Glass Fibre Covered Copper & Aluminium Strip Manufacturer in India

✓ ISO 9001:2015 Certified

Glass Fibre Covered Aluminium / Copper Strip

BMI Cables manufactures glass fibre covered copper and aluminium strips rectangular winding conductors wrapped with woven glass fibre and bonded with varnish impregnation. Built for motor stators, generators, transformers, and traction motors where windings face high temperature, mechanical stress, and abrasion that enamel alone cannot survive.

What Is Glass Fibre Covered Strip — And Why Is It Used in High-Temperature Windings?

Glass fibre covered winding wire is made by wrapping woven glass fibre around a rectangular copper or aluminium conductor and bonding it with varnish impregnation. The glass fibre serving forms a tough, abrasion-resistant insulation layer over the conductor — delivering the thermal stability and mechanical strength that demanding winding applications require.

Also known as fiberglass covered strip, glass wrapped rectangular conductor, SGC (single glass covered) or DGC (double glass covered) strip, this winding conductor is the standard choice where enamelled wire reaches its limits. Furnace transformers, traction motors, induction heating coils, and industrial electromagnets all run at temperatures and vibration levels where a varnish-bonded glass fibre covering outperforms enamel-only insulation.

The covering is available as a single glass fibre serving with varnish impregnation (Class F, 155°C) or a double glass fibre serving with varnish impregnation (Class H, 180°C and Class C, 200°C & above) — manufactured to IS 13730 / IEC 60317 glass fibre covered grades. The double serving construction adds dielectric strength, moisture resistance, and mechanical protection for the most critical winding duties.

BMI Cables manufactures glass fibre covered strips on both copper and aluminium conductors at our ISO 9001:2015 certified facility in Bhiwadi, Rajasthan — in sizes from 10 sqmm to 60 sqmm, supplied in coils or spools, with dimensions matched to your winding design at the order stage.

Glass Fibre Covering — Superior Abrasion Resistance

Woven glass fibre serving bonded with varnish creates a mechanically tough insulation layer that withstands winding stresses, vibration, and abrasion protection that enamel coatings alone cannot provide in heavy-duty rotating machines.

Thermal Class F, H and C — Up to 200°C & Above

Three covering constructions across three thermal classes: single glass covered Class F (155°C), double glass covered Class H (180°C), and double glass covered Class C (200°C & above) — matched to your winding’s operating temperature.

Copper or Aluminium Conductor Options

Available on both copper and aluminium rectangular conductors from 10 sqmm to 60 sqmm — letting transformer and motor OEMs balance conductivity, weight, and material cost against the winding design requirement.

IS 13730 Glass Fibre Covered Grades

Manufactured to IS 13730 Part-31, Part-32, and Part-33 (glass fibre covered grades) — so your windings meet the standard your customers and auditors expect, confirmed with test reports on every batch.

Our Glass Fibre Covered Strip Range — Three Covering Constructions

BMI manufactures glass fibre covered strips in single and double glass covered constructions across Class F, Class H, and Class C thermal grades — each to its specific IS 13730 glass fibre covered grade.

Brief Description	Single Glass Covered Strip	Double Glass Covered Strip	Double Glass Covered Strip
Thermal Class	155 (F)	180 (H)	200 (C) & above
Specification	IS 13730 Part-32 (Glass Fibre Covered Grade)	IS 13730 Part-31 (Glass Fibre Covered Grade)	IS 13730 Part-33 (Glass Fibre Covered Grade)
Insulation Type	Single Fibre Serving + Varnish Impregnation	Double Glass Fibre Serving + Varnish Impregnation	Double Glass Fibre Serving + Varnish Impregnation
Range (Copper / Aluminium)	10 sqmm – 60 sqmm	10 sqmm – 60 sqmm	10 sqmm – 60 sqmm
Dielectric Strength	Good	Very Good	Excellent
Heat Shock (°C)	175	200	220
Flexibility & Adherence	Good	Good	Very Good
Application	Furnace & welding transformers, induction heating coils, electromagnets	Traction motors, high-temperature transformers, industrial electromagnets	Critical high-temperature windings requiring moisture & mechanical protection, furnace transformers
Packing	Coil / Spool or As per Customer Requirement	Coil / Spool or As per Customer Requirement	Coil / Spool or As per Customer Requirement

Key Features

What Makes BMI Glass Fibre Covered Strip the Reliable Choice for Transformer & Motor OEMs

The performance parameters that define glass fibre covered wire quality — built into BMI’s manufacturing process, not claimed after the fact.

Uniform Glass Fibre Serving

Woven glass fibre applied with consistent lay and tension along the full strip length — no thin spots, no gaps in coverage. Uniform covering thickness is what delivers predictable turn-to-turn insulation in the finished winding.

Varnish Impregnation That Bonds, Not Just Coats

The varnish impregnation penetrates and bonds the glass fibre serving to the conductor — locking the covering in place so it survives the bending, forming, and tensioning of coil winding without fraying or displacement.

Three Distinct Thermal Classes — Not Relabelled Variants

Class F, Class H, and Class C constructions each use their specific serving and varnish system per the applicable IS 13730 part. Each thermal class is a distinct product, confirmed by batch test report with every order.

Heat Shock Performance Up to 220°C

Heat shock ratings of 175°C, 200°C, and 220°C across the three grades — so windings hold their insulation integrity through thermal cycling in furnace transformers and traction motor duty.

Moisture & Mechanical Protection for Critical Windings

The double glass covered construction adds the moisture resistance and mechanical armour needed in critical high-temperature windings — where insulation failure means machine failure.

Copper & Aluminium, 10–60 sqmm, Made to Order

Both conductor metals, full size range, coil or spool packing, dimensions confirmed at order stage. Direct from our Bhiwadi plant — share your spec sheet and we confirm feasibility within 24 hours.

FAQ - Glass Fibre Covered Aluminium / Copper Strip

Q1: What is the difference between single glass covered (SGC) and double glass covered (DGC) strip?

Single glass covered strip has one layer of glass fibre serving with varnish impregnation and is rated Class F (155°C). Double glass covered strip has two layers of glass fibre serving, giving higher dielectric strength, better moisture and mechanical protection, and thermal ratings of Class H (180°C) or Class C (200°C & above).

Q2: Is glass fibre covered strip available on both copper and aluminium conductors?

Yes. BMI manufactures glass fibre covered strips on both copper and aluminium rectangular conductors, in sizes from 10 sqmm to 60 sqmm.

Q3: Which standard does BMI glass fibre covered strip conform to?

BMI glass fibre covered strips are manufactured to IS 13730 glass fibre covered grades — Part-32 (Class F), Part-31 (Class H), and Part-33 (Class C).

Q4: When should I choose glass fibre covered strip over enamelled strip?

Choose glass fibre covered strip when the winding faces high operating temperature, thermal cycling, vibration, or abrasion — such as furnace transformers, traction motors, and induction heating coils. The varnish-bonded glass fibre covering provides mechanical and thermal protection beyond what enamel-only insulation offers.

Q5: What packing options are available?

Glass fibre covered strips are supplied in coils or on spools, or as per your requirement.