35kV Busbar Heat Shrink Casing (MPG35 Series)

Heavy-wall anti-tracking heat shrink casing for 26/35kV switchgear and substation busbars, where flashover risk and outdoor exposure are highest.

MPG35 is the heavier-wall member of the busbar casing family, built for 26/35kV duty. At this voltage the creepage distance and the surface tracking resistance are the binding constraints, so the wall is thicker, the anti-tracking additive load is higher, and the recovered profile has to stay uniform across a large busbar with a wide tolerance band. It is the grade specified when the busbar leaves the controlled switchroom and goes into a substation or a mining switchroom.

35kV is where flashover stops being a theoretical risk and becomes a field failure mode. A contaminated or moisture-wetted sleeve surface will track before the dielectric through-thickness is ever challenged. The casing therefore earns its keep on two fronts: it keeps phases close enough to make the cubicle buildable, and it resists the surface breakdown that plain sleeving invites outdoors. We usually sell it alongside 35kV cold-shrink accessories as one insulation package to substation and mining OEMs.

Technical specifications

Applications by industry

• 35kV switchgear OEM busbar insulation
• Substation equipment and bay busbars
• Mining and heavy-industry 35kV switchgear
• Renewable (wind/solar) substation busbars
• Heavy-wall busbar sleeving for exposed duty
• Phase-clearance reduction at 35kV

35kV flashover and why wall thickness matters

Doubling the voltage does not double the problem -- it changes the failure mode. At 35kV the surface is the weak link: a film of contamination with moisture tracks long before the wall breaks down. The heavier wall plus a higher anti-tracking filler raises the inclined-plane performance, and uniform recovery keeps the creepage path intact at corners. Outdoor grades add UV stability so the surface does not chalk and lose tracking resistance in sunlight.

Uniform recovery on a large busbar and end treatment

Large busbars carry wide tolerance, so the supplied ID has to clear the worst-case width and height while still shrinking tight on the best case. Heat the wall evenly with a reflector so it follows the corners instead of lifting off them, and treat the ends as the real weather barrier: an open or poorly sealed end lets water run along the bar under the sleeve and track at the support. Where the bar exits to open air, use a weather boot or sealed end cap.

Inspection and traceability

We map wall thickness along the length, verify recovered ID against the busbar section, and run inclined-plane tracking, flame and hi-pot tests on request for type-tested 35kV packages.

• Supplied and recovered ID versus busbar section
• Wall-thickness mapping (heavier wall verified)
• Inclined-plane tracking test on request
• Flammability (V-0) and hi-pot on request
• UV-stability check for outdoor grades on request

Related components

Common questions