Motor & Transformer Insulation Tapes for Coils, Leads and Dry-Type Transformers
A request for “electrical insulation tape” is rarely specific enough for a reliable quotation.
A motor manufacturer may need to anchor a lead wire, hold an end turn or reinforce a coil during varnish curing. A dry-type transformer manufacturer may need a tape for coil banding, crossover insulation or lead stabilization. A small bobbin-wound transformer may need a thinner construction that does not add too much build to the coil.
These applications may look similar, but the tape requirements are different.
The main products in this range are:
- PET film reinforced with continuous glass filaments;
- PET film laminated with fiberglass cloth;
- woven glass cloth tape;
- polyimide film tape with acrylic or silicone adhesive.
The products are mainly positioned for motors, generators, dry-type transformers, resin-processed coils and selected electrical assemblies.
Dry-Type and Oil-Filled Transformer Applications
The first selection question is not whether the transformer is large or small. It is whether the tape will be used in a dry-type or oil-filled system.
Dry-Type Transformers
The following products can be considered for dry-type transformer assembly, depending on the insulation position and process:
- Standard Filament-Reinforced Electrical Tape (F-380) for lead anchoring, coil banding and general reinforcement;
- High-Strength Filament-Reinforced Electrical Tape (F-380A) for higher mechanical loads;
- PET Fiberglass Cloth Tape (F-390) for coil insulation, banding and crossover support;
- selected Glass Cloth Tape (G-430) grades for outer wrapping, lead protection and abrasion resistance;
- selected Acrylic Polyimide Tape (K-610) applications where thin insulation or fine-wire fixing is required.
These products should be tested with the actual varnish, resin, curing temperature, dwell time and winding geometry.
Oil-Filled Transformers
The standard products listed on this page should not be treated as pre-qualified for direct oil-filled transformer service.
F-380, F-380A and F-390 are mainly positioned for dry-type transformer applications. G-430, K-610 and K-620 also require separate oil-compatibility verification before use in transformer oil.
For an oil-filled transformer, the supplier must confirm the exact grade and provide supporting data for:
- insulating oil compatibility;
- thermal aging;
- dielectric retention;
- adhesive stability;
- dimensional change;
- conductor or copper corrosion;
- long-term immersion behavior.
If your project involves an oil-filled transformer, state this clearly when requesting a quotation. Do not select a tape only from its tensile strength, dielectric breakdown or temperature figure.
Motor and Generator Winding Applications
Motor and generator manufacturers usually need tape for lead anchoring, coil banding, end-turn wrapping, ground-insulation holding or mechanical reinforcement.
A PET film/glass filament construction is often considered when the tape must resist stretching and carry tension along the tape direction. A woven glass cloth tape may be more suitable where abrasion, edge contact or outer coil protection is also important.
For motor and generator applications, the first products to compare are:
- Standard Filament-Reinforced Electrical Tape (F-380);
- High-Strength Filament-Reinforced Electrical Tape (F-380A);
- PET Fiberglass Cloth Tape (F-390);
- Glass Cloth Tape (G-430).
The choice should be based on the actual failure risk. A tape that breaks during winding requires a different solution from a tape that shifts during curing or wears against a sharp coil edge.
Small Transformers, Bobbin-Wound Coils and Inductors
Small transformers and compact coils often have limited space, fine wire and tighter dimensional requirements. A thick reinforcement tape may provide strength but create too much coil build or interfere with clearance.
For these assemblies:
- Acrylic Polyimide Tape (K-610) may be considered for selected fine-wire fixing and thin insulation;
- PET Fiberglass Cloth Tape (F-390) may be considered where composite reinforcement is needed;
- Standard Filament-Reinforced Electrical Tape (F-380) may be considered where mechanical holding is more important than minimum thickness;
- Glass Cloth Tape (G-430) may be suitable for selected outer wrapping or abrasion protection.
Polyimide tape is not automatically better than PET or glass cloth tape. It becomes relevant when thin construction, dimensional stability or a specific adhesive requirement is more important than heavy mechanical reinforcement.
