APC BX1100C-IN Fan producing annoying sound

[Anonymous user]

I have recently bought a APC BX1100C-IN for my PC so that I can save my work properly during power cut. After 2-3 days of usage I have noticed that its fan starts to run at full speed during night and creates very annoying sound. Although fan runs all the time but it's not noisy but when when it run at full speed it produces lot of noise. It's so loud that I have to move it in another room, I am performing this ritual from past 1 week continuously. I don't know if it's normal or what. Can anybody tell me if it's normal or it has some problem.

[BillP]

Hi Atinesh,

Many power companies will reduce their power output during the over-night hours to conserve energy. I think what your finding is that the utility voltage is dropping to the point in which the AVR (Automatic Voltage Regulation) of the UPS is being engaged. During the period in which AVR is enabled to maintain adequate output power to your load, the AVR transformer will increase internal temperatures as a result. The UPS will then cycle up it's internal fan to remove this excess heat, to try an maintain an nominal temperature throughout the unit. So I would say this is a normal response to the utility.

Secret Squirrel

[Anonymous user · Accepted solution]

KoOn 1/2/2019 8:07 PM, Secret said:

Hi Atinesh,

Many power companies will reduce their power output during the over-night hours to conserve energy. I think what your finding is that the utility voltage is dropping to the point in which the AVR (Automatic Voltage Regulation) of the UPS is being engaged. During the period in which AVR is enabled to maintain adequate output power to your load, the AVR transformer will increase internal temperatures as a result. The UPS will then cycle up it's internal fan to remove this excess heat, to try an maintain an nominal temperature throughout the unit. So I would say this is a normal response to the utility.

Secret Squirrel

I have contacted APC, they sent a service boy who told me to disconnect UPS from AC mains when not in use, on the contrary on the ups it was written always let it connected to the AC mains. Now when I turn off the computer, I turn off the UPS and switch off the main AC supply to UPS, fan runs at full speed for 4-5 mins then stops. Now it's working fine.