Renewable Energy Questions/Discussion > Wiring and Code discussion

A small SAPS - DC Earthing/Bonding/Fault Protection

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Pete:
Can you give an example of something on the DC side that can cause input overloads? Other then PV gone-wrong I cant think of anything else... I wont be charging with a generator either.

Why bond AC Earth/Neutral at the PJ Mainboard - as opposed to using a MEN link in the AC Dist Panel?
I assume to bond at the Mainboard is simply a matter of a short length of wire with ring terminals linking the AC -/Earth screw down terminals? My intent was to use an RCBO with MEN in the AC Dist Panel.

First question. There is always the possibility that the charge controller will fry itself, That would lead to it draining the batteries.
As you suggest a shorted PV panel , or even a wiring fault caused by dry joints or small toothed animals eating wires.

Second question is that the powerjack may be used other than for powering a house with a proper MEN connection on the main switchboard. In a true stand alone use it would then not have an MEN and no RCD ( safety switch ) would work.
I always use MEN systems myself. At least then safety switches work. Apart from the requirements of Australian Standard 3000 that require MEN connections.
Glad you have simplified the setup, Simple is always best.
I use DC breakers between my panels and regulators and Automotive type 50 amp gold fuses between the regulators and batteries. The Auto fuses are much cheaper.
OZ says that he has talked to manufacturers and that AC breakers are fine for up to 60 volts DC.
Cheers
Pete

oztules:
Actually Clockman (France) talked to the manufacturers, and you derate the current  rating by 10%. in the 60v range..... I won't build an inverter without them now... never DC, always AC breakers on the battery line.

This saves the boards, but causes some start up problems sometimes, but it is worth it, as you only start up once.

Inrush currents are in the region of 400-600 amps and more for the 6 cap versions..... you really need to bypass the switch/o/loads for this "splat", or slow start it with a resistor or globe in series until at least you get to say 40v or more, then the spark is quite minor in magnitude. On 8010 based inverters, they will require a push of the reset to get the brains functional after soft voltage input.

I never run a MEN scheme unless there is a house or shed or multi appliance load with it's "neutral" earthed at the switchboard.... otherwise it is pointless, and possibly dangerous if you are likely to hook up to a MEN system sometime in the future... you may have phase problems with which side of the tranny you earthed in the inverter, and which side is earthed to neutral at the switch board.,... beware....

I only allow the "earth" in the inverter to be floating until the MEN system your going to attach to tells it what to do.


..............oztules

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