ABB GSB 245 Technisch handboek - Pagina 14

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1. Standards

T R A N S F O R M E R B U S H I N G S T Y P E G S B T E C H N I C A L G U I D E

Draw rod system

The draw rod system offers the following advantages

compared to other methods used for high currents:

• No manholes required in the transformer tank.

• The bushing tube is used as a conductor.

• No special supports required in the transformer, as is the

case with plug contacts.

• Perfect guiding of the bushing into the transformer.

The center tube of the bushing is used as conductor. The

transformer leads are fitted with cable lugs, bolted to a

bottom contact. This contact is tightened to the lower end

of the bushing tube by a steel draw rod. The upper end of

this rod is bolted to a spring device, which consists of two

concentric tubes of different materials, designed to give the

required contact load at all temperatures. The draw rod is

divided into two parts at level with the flange. The lower

draw rod includes bottom contact, guide cone, rod and joint.

The upper draw rod consists of compensating device, rods,

joints, washer and nut.

Threaded

hole M8 for

pulling wire

Additional

joint on

request

min 200

64 45

—

09 Draw rod system.

∅152.5

125

Bottom contact type 1

M12 (4x)

(standard)

If required to meet the transport conditions, an additional

joint can be positioned at any desired level below the flange.

This must be stated in the order. The lower part with contact

and end-shield can then be secured to the transport cover

during transport and storage of the transformer.

Bottom contacts with 4 threaded holes for cable lugs are

available. The bottom contacts are made of copper in one

piece. There are standard end-shields for type 1 bottom

contacts available; see Standard end shield and Table 8. The

type 2 bottom contact is intended to use with customized

shields, using three M10 holes at diameter 125 mm for shield

assembly. Special bottom contacts are available on request.

—

Table 7. Draw rod system.

Cat. No.

Type of draw rod

1ZSC999006

Lower draw rod

1ZSC999007

Upper draw rod

Bottom contact type 2

(only for customized end-shields

and draw rod)