region of extremely high field intensity at the screen cutback edge. If left unmanaged, this field concentration causes partial discharge, surface tracking and eventual insulation breakdown — a leading cause of MV cable termination failure.
Heat shrink stress control tubing solves this problem by providing a controlled-resistivity path that redistributes the field lines over a longer distance, reducing peak field intensity below the breakdown threshold. VIKCHEM's stress control tubing is a mandatory component of all heat shrink termination kits for cable systems above 6.6kV, and is tested per IS 13573 and IEC 60502 type test protocols.
Technical Specifications
| Property | Value |
|---|---|
| Voltage Range | 6.6kV – 36kV |
| Tubing Type | Resistive semi-conductive |
| Shrink Ratio | 3:1 |
| Volume Resistivity | 10² – 10⁴ Ω·cm |
| Temperature Range | -40°C to +130°C |
| Standards | IS 13573, IEC 60502 |
Installation
The stress control tube is positioned to overlap the cable screen cutback by the specified distance (as per kit instructions — typically 20–30mm), with the remainder extending onto the cable insulation. On heating, the tube shrinks uniformly and achieves intimate contact with the cable surface. The defined resistivity of the semi-conductive compound then redistributes the electric field over the overlap length.
Used In
- ›All MV terminations above 6.6kV
- ›XLPE and PILC cable terminations
- ›Indoor switchgear terminations
- ›Outdoor overhead cable ends
- ›Transformer and RMU connections