High Shrink Films & Tapes for Electrical Coils

Sacrifice Films for HV Coils

Industry

High Voltage Motors and Generators

Application

Large OEM in the power generation industry looks to cost reduce their current release film.

Problem

Current film is expensive to use as a sacrifice layer and provides very little compaction when heated during the press cycle. Low compression force can lead to poor insulation consolidation and improper shaping of the corner radii on the HV coils. 

Dunstone Solution

This high shrink solution for electrical coils offers high compaction force, which is ideal for this application. This product provides consistent release at temperatures above 170 °C, which is important when working with electrical coils.

Our high shrink solutions for electrical coils are an inexpensive yet effective option for a compression layer in electrical coils. Since the hi-shrink tape increases pressure as it heats up, it provides solid compression and proper shaping.

Dunstone 140-Series Hi-Shrink Tape with Release

Dunstone 200-Series Hi-Shrink Tape with Release

Implementation

The OEM was able to use Dunstone’s heat shrink tape as the first layer of release film instead of the film currently used. Our shrink tape provides the high temperature release characteristics of Teflon®, combined with the high shrink force of our modified polyester film at an overall lower cost. 

Other applications for Dunstone tapes on high voltage coils

• Heat shrinkable release film on resin rich insulation for DC Field Poles
• Heat shrinkable release film on pre-consolidated coils

Case Study End Winding Insulation for HV Coils

Industry

High Voltage Motors and Generators

Application

OEM in the power generation industry want to guard against fatigue and wear of end-windings on HV coils.

Problem

Machine end-windings are subject to higher rates of fatigue and wear of insulation materials due to their location outside of the stator core, and not being protected by the steel of the stator slot.  Aging of the support and tie structure for the windings, as well as resonance conditions can lead to conductor and insulation fatigue cracks, causing high arcing currents.

Dunstone Solution

Dunstone 220R and 515R Hi-Shrink Tapes

Implementation

The OEM uses Dunstone Hi-Shrink Tape during the insulation stage of the coil end windings to achieve maximum consolidation of the insulation materials on the exposed end-windings as well as curved knuckles of the coils where sharp coil radii make it more challenging to fully consolidate insulation layers.  Depending on the amount of compaction force needed, 220R or 515R can provide exceptionally high levels of external shrink force to the insulation layers during the coil pressing/curing cycle.   The Hi-Shrink Tape also allows for the outer layer of insulation material to have a smooth surface, reducing the need for rework to eliminate possible arcing points.