Application of phenolic cotton cloth rod in transformer

Phenolic cotton rods (also known as phenolic laminated rods or bakelite rods) are a common insulating structural mate...

Phenolic cotton rods (also known as phenolic laminated rods or bakelite rods) are a common insulating structural material in transformers, primarily used to manufacture support, fastening, and isolation components requiring high mechanical strength, good insulation properties, and a certain degree of dimensional stability.

The following details its application and selection key points in transformers:

I. Main Application Scenarios

Coil Stays:

Purpose: Provides support within the coil (axial oil passages) or between coils (radial oil passages), forming cooling oil channels, ensuring coil structural stability and preventing deformation.

Requirements: High mechanical strength (compression and bending resistance), excellent electrical insulation properties, dimensional stability, and resistance to transformer oil and heat.

Advantages of Phenolic Cotton Rods: Their laminated structure provides excellent mechanical strength and rigidity, making them a classic material for stays.

Spacers/Spacers:

Purpose: Used to support, secure, and isolate components such as coils, core clamps, and leads, maintaining electrical clearance and creepage distances between components. Requirements: Good mechanical strength, insulation, processability, wear resistance, and heat resistance.

Advantages of Phenolic Cotton Rods: Easy to process into various complex shapes (turning, milling, drilling), high strength, and reliable insulation.

Fasteners (screws, nuts, pins, etc.):

Purpose: Used to secure components such as clamps, pressure plates, and tap changers.

Requirements: High mechanical strength (especially shear and tensile strength), good insulation (to avoid short-circuiting loops or reduced insulation distances), and creep resistance.
Advantages of Phenolic Cotton Rods: Significantly stronger than ordinary plastics, with excellent insulation properties, they can replace some metal fasteners to eliminate eddy current losses or meet insulation requirements.

Lead Supports/Clamps:

Purpose: Support, secure, and guide high and low voltage leads, ensuring accurate lead positioning, adequate insulation distances, and preventing vibration wear.

Requirements: Good mechanical strength, insulation, heat resistance, and arc resistance (when near high voltage areas). Advantages of Phenolic Cotton Rods: They can be processed into desired bracket shapes, meeting required strength and insulation performance.

Tap Changer Components:

Purpose: Used in manufacturing insulating brackets, connecting rods, contact supports, and other components of tap changers.
Requirements: High mechanical strength, excellent electrical insulation, wear resistance, dimensional stability, and arc resistance.
Advantages of Phenolic Cotton Rods: They offer excellent overall performance and are a commonly used insulating structural material in traditional tap changers.

II. Selection Guidelines

III. Selection Principles

Mechanical Strength Priority: For large-capacity, high-current transformers, choose larger-diameter, high-strength rods.

Reliable Electrical Performance: For high-voltage applications, select rods with low water absorption and high arc resistance.

Machining Suitability: For components requiring threading or turning, choose rods with better toughness to avoid cracking during processing.

Environmental Adaptability: For oil-immersed transformers, select rods with heat resistance ≥ Class B or Class H; for humid environments, use moisture-resistant types.

Summary

Phenolic cotton cloth rods in transformers provide both insulation and mechanical load-bearing capacity, making them ideal for fastening, supporting, and wear-resistant applications. Proper selection should comprehensively consider mechanical load, electrical requirements, and operating environment to ensure safe and reliable transformer operation.