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Nuova Via di Piano Comprensorio Vulcano 

Sesto San Giovanni, MI 20099 Italy 

Tel. 02-24105.001 

 

IS 2653 GB

 

Page 

6

 of 

18

 

 

 
3.3 

Storage conditions 

 
The bushings when are not in service have to be store indoor (above -5° degree C); especially in extreme 
weather condition (+40° to -40/50°) it is forbidden to store them outside even for a short period (mandatory to 
fulfil warranty conditions). 
 
It  is  necessary  that  all  the  crate  is  placed  inside  a  suitable  warehouse  and  that  a  periodical  check  of  the 
bushing,  the  gas  pressure  and  of  relevant  accessories  is  activated  (see  Chapter  5.1).  The  recommended 
timing is six months. 

Technical characteristics 

 

PWS  and  PWHS  bushings  are  based  on  gas  technology  (pure  SF6  or  SF6-N2 mixture). The electric field is 
controlled by suitable electrodes that are placed inside and outside the bushing. The internal electrical strength 
capability  is  ensured  by  the  gas  density,  while  the  external  withstand  capability  is  ensured  by  composite 
insulators of adequate length and creepage distance. 
 
The  bushing  is  made  by  two  sections,  the  indoor  and  the  outdoor  side,  that  are  designed  to  withstand  the 
different environmental conditions present inside and outside the valve building. 
 
The bushing is designed and tested in accordance with the IEC 62199 and IEC 60137 standard. 
 
Each section is based on: 

 

  A composite insulator with silicone sheds. 

  The internal shielding arrangement. 

  An internal aluminium tube conductor. 

  The top flange with the line terminal. 

  The top toroidal electrical shield. 

 
The two sections joined by the central flange make the complete bushing. 
The  sealing  joints  between  the  parts  are  designed  to  minimize  the  risk  of  gas  leaking  by  using  the  double 
gasket concept. This means that the sealing is ensured by two concentric ‘O ring’ gaskets placed in separate 
grooves. 
 
The bushing is designed in accordance to the customer requests with different environmental conditions and it 
can operate at low temperatures down to -50° C when filled with pure SF6 gas. 
 
The solution based on gas technology offers the following advantages: 
 

  Simple design. 

  Lower mass compared with equivalent solution based on solid insulation. This means less risks in case 

of earthquake. 

  Less different materials that reduces the risks due to DC and PR stresses. 

  No aging of the main (gas SF6 or SF6 N2 mixture) internal insulation. 

  Fast production and delivery time. 

  Full dry explosion-proof solution. 

  Limited  maintenance  and  possibility  for  on  line  monitoring of the main insulation through gas pressure 

control (i.e. density control). 

 
 
The bushing can be installed on the wall with different angles from the horizontal, as previously agreed.

 

 
 
 
 

Содержание PWS

Страница 1: ...any name udated 07 07 2016 AF LP 3 Storage and transport conditions updated 22 08 2016 AF LP IS 2653 GB GE Proprietary Information Class III Confidential Export Controlled U S Government approval is r...

Страница 2: ...3 Storage conditions 6 4 Technical characteristics 6 5 Bushing preparation and installation 7 5 1 Controls at the arrival 7 5 2 Bushing unpacking 8 6 Gas SF6 characteristics and gas filling instructi...

Страница 3: ...oltages above 1000V 2 Safety In this document important safety requirements are highlighted by the word CAUTION and important operative instructions are evidenced by the word NOTE This manual must be...

Страница 4: ...ersonnel involved in wall bushing assembly All problems detected during the bushing installation must be reported to the Foreman and to GE Grid Solutions RPV Supervisor The bushing is a pressurized de...

Страница 5: ...nt of the crate during the transport it is responsibility of the transport company to carefully fix it on the vehicle by suitable retain systems like ropes synthetic pulling bands or any other method...

Страница 6: ...ed and tested in accordance with the IEC 62199 and IEC 60137 standard Each section is based on A composite insulator with silicone sheds The internal shielding arrangement An internal aluminium tube c...

Страница 7: ...the arrival Before proceeding with the unpacking operation it is necessary to perform the following controls Check the wooden crate status Check the external visual impact recorder s Open the crate a...

Страница 8: ...upports and it is locked by locking belts Additional intermediate belts support the composite insulator to a wooden structure Figure 4 Bushing crate inside view Figure 5 Bushing inside the crate top v...

Страница 9: ...ow the steps indicated into the provided erection and installation manual IS 2654 GB Figure 7 Example of bushing extraction and lifting CAUTION The two composite insulators are protected by a PE plast...

Страница 10: ...ium Supplier The minimum requirement is that the characteristics will be in accordance with the data listed in the GE RPV limits column The gas filling must be performed with an equipment that prevent...

Страница 11: ...e up to 0 2 MPa abs 1 bar gauge Pressure must be directly measured on the gas density monitors installed on the bushing flange Check all the gas seals for leakages with a suitable SF6 leak meter devic...

Страница 12: ...the DILO machine check that the machine set up is for gas filling and that the connecting pipe is full of SF6 In the case of direct filling from the bottle check that the bottle is effectively charged...

Страница 13: ...ation on the scale is expressed in MPa absolute referred to a gas temperature of 20 C This means that the instrument converts the gas density into a value of pressure referred to 20 C independently fo...

Страница 14: ...pair procedure is described into the component manual see reference in the summary prepared for the specific wall bushing The composite manufacturer can provide a repairing kit and also a technical su...

Страница 15: ...the camera must be properly set in order to avoid false signals and background noise In addition an infrared scan on the line terminal and the incoming cables can reveal incipient hot spots phenomenon...

Страница 16: ...Gas valves electrical equipment and connecting cables When plant is off Clean the cubicle Check for gas leaks Check functionality of pressure gauge and DILO Type valves Check terminal blocks wiring ca...

Страница 17: ...ect the closure cap and the fixing screws CAUTION Do not remove the closure cap and do not touch the disk when the bushing is filled with gas An explosion of the disk could be very dangerous Gas densi...

Страница 18: ...lectric terminals Copper silvered Dismount and recycle Toroids Aluminium Dismount and recycle Internal electrostatic shields Aluminium Dismount and recycle Transport supports Aluminium Recycle the alu...

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