Needle Insulator P-20T

Product Description and Usage Instructions:

P, PQ High-Voltage Line Pin-Type Porcelain Insulators

I. Overview

Needle-type insulators are an older type of insulator used in high-voltage transmission and distribution lines. Due to their simple manufacturing, low cost, easy installation, and ability to reduce tower height (since the insulators are installed vertically with the grounding part at the bottom), they are widely used in overhead power lines with a rated voltage of 6 to 35 kV and a frequency of 100 Hz in ordinary and polluted areas for three-phase power systems, serving as insulation and support for conductors.

The needle-type insulator is composed of an insulating component and a steel foot, which is a rigid insulator that rigidly mounts the insulating component to the supporting structure using a steel foot fixed within the insulator. The insulator can be made up of a single piece or multiple interconnected insulating components. The insulating components of the porcelain insulator are porcelain pieces, typically glazed in brown or white. The fixation of the porcelain pieces and the foot can be separable or permanent (needle-type insulators with adhesive feet).

Insulators are categorized by structure into two types: glue-mounted and zinc-threaded connection. The glue-mounted type connects the porcelain piece directly to the base with cement, featuring a deep groove in the porcelain piece where the steel base is inserted to prevent loosening, and an elastic pad is placed between the steel base and porcelain piece. The zinc-threaded connection type involves first cementing a zinc threaded sleeve into the porcelain piece's inner hole, and then connecting the sleeve to the steel base via the threads. The zinc threaded sleeve serves as a shock absorber and facilitates the replacement of the porcelain piece. There are also types that use mechanical connections via porcelain threads.

The old model needle-type porcelain insulators specified in GB1000-1981 standard are divided into five levels according to rated voltage: 6, 10, 15, 20, and 35kV. Each type is further divided into two specifications based on the steel foot design: iron pole straight foot and wood pole straight foot.

The new model needle-type porcelain insulators specified in GB/T1000.2-1988 standard have a rated voltage of 10kV, and are categorized into three types based on applicable environmental conditions: General Type, Reinforced Insulation Type 1 (Medium Pollution), and Reinforced Insulation Type 2 (Heavy Pollution).

To mitigate radio interference, edge glaze insulators are also provided, which have upper conductive glaze above the side slots and are marked with the letter "B" in the model.