PE/PA Polyethylene Insulation&Nylon Sheath Winding Wires for Submersible Motor

Conductor Construction: Solid and Stranded Options

PE/PA winding wires are manufactured with high-conductivity annealed copper conductors in both solid and stranded configurations. The choice between solid and stranded construction depends on the required cross-sectional area, winding flexibility, and motor design specifications.

Solid conductors are available in diameters from 0.6 mm to 4.6 mm, corresponding to cross-sectional areas of 0.283 mm² to 16.6 mm² . The standard production range for submersible motor applications typically falls between 0.8 mm and 3.4 mm . These dimensions cover the majority of small to medium submersible pump motors where the winding process can accommodate a relatively stiff conductor.

Stranded conductors extend the range to larger cross-sections, with diameters from 4.5 mm to 17.1 mm and cross-sectional areas of 3.5 mm² to 150 mm² . Common stranded configurations include 7-strand constructions such as 0.80 mm × 7 and 1.12 mm × 7, as well as 19-strand designs ranging from 0.69 mm × 19 to 1.18 mm × 19 . The multi-strand design provides the flexibility necessary for winding into motor stator slots while maintaining the required current-carrying capacity.

Conductor diameter tolerances are specified according to applicable product standards. For the Indian market, tolerances range from ±0.004 mm for 0.4 mm conductors to ±0.019 mm for 1.9 mm conductors . These tight dimensional controls ensure consistent insulation application and predictable electrical performance.

Insulation System: PE and PA Layer Dimensions

The double insulation system consists of an inner polyethylene (PE) layer and an outer polyamide (PA) sheath, commonly referred to as nylon. Each layer has distinct dimensional requirements that affect the wire‘s electrical and mechanical performance.

The PE insulation wall thickness depends on the conductor dimensions and the operating voltage. Minimum insulation thickness begins at 0.2 mm for conductors up to 1.3 mm, increasing to 0.25 mm for conductors from 1.4 mm to 1.9 mm, and further for larger conductor sizes . For standard 450/750 V applications, the PE layer provides the primary dielectric barrier.

The PA sheath is applied over the PE insulation as a surface protection layer. Typical PA wall thickness ranges from 0.1 mm to 0.2 mm, depending on the outer diameter of the insulated conductor . Representative product data shows PA wall thicknesses of 0.15 mm for smaller conductor sizes and 0.20 mm for larger sizes . The polyamide sheath must be tightly applied with no voids or separation from the underlying PE layer. The PA layer provides mechanical protection during winding and operation, contributes to the wire‘s smooth surface finish, and adds a secondary barrier against water ingress.

Dielectric Breakdown Voltage and Electrical Properties

The dielectric breakdown performance of the PE/PA construction is the critical parameter determining suitability for submersible motor operation. The insulation must withstand the applied voltage plus any transient overvoltages without failing, even after prolonged immersion in water.

PE/PA winding wire achieves a dielectric breakdown strength of 70 kV/mm when tested at 50 Hz and 20°C in accordance with DIN VDE 0303-21 . This value represents the minimum breakdown voltage per unit of insulation thickness. For a wire with 0.5 mm of PE insulation, this translates to a theoretical breakdown voltage of 35 kV, though actual working voltage ratings are substantially lower to provide appropriate safety margins.

The specific insulation resistance measures 10¹⁰ Ω·cm at 20°C per IEC 60093 . This high resistance ensures minimal leakage current even in water-filled motor environments where the insulation is continuously exposed to the surrounding fluid. The dielectric constant at 800 Hz is 2.3, measured according to DIN 53483 . This relatively low value indicates good insulating characteristics with minimal capacitive losses.

Voltage ratings for standard PE/PA constructions include 450/750 V for general-purpose submersible motors and up to 1,000 V for higher voltage applications . The long-term operating temperature should not exceed 70°C . The wire is designed to operate in water with a pH value of 6.5 to 8.5 .

