FW500 Ground/Bond Issue

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My RE system: 2 x FX 3048MT, Flexmax 60, Flex 500 AC/DC cabinets & mount, PSX-240 Autotransformer, Hub, Mate, 6 x Kyocera 210W panels, Air 403-48, 20pc Sterling 140 Ah AGM batteries, 48V off-grid system.

FW500 Ground/Bond Issue

Post by JCO »

I have just been testing the 48V AirX turbine wired into my FW500 box and found that it was energizing the entire box (bad buzz!). It is wired through the appropriate switch and breaker on the positive side, and wired directly to the negative buss. After removing the supplied bonding wire between the negative buss and the ground buss, there is still residual voltage, albeit at a very low rate. Two questions for the furoum:
1) Is this common for the FW500?
2) Why is the DC box shipped with the bonding wire between the negative and ground busses?

Kent Osterberg
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Re: FW500 Ground/Bond Issue

Post by Kent Osterberg »

1) No, this isn't normal. You should not get a buzz when touching the Flexware 500 panel.
2) A negative to ground connection is generally required to provide a low resistance path to ground so that ground faults will trip the dc breakers.

From your description, it sounds like there may be dc current flowing through the ground electrode(s). What kind of ground electrode is the Flexware 500 connected to? Is there a ground electrode at the wind generator? Do you have a ground wire running from the Flexware 500 to the wind generator?

Is there any chance that the buzz disappears when you turn the inverters off? If so, there may be a grounding problem on the ac side of the system.
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Re: FW500 Ground/Bond Issue

Post by tallgirl »

This almost sounds like the wiring from the AirX is reversed. Any chance that's the case?
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