Classification of Insulator Strings

Suspension insulator strings are only suitable for straight towers (or tension tower jumpers), single suspension insulator strings. Under normal operating conditions, it only bears the vertical and wind loads of the wires and additional loads. In the event of an accident, it must withstand the influence of wire tension. Therefore, the suspension insulator string meets both conditions simultaneously.
Due to different vertical loads, the suspension insulator strings of each phase may be assembled in different forms, such as single string, double string, or multiple strings. A single suspension insulator string is shown. The use of a single insulator string has many advantages: it requires fewer hardware and insulators, so the cost is lower; The corresponding damage rate is also lower, and the cost of replacement, maintenance, and repair is also reduced; Due to the proportional relationship between the probability of flashover and the number of insulators and strings, the number of insulators decreases, resulting in a decrease in the probability of flashover.
However, once a single insulator string is damaged, its reliability is very low. In general, double or multiple insulator strings can be used in places with large spans, severe stress, and important spans. Assembly diagram of double insulator string. After using double insulator strings, the string length increases and the tower height decreases by 0.3-1M. Therefore, single suspension insulator strings are generally used, and only when the vertical load is large and the strength of a single insulator string cannot be met, or at important spans, double or multiple insulator strings need to be used. Sometimes in mountainous areas, when the suspension angle cannot meet the requirements, double line clamps are also used.
The stress analysis of tension insulator strings is completely different from that of suspension insulator strings. Under normal working and operating conditions, suspension insulator strings only bear one vertical load and do not bear the surface tension of the conductor. On the contrary, tension insulator strings can mainly bear the tension of the entire living standard of the conductor.
Like suspension insulator strings, the selection method for suspension points should be determined after determining the number of insulator joints required for each insulator string. Due to the fact that the overlapping line point is the place where the stress of the insulator string is concentrated, a simple structure, flexible rotation, convenient construction, and clear stress overlapping line method should be selected. Because of this, although there are many ways to hang overhead transmission lines, there are mainly two ways to hang them, one is square, and the other is two. Both wire hanging methods can rotate freely up, down, left, and right, therefore, this wire hanging structure is not only suitable for changes in rotation angle, but also for the requirements of the downward inclination angle of the steel wire.
There are various types of V-shaped insulator assemblies available for editing and broadcasting. The use of V-shaped insulator strings has the following advantages: it can limit the oscillation of the insulator string, thereby reducing the size of the tower head; Reducing the width of tree cutting in forest areas and improving the excavation of slopes in mountainous areas in China can be achieved by reducing the tourism route corridor; Reduce the funds for corridor procurement during line construction and save investment.
On the other hand, using V-shaped insulator strings will double the requirements for insulators. Therefore, V-shaped insulator strings are generally used for tower windows and are limited to medium phase conductors of wine cup, door, and cat head types. If used in the side phase, the lateral arm of the side phase is extended, but it is not economical. Therefore, a comprehensive technical and economic comparison was conducted before using the V-shaped insulator string. V-shaped insulator strings are more suitable for retrofitting old lines or boosting lines.