Select the Tape by Its Position in the Assembly
Lead Wire Anchoring
Lead anchoring is a mechanical holding application with an insulation requirement. The tape must keep the conductor in position without excessive stretching and must remain compatible with the surrounding insulation materials.
Standard Filament-Reinforced Electrical Tape (F-380) is a practical starting point for standard lead anchoring. High-Strength Filament-Reinforced Electrical Tape (F-380A) may be considered when the lead or anchoring point is subject to higher pull or movement.
Tape width, overlap and anchoring length matter as much as adhesive tack. A stronger grade will not correct an insufficient wrap or a poorly prepared surface.
Coil Banding and End-Turn Wrapping
Coil banding and end-turn wrapping can expose the tape to pulling force, handling stress, abrasion and thermal cycling.
- F-380 provides PET film insulation with continuous glass-filament reinforcement.
- F-380A provides a higher-strength construction for heavier mechanical requirements.
- F-390 combines polyester film with fiberglass cloth.
- G-430 provides a woven glass cloth backing and several adhesive options.
The best starting point depends on whether the main concern is low stretch, edge protection, puncture resistance, wrapping behavior or process compatibility.
Crossover and Ground-Insulation Holding
Crossover insulation and ground-insulation holding require stable positioning and controlled thickness. The tape may support the insulation during winding or assembly, but it should not automatically be treated as a replacement for the complete slot liner, phase separator or primary insulation system.
PET Fiberglass Cloth Tape (F-390) is a suitable product family to evaluate for crossover insulation, coil banding and ground-insulation support. Acrylic Polyimide Tape (K-610) may be considered for selected thin insulation or compact coil applications.
Fine-Wire Fixing
Fine-wire applications usually place greater emphasis on thinness, dimensional stability and controlled adhesive performance.
Acrylic Polyimide Tape (K-610) is positioned for selected Class F / 155°C electrical insulation and fine-wire fixing applications. It can be considered for compact coils, small transformers and selected motor or dry-type transformer processes.
It is not the preferred starting point when the main requirement is heavy coil banding or high-load lead anchoring.
Product Selection by Construction
PET Film with Continuous Glass Filaments
Standard Filament-Reinforced Electrical Tape (F-380) combines PET film, continuous glass filaments and acrylic adhesive.
It is mainly used for:
- motor winding;
- generator coils;
- dry-type transformer assembly;
- lead wire anchoring;
- coil banding;
- end-turn taping;
- ground-insulation holding.
The published product positioning is Class F / 155°C. Direct oil-filled transformer service requires separate qualification.
High-Strength Filament-Reinforced Electrical Tape (F-380A) uses the same general construction in a thicker 0.17 mm grade. It is intended for heavier winding assemblies, higher-load lead anchoring and stronger coil reinforcement.
PET Film Laminated with Fiberglass Cloth
PET Fiberglass Cloth Tape (F-390) combines polyester film, fiberglass cloth and acrylic adhesive.
It is mainly used for:
- motor winding;
- dry-type transformer coil insulation;
- lead stabilization;
- coil banding;
- crossover insulation;
- generator coil wrapping.
This construction is different from PET film with continuous glass filaments. Buyers comparing the two should consider the required balance of tensile strength, tear resistance, thickness, wrapping behavior and surface contact.
The difference is covered in PET Fiberglass Cloth Tape vs Filament-Reinforced Electrical Tape within our Comparison Articles.
Woven Glass Cloth
Glass Cloth Tape (G-430) uses woven fiberglass cloth and is available with rubber, acrylic or silicone adhesive systems.
Typical applications include:
- lead and coil wrapping;
- outer coil wrapping;
- end-turn taping;
- lead protection;
- abrasion protection;
- mechanical reinforcement.
The adhesive system must be matched to the actual temperature, varnish or resin, surface condition and required holding power. G-430 should not be treated as oil-compatible without specific test data.
