International Electrotechnical Commission <br/><br/>
IEC: 62271 - 20(Ed-2.0) - 2011 - 09; high - voltage switchgear and controlgear - part 203 : gas-insulated metal - enclosed switchgear for rated voltage above 52 kv 

 - Geneva  IEC  2011 
 - 158 
<br/><br/> Downloaded from IEC website 
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