Site wiring fault when on generator SU2200RM2U

[Anonymous user]

I have a rack mounted 2U SmartUPS 2200 protecting 6 servers, a tape drive and various network infrastructure pieces.

I also have a Generac Guardian generator for premises backup power.  this unit was installed and certified by an electrician.

Between the 2200 and the devices i have an APC 7900 PDU, for two reasons - 1) i have more than 6 devices i need that need protecting and 2) i can use the PDU's to remotely power cycle the servers if regular reboot comamnds don't work.

When i'm running on "city" A/C power, the UPS runs just fine.

When the power goes out, the UPS keeps everything running, but once the generator kicks in i hear a loud clicking sound every few seconds, the Site Wiring Fault Indicator light is blinking and then all the devices plugged into the UPS shut off.

It's almost behaving like ti's trying to reboot every 5 seconds, which is a problem because the PDU's take about 30 seconds to initialize and as such the never restart to the point where they can provide power to what's plugged into it.

I checked the APC site and the Site Wiring Fault indicator is typically caused by

     1) Missing Ground Wire

     2) Reversed Polarity

     3) Overloaded Neutral

I used a circuit tester that detects basic wiring problems, both on "city" power and generator and 1 and 2 were just fine.

I looked inside the transfer case and it looks like even though the generator panel supports 16 circuits, it uses a common neutral.

So i'm guessing that the Overloaded Neutral could be the issue - but bear in mind i'm a computer engineer, not an electrical engineer, so i'm really just guessing.

Given that this is how the generator system is designed, i'm presuming that it can't be changed, so my questions are.

* does anyone have experience with running SmartUPS's and generators?

* is there another explanation to why the Site Fault Wiring Indicator is coming on?

* is there a way to adjust the sensitivity of what triggers the SFWI?

* is there a way to turn off the SFWI feature?

* are there any other options?  (that don't involve making changes to the generator or generator transfer panel)

Thanks in advance

B

[Anonymous user]

I am looking for a response for this.  I have the same problem with the current SMT2200.

[BillP · Accepted solution]

Hi,

The reasons a Smart-UPS would trigger site wiring fault are listed in the original post. 1 difference with the SMT is you can disable site wiring fault via the LCD panel. Go to Configuration and verify the UPS is set to Advance. Then continue on in the Configuration menu and you will see Site Wiring fault. There you can disable it.

Below is from the attached User's Guide page 18. 

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