Saturday, June 8, 2019

Cable insulators

Previously mentioned in the previous section on the classification of cables according to the type of insulation, and mentioned there are three of the most famous types of cable insulators are PVC polyvinyl chloride, polyethylene yarns XLPE, and rubber condoms and to complement the benefit, we refer here to other materials used in insulation cables and conductors such as:

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A - Insulating oil: Insulating oil is one of the most important electrical insulators used in transformers, cables and cutters. In order to be able to rely on oil as a good insulator, there must be several conditions including that the oil is a high degree of purity, because the presence of impurities helps to collapse the oil insulation, The humidity in the oil is minimal, because increasing the humidity helps to break the oil insulation and the high temperature leads to a decrease in the value of the effort required for the collapse of the oil insulation and the high temperature lead to the low value of the effort required for the collapse of oil isolation and the collapse effort of oil ranging from KV / cm (120 70) This means that the highest effort of the collapse of the air, which equals only.

B - Adhesive insulating varnishes: These materials are of great importance in the electrical industries, especially in the manufacture of semantics and devices and the most important benefits that give a long life for other insulation materials, and protect the insulation materials and files from moisture and reduce the cohesion of dust and dust with exposed files.

Mineral Insulation: This type of condensation is made of magnesium oxide powder and is used in high temperature environments where it has high resistance to fire.

Measuring insulation of cables

The insulator bearing of electrical stress without breaking down is an important feature of insulation, which should be considered in many applications.

(E) in which the insulation breaks down. If the insulator has a thickness of (d) meters and the voltage between the terminals at the collapse is (V) volts, the maximum value of the load Insulation of electrical strength of insulation Dielectric Strength.

The electrical strength of the insulation is also measured by another value called Impulse Strength, which expresses insulation tolerance for high-altitude but very short-lived experiments. It occurs in scientific reality at switching moments or lightning.

One of the most important tests on cables is the isolation test where the cable is tested under a high voltage specified by the specification to ensure the safety and quality of the insulation before the cable is released as will be explained in detail in the last chapter of this book.

Classification of Insulators

Insulation materials for different temperatures are considered important properties in the classification of electrical insulators. For this reason, insulation materials are divided into seven categories, each of which is used up to a certain temperature as stated in the specifications of the International Society of Engineers.

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