Thursday, Feb 15, 2007 at 09:03
Hi Mike
The main purpose of my response to this
forum is to address the original question about the use and earthing of an inverter.
The main issue is HANDLE WITH CARE because 240 volts AC is potentially very dangerous no matter from where it is sourced.
It takes a very low number of milliamps to cause a serious accident.
If in any doubt at all get professional advice. Good luck for anyone who is unfortunate enough to be in a position of trying to justify their actions that did not comply with the Australian Electrical Standards.
As far as your questions;
1. A possible dangerous situation could be a faulty inverter e.g. the active shorting to the metal case, and an appliance with loose or broken earth and neutral wires and poor insulation resistance to the metal case (e.g. as often found in old drills and Mix Masters). There are many different scenarios.
2. Earthing the inverter to a earth stake may prevent some potentially dangerous situations but cannot make the use of an inverter 100% safe in every situation. Like a
home installation, it is obvious that the MEN system does not eliminate every potential electrical accident; however, it assists in limiting some dangerous situations.
I guess that there are some situations where the MEN System may potentially create a dangerous situation.
3. I have assumed that the earth pin and neutral in a common inverter are linked and connecting it to an earth stake makes it a simple MEN system. The advantages of MEN systems have been debated and are proven since beginning of time, electrically speaking of course.
I once did maintenance work in a Power Station where some GPOs were not earthed in special situations to isolate them from the system. It all can get very complex.
Cheers
Phil
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