Views: 0 Author: Site Editor Publish Time: 2025-07-28 Origin: Site
Insulating tubes play a critical role in power transformers by ensuring electrical isolation, mechanical protection, and reliable long-term performance. These components are selected to withstand operating temperatures, electrical stresses, and environmental factors unique to each transformer design. This article delves into the main categories of insulating tubes, their placement within the transformer assembly, and the advantages they confer.
Applications: Terminal ends of windings, low-voltage leads, and connector covers.
Temperature Rating: Up to 105 °C.
Advantages: Economical, easy to cut and install, good resistance to oils and ozone, and acceptable mechanical flexibility.
Applications: Insulating and sealing winding leads, branch connections, and transition joints.
Temperature Rating: 90–135 °C.
Advantages: Shrinks uniformly upon heating, creating a tight fit around conductors. Provides both insulation and environmental sealing, preventing moisture ingress.
Applications: Support pillars, internal bushings, and through‑wall insulators in medium‑ and high‑voltage transformers.
Temperature Rating: 155–180 °C.
Advantages: High mechanical strength, excellent dimensional stability, resistance to oil immersion, vibration, and electrical tracking.
Applications: Spacers between winding layers, coil interleaves, and inner liners of porcelain bushings.
Temperature Rating: Up to 155 °C.
Advantages: Low dielectric loss, high thermal stability, moisture resistance, and minimal thickness, ideal for compact designs.
Applications: Custom‑shaped supports, lead‑through tubes, and mounting posts.
Temperature Rating: 130–160 °C.
Advantages: Excellent strength‑to‑weight ratio, customizable forms, and resistance to corrosive environments.
Applications: High‑frequency transformers, pulse‑power units, and precision measurement coils.
Temperature Rating: 200–260 °C.
Advantages: Ultra‑low dielectric constant, near‑zero dielectric loss, outstanding chemical inertness, and wide temperature tolerance.
Applications: High‑temperature coil supports, sensor housings within windings, and narrow‑gap insulators.
Temperature Rating: Above 200 °C.
Advantages: Exceptional thermal and radiation resistance, superior electrical integrity in confined spaces.
Applications: Critical high‑temperature spots and localized high‑voltage paths.
Temperature Rating: Up to 250 °C+.
Advantages: Superior mechanical strength, long-term dimensional stability, and excellent chemical resistance—albeit at higher cost.
Applications: External high‑voltage bushings, interface between transformer tank and overhead conductors.
Temperature Rating: Effectively unlimited for electrical purposes; mechanical limits vary by design.
Advantages: Outstanding dielectric strength, resistance to weathering, arc resistance, and minimal maintenance over decades.
Applications: Ultra‑high‑voltage experimental transformers and VHF/UHF transformer prototypes.
Temperature Rating: Beyond 1,000 °C.
Advantages: Exceptional thermal stability, extremely high breakdown voltage, but higher manufacturing complexity.
| Material Category | Temp. Range (°C) | Dielectric Strength (kV/mm) | Key Pros |
| Thermoplastics (PVC, PE) | 70–135 | 10–20 | Low cost, easy processing |
| Thermosets & Composites | 120–180 | 15–30 | High strength, moisture and oil resistant |
| Engineering Polymers (PTFE, PI, PEEK) | 200–260+ | 20–40 | Ultra‑low loss, high‑temp stability |
| Ceramics & Oxides | 300–1,000+ | 30–60 | Superior dielectric and aging resistance |
Voltage Level:
Higher voltages demand materials with greater dielectric strength. For low-voltage leads, PVC or polyolefin suffices; for bushings at hundreds of kilovolts, porcelain or epoxy‑fiberglass is preferred.
Thermal Environment:
Ambient and hotspot temperatures inside a transformer guide the temperature rating. Standard oil‑immersed transformers often use materials rated up to 155 °C, whereas special high-temperature applications call for PTFE, PI, or ceramics.
Mechanical and Chemical Stressors:
Vibration, oil immersion, gas exposure, and mechanical loads influence material selection. Epoxy‑fiberglass and FRP excel under vibration and oil, whereas PTFE and PEEK withstand chemical attack.
Installation and Cost Considerations:
Thermoplastics require minimal tooling and enable fast assembly. Conversely, high-performance polymers and ceramics involve more complex processing and higher unit costs but deliver superior longevity in demanding applications.
Insulating tubes are vital components that ensure the safe, efficient, and reliable operation of power transformers—from economical PVC and heat‑shrink options for low‑voltage connections to high‑temperature PTFE and robust ceramic bushings in ultra‑high‑voltage equipment—and by understanding the electrical, thermal, mechanical, and chemical requirements of different transformer sections, manufacturers can balance performance, durability, and cost in every design; at Welldone Power, we have continually supplied these essential insulating tubes to meet their exacting standards.
