22KV 50~2500KVA OIL-IMMERSED DISTRIBUTION TRANSFORMER

GENERAL DESCRIPTION

Pearl Electric produce oil filled distribution transformers for different applications, particularly for distribution and specific applications with the power up to 2500KVA.

TRANSFORMER FEATURE

• With off load tap changer and on load tap changer.

• The transformer windings are made of copper or aluminum with insulation material in class A or B.

• Channels in the windings guarantee oil circulation and windings optimal cooling.

• All transformers up to 3150 kVA are equipped with corrugated tank wall panels. Greater power units are fitted with bolt on radiators made with cold rolled and laminated steel. Customized tanks also available.

• All transformers can be filled with conservator tank for oil expansion if required.

• The tank is protected with water resistant coat (standard RAL 7031 or RAL 7033) with painting class from C3 up to C5-H.

TRANSFORMER MANUFACTURING TECHNOLOGY

• TRANSFORMER TANK

The transformer tank is available in two versions: corrugated (finned) tank or with radiators. All radiators are singularly tested before their assembling. If required, the transformer may be supplied with a traditional expansion conservator. All transformers up to 3150 kVA can be manufactured without conservator. The inside walls of tanks are protected, prior to sand blasting, with special paint insoluble to hot oil. The outside walls are protected with water resistant paint RAL 7031 or RAL7033 with painting thickness of at least 120 micron, suitable to the strictest environmental

• TRANSFORMER WINDINGS

The primary and secondary windings are made with electrolytic aluminum or copper, with insulation in pure cellulose paper or double enameled for wires of small diameter. These windings are oval or circular section and are a concentric type, coaxial to the core columns. The high voltage winding is made with a wire or a metal strip, helically wound with more layers or with continuous disc in relationship to the working voltage and the transformer's power. The low voltage windings are made with foil or strip and are equipped with terminal bars welded along the whole coil length in order to guarantee the correct sturdiness and electro-mechanical stress. Each winding layer of low and medium voltage is insulated with pure cellulose paper, the oil circulation and necessary cooling are assured by wide channels placed between the windings layers. Insulation between high and low voltage and between the latter and the core is made with compressed cardboard cylinders with a well-sized thickness.

• TRANSFORMER CORE

Magnetic cores are manufactured with cold rolled grain oriented magnetic sheet with high magnetic permeability and specific losses

The individual 45°cut sheets are manually assembled into cores using the "Step Lap" technique. Thus, especially good flux distribution at the joints is achieved resulting in exceptionally low losses and minimal no- load noise level.

The clawing is obtained with zinc frame core which are dimensioned in the best way to guarantee strength and static nature for all the movements during transportation and discharge, electric dynamic strain and the most difficult installations.

• TRANSFORMER BUSHINGS

The high and low voltage bushings are oil filled type in enameled brown porcelain according IEC standards. The insulators are fixed on the cover with special frames and may be substituted without removing the core and coil assembly. MV bushings can be equipped with arching horns and, upon request,with plug- in bushings.

TECHNICAL DATASHEET FOR 22KV OIL FILLED TRANSFORMER