F04 Clamp Short

[Anonymous]

This was originally posted on APC forums on 11/13/2010

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What does F04 Clamp Short mean and what would cause it?

[rau_apc · Accepted solution]

This was originally posted on APC forums on 11/14/2010

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I don't know what component inside the UPS is deffective, but what this code is saying is that samething is short circuited inside the UPS, it could be anything, but the word "clamp" reminds me of a varistor ou MOV, which is the component that clamps short when there is a voltage surge condition and comes back to its normal state, an open circuit, when the voltage surge is gone. Sometimes it clamps short for good when it is hit by a large surge or just by absorving and shunting to ground many small surges. If your UPS is running fine perhaps one varistor between neutral/ground is short circuited which won't interfere in the UPS itself, but it is a safety hazzard for the user, because it increases the risk of electrocution.

I can't tell you for sure that this is the right explanation for this error code, but I think it is something close to it.

[Anonymous · Accepted solution]

This was originally posted on APC forums on 11/13/2010

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What does F04 Clamp Short mean and what would cause it?

[FBMBoomer_apc · Accepted solution]

This was originally posted on APC forums on 5/3/2015

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I found a method to clear this error and make the UPS work again. I disconnected the UPS. I then disconnected the batteries for 5 minutes. I powered it up on my work bench and it looked OK. I then uninstalled the powerchute software to make sure it would not remember that my UPS had an error code. I reinstalled the latest power chute software and all has been well.