Heat Shrink Stress Control Tube for MV Cable Joints and Terminations (GST)

About Heat Shrink Stress Control Tube for MV Cable Joints and Terminations (GST)

Where the semi-conductive screen of a medium-voltage cable is cut back at a termination or joint, the electric field crowds at the screen edge. Left uncontrolled, that concentrated stress causes partial discharge and eventually breakdown. A stress control tube is the standard heat-shrink answer.

Gala's INSULTUBE Stress Control (code GST) is made from a specially formulated, radiation cross-linked polymeric material with a high dielectric constant (15 minimum on Gala's sheet). Shrunk over the screen end and onto the cable insulation, it spreads the field along its length instead of letting it concentrate at the screen edge. It goes on under the outer insulating or non-tracking tube, and is used in terminations and joints for polymeric cables up to 33 kV (36 kV equipment).

Four sizes cover a range of core diameters: GST 30/12, 40/18, 50/20 and 60/25, where the first figure is the minimum supplied inside diameter and the second the maximum recovered inside diameter, in mm. Recovered walls are 2.3 to 2.4 mm. The tube starts to shrink at 100 deg C and is fully recovered at 130 deg C; shrink it with a soft propane flame as part of the termination or joint build-up. Standard colour is black.

Stress control tube is one component of a termination or joint, not a complete kit; Gala's complete kits are listed separately.

Manufactured by Gala in India. Datasheet and size selection on request.

Specifications

• Brand: Gala
• Product type: Heat shrink stress control tube (field grading), single layer
• Material: Radiation cross-linked polymeric compound, stress-control grade
• Colour: Black
• Voltage rating: For cable joints and terminations up to 33 kV (36 kV equipment)
• Size range: 30 to 60 mm supplied ID; 12 to 25 mm recovered ID
• Wall type / thickness: 2.3 mm to 2.4 mm after recovery (+/-10%)
• Standards tested to: Test methods quoted on Gala's datasheet - ASTM D638, ASTM D2671, ASTM D2240, ASTM D570, ASTM D257, ASTM D150, ESI 09-11, IEC 216
• Application: Electrical stress control at the screen cut of MV polymeric cables in heat-shrink terminations and joints
• Installation: Propane torch, as part of the termination or joint build-up
• Country of origin: India
• Dielectric constant: 15 min (ASTM D150)
• Shrink temperature: Starts at 100 deg C, fully recovered at 130 deg C
• Tensile strength: 12 N/mm2 min (ASTM D638)
• Elongation at break: 350% min (ASTM D638)

Sizes

• GST 30/12 | D 30 | d 12 | T 2.3
• GST 40/18 | D 40 | d 18 | T 2.4
• GST 50/20 | D 50 | d 20 | T 2.4
• GST 60/25 | D 60 | d 25 | T 2.4

Applications: Cable jointing and termination contractors, heat-shrink kit assemblers, power distribution utilities, substations, industrial MV networks, cable repair teams