Yes Tom ..   
      
      
    TW> The ones I am thinking about have NO switchingy. They run all the time   
    TW> on the battery and the function of the line power is only for battery   
    TW> charging. So NO frequency matching is not needed when line power is   
    TW> restored.   
      
   True.  But also be careful about one other thingee!  The good UPS stuff does   
   use sine wave AC output.  However, some of these, per my recall, use   
   triangular wave form output.  Or was it square wave form output?.  Been a long   
   time back, can't be sure I've got this exact.  I forgot to mention that in my   
   original post(age) here.  Age creeps into even postal work!   
      
   But at least this isn't as bad as the longest it has ever taken me to get a   
   real reply from a letter I mailed overseas from my USPO mail box. I never got   
   a reply until THIRTY-FIVE years later!  Was stunned when that reply letter was   
   posted for real to me and the gentleman I had originally written to was never   
   delivered my original letter until 35 years later - when he then replied to me!   
      
   All my current UPS units are at least 600 watt units that are relay rack   
   mounted stuff.   
      
      
   Mike Luther N117C at 1:117/100   
      
      
      
   ---   
    * Origin: BV HUB CLL(979)696-3600 (1:117/100)