apc BX1600MI-MX buz or sssss sound

[sena]

Hello, I want to ask, I just bought an APC BX1600MI-MX UPS, and when I turn it on, there is a sound (buzzing or sssss cesss). Is that normal? The sound appears when the UPS is plugged into the electricity. The sound is there when the UPS is off or on. When it is off, the sound gets smaller. When it is on, the sound gets louder, but the sound is not too loud.

[Teken · Accepted solution]

All electronics produce some level of noise even if you can’t perceive it.

Your specific APC UPS is rated to produce 40 dBA of noise at 1-3 meters which is normal.

You can google what the equivalent noise is which typically means a quiet room. Depending upon the specific model UPS the system may incorporate a fan as such this is one source of noise.

In other cases the noise is generated by the charging circuit. Other times the noise is produced by the inverter circuit especially when the system transfers to battery only mode. All the above are normal but may not be acceptable to a person if they are very sensitive to ambient noise.

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[sena]

My UPS fan doesn't turn on even though it's on. Is that really the case? or only when the UPS is at a certain temperature.

[Teken]

The internal fan is controlled and managed by the firmware in place. Generally speaking if the fan is not on normally than it will activate when the following conditions exist:

On battery, charging, high output exceeding 50% load, high ambient temperature, internal battery compartment threshold has reached etc.

NOTE: Systems that have a fan running all the time are dual stage fans. Thus will engage the second stage (maximum) speed if required.

APC does not use or employ PWM (variable) fans in any UPS model to date. 🤦‍♂️

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[sena]

Thank you very much for the information, btw at the beginning I wrote a little wrong  my ups BX1600MI-MS NOT BX1600MI-MX ( MS) not ( mx)