Polyimide Film
Acrylic Polyimide Tape (K-610) uses polyimide film with acrylic adhesive. It is positioned for selected Class F / 155°C applications, fine-wire fixing and thin electrical insulation.
Silicone Polyimide Tape (K-620) uses silicone adhesive and is mainly positioned for wave solder masking, powder-coating masking and selected high-temperature electrical processes.
K-620 should not be treated as the default transformer insulation tape. It is also unsuitable where the process has a strict no-silicone requirement.
What to Confirm Before Ordering
A product name is not enough for an electrical insulation RFQ. Ask for the latest Datasheets and confirm:
- backing material and construction;
- adhesive chemistry;
- total thickness;
- tensile strength and test direction;
- elongation;
- adhesion to the actual substrate;
- dielectric breakdown;
- thermal class or temperature basis;
- varnish and resin compatibility;
- transformer-oil compatibility;
- copper corrosion data;
- roll width, length and core size;
- test method;
- whether values are typical, minimum or specification data.
For a dry-type transformer, include the varnish or resin type and curing profile in the inquiry. For an oil-filled transformer, include the oil type, expected temperature and immersion conditions.
Qualification Before Bulk Approval
Before requesting samples, provide:
- equipment type;
- winding construction;
- tape position;
- conductor or insulation surface;
- tape width;
- wrapping method;
- mechanical load;
- curing temperature and dwell time;
- varnish, resin or oil exposure;
- current failure mode.
Test the tape on the actual conductor, insulation paper, PET film, copper strip or coil surface.
For dry-type and resin-processed applications, inspect the tape before and after curing. For oil-filled applications, use the actual transformer oil and temperature conditions during qualification.
If the tape fails, identify the failure instead of simply changing to a thicker product:
- backing breakage;
- stretching and loosening;
- loss of adhesion;
- lead movement;
- softening during curing;
- change after oil exposure;
- damage to adjacent insulation.
For process-related problems, the Troubleshooting resources can help organize the failure information before another grade is selected. Product-specific technical documents are available through Datasheets.
Related Products:
Standard Filament-Reinforced Electrical Tape (F-380)
High-Strength Filament-Reinforced Electrical Tape (F-380A)
PET Fiberglass Cloth Tape (F-390)
Acrylic Polyimide Tape (K-610)
Browse All Tape Datasheets
FAQ
Start with Standard Filament-Reinforced Electrical Tape (F-380) for standard holding requirements. Consider High-Strength Filament-Reinforced Electrical Tape (F-380A) when the lead or coil applies higher mechanical load. PET Fiberglass Cloth Tape (F-390) is another candidate where a PET/fiberglass cloth composite is preferred.
No. PET Fiberglass Cloth Tape uses polyester film laminated with fiberglass cloth. Filament-Reinforced Electrical Tape uses PET film with continuous glass filaments. They can overlap in coil applications, but their wrapping and mechanical behavior are different.
Choose Glass Cloth Tape (G-430) when woven reinforcement, abrasion protection, outer wrapping or lead protection is important. Choose F-380 or F-380A when longitudinal tensile holding and low stretch are the main requirements.
Polyimide tape may be suitable for selected thin insulation, fine-wire or compact-coil applications. It should not automatically be selected for heavy lead anchoring or large coil banding, where PET/glass filament or glass cloth constructions may provide more appropriate mechanical support.
The published positioning of F-380, F-380A, F-390 and K-610 is primarily Class F / 155°C. Class H use requires a suitable grade, complete insulation-system evaluation and supporting technical documentation.
Send the motor or transformer type, dry-type or oil-filled status, winding structure, tape position, conductor material, required width, curing or operating temperature, resin or oil exposure and current failure problem.
Request Technical Information and Samples
Tell us whether the tape is for a motor, generator, dry-type transformer, small bobbin-wound coil or oil-filled transformer.
Include the insulation position, mechanical load, process temperature and exposure to varnish, resin or oil. We can provide the relevant Datasheets, recommend a suitable starting construction and arrange sample rolls for qualification before bulk ordering.