Hi everyone, this is my first post and I have a question. 
Are these standalone systems sensitive to harmonics in the power line? 
I'm asking this because I've installed this model on a gas station whit no UPS, and no stable power supply, and every single day I have some new trouble with this equipoment. At first I thought it was a bad DVR, and swaped it for a new one. It keeps switching on and off, and now it shows "no valid hdd". 
  
All I can think is "there's something wrong with power line". 
  
Am I wrong or an UPS is a "MUST" on these situations?