1

GRID

PGFECondenser Bushings

bushings

Customer Benefits• Even voltage distribution

across the bushing thanks to the capacitance-graded condenser core.

• No deterioration of grounded part for CT installation real-ized internally and protected by porcelain.

• Belleville washers to absorb conductor dilatation and vibrations in service.

• Installation in any position.

Manufacturing of the bushing

The main electrical insulation is provided by a condenser body made of a continuous sheet of pure kraft paper bonded with pre-polymerised epoxy resin and wound around a tube or conductor rod.

During winding, a series of cylindrical semi-conducting foils made of graphite printed paper are inserted coaxially between the layers of paper. These foils assure the best possible distribution of the radial and longitudinal electrical gradient between the conductor and the fixing flange, which is grounded. Winding is computer-controlled, the final shape is ob-tained by subsequent machining on a lathe.

After winding, the bushing is placed in an oven for final polymerization of the resin.

Depending on the overall dimensions of the bushing, when the gradients are very low, the insulation can be achieved directly by a tube impregnated in epoxy resin and reinforced by a fiber glass filament winding.

AN ALSTOM COMPANY

Design, components and manufacturing tech-nology guarantee an average life time of over 40 years under normal operating conditions.

The bushing is designated as follows:PGFE.24.125.25000 P Condenser bushings

(“P” from the Italian word “Passante”) G Power generator F High current application (force cooled) E Epoxy resin bonded paper (ERBP)

24 Rated voltage in kV

125 BIL class in kV

25000 Rated current in A

Epoxy resin bonded paper for AC generators

PGFE are bushings designed for use on AC power generators. The dielectricinsulation is achieved by a capacitance-grade condenser body, for installation in any position.

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CoNDENsER BusHINgs PGFE

Condenser bushings

Rated voltages up to 30 kV

outer envelopes: Porcelain and/or Fiberglass tube

Cooling: Natural, hydrogen, water

Coupling by means of a Belleville washer placed on the air side

Inner conductor made of aluminum or copper casting

Dry filling (polyurethane foam) of the space between the porcelain and condenser body

Installation in any position

CT accommodation on request

Flange made of aluminum or stainless steel, low permeability

Maximum current rating up to 45,000 A

All o-ring gaskets, FPM material: elastomer

Fig. 1(24 kV - 9,000 A)

Fig. 2(24 kV - 12,000 A)

Fig. 3(24 kV - 25,000 A)

Fig. 4(24 kV - 25,000 A)

Fig. 5(24 kV - 20,000 A)

Fig. 7(20 kV - 10 kA)

Fig. 6(24 kV - 25,000 A)

33

CoNDENsER BusHINgs PGFE

The most common solutions and their respective maximum current ratings are:

Natural cooling up to about 10,000/12,000 A

Forced hydrogen cooling up to about 25,000 A

Forced water cooling up to about 45,000 A

All bushings are tested and have electrical and mechanical characteristics that comply with the main standards:

IEC 60137 “Bushings for alternating voltage above 1000 V”

ANsI/IEEE C57.19

Din 48123

The prevailing technical specification in the field of AC power generators (general Electric, siemens-Westinghouse, Mitsubishi, Alstom-ABB, ect.).

Test

Envelope

For outdoor application, the air side envelope is made of brown porcelain, with a creepage distance for very highly polluted atmospheres (31 mm/kV).

For indoor application, the air side envelope is made of porcelain or a tube impregnated in epoxy resin and reinforced by a fiber glass filament winding. The hydrogen side envelope can be made of porcelain or fila-ment winding tube.

Flange

The flange is made of low-permeability, stainless steel casting. It is made of aluminum only for low current ratings (natural cooling applications).

Gaskets

The o-ring type gaskets are made of FPM. They are compatible with the fluids they are in contact with. Air side, the gaskets are sealed to protect them effectively from polluting weather conditions.

Assembling

The porcelain and metal parts (top fixing plate, flange and bottom fixing plate) are coupled by means of springs, generally Belleville washer type springs, placed in the air side of the bushing. The Belleville washers are very effective against the vibration and impact load stress caused by the normal service of the bushing installed on the power generator.

The air and hydrogen side envelopes consist of two completely separate parts, and the flange is fixed between them. This design avoids any pos-sible movement of the flange during the life time of the bushing.

The space between the porcelain and condenser body is filled with dry insulating material (no fluids are used).

Current Rating

The PgFE bushing has been designed to satisfy any requirement in terms of current ratings and cooling method.

The inner conductor is made of an aluminum or copper tube.

44

CoNDENsER BusHINgs PGFE

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GRID

Alstom Grid Worldwide Contact Centre www.grid.alstom.com/contactcentreTel.: +44 (0) 1785 250 070 www.grid.alstom.com

To contact the manufacturerViale suzzani, 229 20162 MILANo (Italy)Tel.: +39 02 661 221Fax: +39 02 647 09 06Email: rpv@alstom.com

Following the acquisition of PAssoNI & VILLA, ALsToM gRID now offers a large portfolio of condenser bushings for AC or DC operation. If you require any further information, please address your queries to

rpv@alstom.com AN ALSTOM COMPANY

Nameplate

Each bushing is provided with a nameplate with all the electrical data and serial number, in accordance with the requirements of IEC standards and the customer’s technical requirements. The plate is made of stainless steel and is affixed to the flange by nails. The plate indicates:

MILANITALY

MILANITALY

1

2 3 4

P G F E - 2 2 50 - 11 0 0 0 0 N .

2 0 k V 0 01 0 A0 6 0 k g *

5

6

Alstom Grid can satisfy any special test requirements such as:

Mechanical impact load test Vibration test Equivalent thermal test with or without cooling simulation Inside pressure test at any pressure level Leakage test, including by leak meter Drop flow rate

1. Type of bushing2. Insulating voltage3. Rated current4. Weight5. serial number6. Month and year of production