Insulating Sleeve Types and Related Products

Type Single insulating sleeve Wall sleeves are made with pure porcelain or resin used for 35 kv and below voltage levels, of which the insulating part is tubular, flange is card installed or adhesive bound to be easily fixed on the perforated wall.……


Single insulating sleeve

Wall sleeves are made with pure porcelain or resin used for 35 kv and below voltage levels, of which the insulating part is tubular, flange is card installed or adhesive bound to be easily fixed on the perforated wall. Flanges are usually gray cast iron, and when the working current is greater than 1500, non-magnetic materials are often used to reduce heat. The insulation structure of single insulating sleeve is divided into two types: air cavity and air cavity short circuit. The air cavity sleeve is used for the voltage grade of 10 kv or below. There is an air cavity between the conductor and the porcelain sheel as auxiliary insulation, which can reduce the sleeve capacitance and improve the corona voltage and the sliding lightning pressure. When the voltage level is higher (20~30 kv), a corona will occur inside the air cavity and the above effect will be invalidated. The inner porcelain sheel of the porcelain sleeve is coated with semiconducting glaze, and the air cavity is short-circuited by connecting a spring film with the conductor to eliminate the internal corona. But corona and glitter can still occur near the flange. Usually, a large umbrella skirt is arranged on both sides of the porcelain sheel around the flange, coated with a semi-conductive layer to distribute the electric field evenly and improve the discharge characteristics of the sleeve.

Composite insulating sleeve

Transformer bushing or circuit breaker sleeve is made with oil or gas as insulating medium used for voltage rating of 35 kv. The inner cavity of the composite insulating sleeve is filled with transformer oil, which acts as a radial insulation. When the voltage is over 35 kv, the insulation is reinforced by adding insulating tube or cable wire to the conductor. The conductor structure of composite insulating sleeve has two types: draw lead and guide. The draw lead uses the outlet cable of the transformer through the sleeve, and the installation is convenient. When the working current is greater than 600A, the cable structure is difficult to install, and the guide structure is generally adopted. The capacitance type sleeve consists of a capacitor, a porcelain sheel, a metal accessory and a conductor, mainly used for ultra high voltage transformers and circuit breakers. The upper part is working in the atmosphere and the lower part is working in the tank. The capacitor core of the capacitive sleeve is used as the inner insulation, and the porcelain sleeve acts as the outer insulator, which also protect the capacitor core. The electric field on the surface of porcelain sleeve is evenly distributed by the pressure of the internal capacitor core, thus improving the electrical insulation performance of the sleeve. Metal accessories have intermediate connection sleeve (flange), end cover, all pressure ball, etc. The conductor is cable or hard steel pipe.

insulating sleeve

Condenser bushing

When capacitance core is made of gummed paper, it has high mechanical strength, good moisture resistance, and can be installed from any angle. Its structure and maintenance is simple, without sleeve, and the core can be turned into short tail type to reduce its size. The disadvantage is that at the high voltage level, the insulating material and the process requirements are higher, the inner core is not easy to eliminate the air gap, so that the partial discharge voltage is depressed. Due to the high dielectric loss and low discharge voltage, the resin-bonded paper type has been replaced by the oil paper type. When using the oil paper as the capacitor core, there is usually down porcelain sheel, and the lower part is bigger, which is sensitive to humidity and  has high sealing requirement; the advantages are that the insulation materials and process are easy to solve, the dielectric loss is small, the partial discharge performance is good. Since the 1970s, China has been widely used oil paper capacitive sleeves of 110~500 kv ultra-high pressure. In the 1980s, China also developed the rubber impregnated paper sleeve. After the capacitor core was rolled by insulating paper, it was impregnated with synthetic resin and then cured. Its performance has both the advantages of the adhesive paper and the oil paper capacitor sleeve.

Related products

K-B thermal shrinkable busbar protection sleeve is made of high quality polymer and environmental flame retardant. It is widely used in the protection of the busbar inside the switchgear and outdoor busbar. It has the following advantages: prevent short circuit faults caused by rodents, snakes and other small animals; prevent the corrosion of chemical substances such as acid, alkali and salt on busbar; protect the maintenance personnel from accidental injury caused by strayed into the charging zone; adapt to the development trend of the miniaturization of switch cabinet, and solve the problem of interphase insulation of the busbar.

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