63942ec6   
   From: phil_a@tpg.com.au   
      
   "Nutcase Troll"   
      
   I tested a pile of brand new mains TFs several years ago at either 1kV   
   or 1.5kV, over 50% failed. They all passed 500v testing.   
      
      
   ** None of them would pass the 1 minute flash test standard of 4kV AC.   
      
   Unfortunately there are also a minority of new transformers with   
   barely functional insulation too. Easy to spot though, no bobbin or   
   other visible insulation.   
      
   ** Really ???   
      
   Transformer life expectancy depends on temperature,   
      
   **There is a point where the enamel on the wire softens, but otherwise life   
   span depends on good construction techniques, good enamel on the wire and   
   operation in a dry environment.   
      
   BTW:   
      
   I have seen a batch of 400VA trannys fail after some years due to self   
   adhesive insulation tape -  the yellow stuff you see all used the time   
      
   The tape had been ( mistakenly ? ) laid in direct contact with the windings   
   allowing the adhesive to eat through the enamel and cause shorted turns.   
      
      
   ...   Phil   
      
   --- SoupGate-Win32 v1.05   
    * Origin: you cannot sedate... all the things you hate (1:229/2)