Mechanical Properties and Aging Performance

The mechanical properties of PE/PA winding wire are specified to ensure the wire can withstand the stresses of winding without cracking or breaking. At 23°C, the minimum tensile strength is 10 N/mm² and minimum elongation at break is 100%, tested in accordance with IEC 60811-1-1 .

After aging at 80°C for seven days (7×24 hours), the wire maintains its mechanical integrity, with tensile strength remaining at or above 10 N/mm² and elongation at or above 100% . This aging performance demonstrates the long-term stability of the insulation system and its suitability for continuous operation at elevated temperatures.

Finished Product Testing

Every production batch undergoes comprehensive finished product testing to verify compliance with specification requirements. The testing protocols address the dimensional, electrical, and mechanical characteristics that determine the wire‘s fitness for submersible motor service.

Dimensional inspection verifies conductor diameter, insulation thickness, and overall wire diameter against specification tolerances. These measurements are performed on samples taken from each production lot to confirm that the manufacturing process maintains the required dimensional consistency.

Mechanical testing verifies tensile strength and elongation at break in accordance with the applicable test methods. The test procedures follow the methods specified in the IEC 60811 series for insulating and sheathing materials. The mechanical properties of the insulation are critical because the wire must survive the bending and handling stresses of motor winding operations.

Electrical testing includes insulation resistance measurement and breakdown voltage verification on finished wire samples. Test procedures follow the methods specified in IEC 60851-5, which specifies Test 13 for breakdown voltage and Test 14 for continuity of insulation . The breakdown voltage test applies increasing voltage across the insulation until failure occurs, with results compared against the minimum specified values.

Water resistance testing is particularly important for submersible applications. Finished wire samples are immersed in water at elevated temperature for extended periods, after which insulation resistance and breakdown voltage are re-measured to confirm that water exposure has not degraded the insulation system.

International Technical Standards

The manufacture and testing of PE/PA submersible winding wires is governed by a combination of national and international standards, with the specific applicable standard depending on the destination market and customer requirements.

The primary Chinese standard for this product category is the JB/T 4014 series, issued by the Ministry of Industry and Information Technology. Part 4 of this standard, JB/T 4014.4-2013, specifically addresses cross-linked polyethylene insulated nylon sheathed water-resistant winding wires with rated voltages up to 600/1000 V . The general requirements specified in JB/T 4014.1-2013 cover test methods, inspection rules, and packaging requirements for all parts of the series .

For the Indian market, the applicable standard is IS 8783, “Winding wires for submersible motors – Specification” . Part 4 Section 2 of this standard covers cross-linked polyethylene insulated and polyamide jacketed wires, providing an alternative certification pathway for customers in the Indian market . The Indian standard also specifies conductor data in Part 1 and materials for dielectric and jacket in Part 2 .

At the international level, IEC 60317-0-1 specifies general requirements for particular types of winding wires, including enamelled round copper wire. The test methods for winding wires are specified in the IEC 60851 series, which provides the procedures for determining electrical, mechanical, and thermal properties. For dielectric breakdown strength testing, DIN VDE 0303-21 provides the German standard for testing electric strength of solid insulating materials at power frequencies. For mechanical property testing of insulation and sheathing compounds, IEC 60811-501 specifies the procedure for determining tensile strength and elongation.

Application Scope

PE/PA winding wire is the preferred insulation for water-filled submersible motors, commonly known as “wet motors.” In these motors, the stator winding is directly exposed to the surrounding fluid, making the water resistance of the insulation system the single most important factor determining motor reliability and life.

The wire is used across a broad spectrum of submersible pump applications. In agricultural irrigation, deep well pumps must operate reliably for years with minimal maintenance access. In municipal water supply, submersible motors draw drinking water from aquifers. In industrial settings, these motors handle process water, cooling water, and wastewater. The wire‘s smooth surface finish of the polyamide sheath also facilitates automated winding processes, improving manufacturing efficiency . The construction is designed for AC rated voltage U0/U of 450/750 V water-filled submersible motors and similar conditions, with the ability to operate continuously in water at temperatures up to 70°C