
TR A N S FOR M E R BUS H I NG S T YPE G S B 8 0 0
I N S TA L L AT I O N A N D M A I N T EN A N C E G U I D E
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The GSB bushings are basically maintenance free; no regular
maintenance is needed.
WARNING
No work can be performed on the bushing while
energized. Before starting any work, the bushing
must be grounded.
3.1 Recommended maintenance and inspections
1. Cleaning of insulator surfaces
2. Measurement of capacitance and tan
d
3. Thermo vision (infrared camera) check for local
overheating of connectors
4. Check for leakage
3.1.1 Cleaning of insulator surfaces
Avoid solvent coming in contact with the bushing
gasket and porcelain joints.
Composite:
Under conditions with extreme pollution it may
be necessary to clean the silicone rubber insulator surface.
This should be done by wiping with a moist cloth. If
necessary, ethyl-alcohol or ethyl-acetate may be used.
Trichloroethane or methylchloride are not recommended.
3.1.2 Measurement of capacitance and tan
d
Please refer to Section 2.15.3 Measurement of capacitance
and tan
d
.
3.1.3 Thermo vision (infrared camera) check for local over-
heating of connectors
At maximum rated current the outer terminal of the bushing
reaches a temperature of 35 to 45°C above the ambient air
temperature. Significantly higher temperature can be a sign
of bad connections, especially at lower current loads.
3.1.4 Check for leakage
Make a visual inspection for oil leakage between the bushing
and transformer flange during normal station inspections.
3.2 Disposal after end of service life
The GSB bushing is delivered in a wooden crate with a
stainless steel sealing tube for moisture protection. The
bushing consists of the following:
The composite insulator consists of silicone rubber on a
tube of fiberglass-reinforced epoxy. Between the insulator
and condenser core, there is silicone gel.
The resin-impregnated paper (RIP) condenser core consists
mainly of epoxy, crepe paper and an embedded conductor
tube in copper. The core also contains a smaller amount of
aluminum foil inserts, rubber-bonded cork, rubber sealings,
braided copper wire (tinned), braided copper straps, silver
glue and lead. By crushing the core, the conductor tube can
be separated and sorted while the rest of the core can be
incinerated in a suitable furnace.
The removable flange is made of cast aluminum, the bolts of
stainless steel and the gaskets of rubber. The gaskets in the
flange are easily removed.
Removable voltage tap containing a tap body in epoxy, tap
cover in aluminum, cable, contacts in brass and gaskets. By
crushing the body of the voltage tap, the embedded brass
contact stud can be separated.
The flange is filled with approximately 2 deciliters of silicone
gel. When the flange is separated from the condenser core
the gel can be scraped out and separated.
The outer terminal is either copper or aluminum, which may
be coated. The coating material can vary due to special
requests from the customer. The stainless steel bolts and
rubber gaskets can be easily separated.
The draw-rod contains parts made of steel, brass and nylon.
The bottom contact is pure copper.
The end-shield is epoxy-coated aluminum.
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3. Maintenance