SU700NET HAS LOUD WHINING SOUND

[BillP]

This question was originally posted by red on APC forums on 3/4/2008

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I HAVE A SU700NET AND IT HAS A LOUD, HIGH PITCHED WHINING SOUND COMING FROM IT. THERE IS ALSO A LIGHT ON THAT SAYS TOO MUCH LOAD CONNECTED. WE HAVE HAD THIS FOR YEARS AND NOTHING HAS CHANGED AS FAR AS WHAT IS CONNECTED TO IT. ANY SUGGESTIONS?

[EZ_Button_apc]

This was originally posted on APC forums on 3/4/2008

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Regardless, I'd still try reducing some load on the unit to see if there is any effect. How man load LED's are on the left side? If the overload LED stays on, you're probably going to want to just power cycle the unit, which would mean shutting off your load temporarily.

[KVAr_apc · Accepted solution]

This was originally posted on APC forums on 3/5/2008

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Do you have the 940-0024C or equivalent interface cable?

Connect to the UPS with HyperTerminal at 2400bps, xon/xoff, everything else default.

send shift y, wait for response "SM"
send shift p, then you'll get the relative load in percent. You really should upsize your UPS if you get more than 75%.

Even if the connected items are the same, loads do change, so if you were just a hair below the trigger point, you might set it off.