Mains and UPS

Replies

• 

  Ramani Aswath

  mreccentric

  When my computer runs on UPS, there is a some continues noise that comes from the speaker, even if it is not plugged to any audio. It works perfectly when it runs on Mains, why this happens?

  If a true UPS (Uninteruupted Power Supply) is connected, then the computer is ALWAYS on UPS. If an inverter is used it is possible that a hum from wave form distortion gets into the act.
  
  Bioramani
• 

  ABCD ABCD

  hi bioramani,
  can please elaborate the part:

  ' is used it is possible that a hum from wave form distortion gets into the act'

• 

  Ramani Aswath

  mreccentric

  hi bioramani,
  can please elaborate the part:

  The out put wave form of most commercial inverters is not a true sine wave. This generates other frequencies riding on the main power frequency. This generates an audio hum even from tube lights, fans and such domestic equipment. I was wondering if this applies to your case also.
  
  Bioramani
• 

  lovejeet

  is your speaker system too near to the ups????
• 

  narayana murthy

  lol guys by my knowledge that beep sound don't come from speakers of system it comes ups itself if any one interested they can test by switching off the speakers
• 

  Ramani Aswath

  lovejeet

  is your speaker system too near to the ups????

  I am talking about line conducted harmonics. In the case of tube lights it is the choke that hums.
  
  Bioramani
• 

  narayana murthy

  bioramani

  I am talking about line conducted harmonics. In the case of tube lights it is the choke that hums.
  
  Bioramani

  yes i too listened the sound because still my tube light is creating that irritating sound but as per my knowledge sound won't come from speakers because i tested it once i switched off the speakers but still i am able to listen sound
• 

  Ramani Aswath

  narayana murthy

  yes i too listened the sound because still my tube light is creating that irritating sound but as per my knowledge sound won't come from speakers because i tested it once i switched off the speakers but still i am able to listen sound

  NM Garu, If the speaker housing has the power supply of the amplifier it is possible that the transformer in that is making the noise.
  
  Bioramani
• 

  ABCD ABCD

  One thing, i'm sure that the sound is from the speaker. I don't hear that from UPS(Inverter). How can Speaker's sound depend on sine wave?
  So, my ques is: 'Why wont that happen to normal frequency of 50/60Hz?,(if it can happen to other frequencies)'
  
  I can even see some lines moving from up to down in my PC's monitor. As it happens when you capture it using a video camera.
• 

  Ramani Aswath

  mreccentric

  One thing, i'm sure that the sound is from the speaker. I don't hear that from UPS(Inverter). How can Speaker's sound depend on sine wave?
  So, my ques is: 'Why wont that happen to normal frequency of 50/60Hz?,(if it can happen to other frequencies)' I can even see some lines moving from up to down in my PC's monitor. As it happens when you capture it using a video camera.

  In our company we were recently setting up a video conferencing facility. We found that the SMPS in some models was leading to a hum in the audio and a waving display, while others did not. It is the Electro Magnetic Interference, which can be radiating or line conducted, which sets up this disturbance. When talking on a landline any near by cell phone getting an incoming call sets up a disturbance, even though there is no connection.
  
  Bioramani