Re: Grounded Conductor Problems
It strikes me that there are two components of the topic of this thread: </font>
- <font size="2" face="Verdana, Helvetica, sans-serif">The indication of an open service entrance neutral.</font>
- <font size="2" face="Verdana, Helvetica, sans-serif">Using a device (intelligent electronics) to trigger a circuit interrupter.</font>
<font size="2" face="Verdana, Helvetica, sans-serif">I look at the neutral as being real helpful to minimize part of the EMF associated with connecting an occupancy to a multi-ground PoCo distribution grid.
As the neutral impedance increases, the more unbalance current will flow from the main bonding jumper into the grounding electrode system, which is physically away from the service entrance conductors, so the EMF intensity increases in the occupancy.
What if the ONCI were an active device that had an electronic "choke", something like a triac, that was in the current path away from the neutral, that could choke steady current going into the GES, yet allowed short rise time currents (say rise times of 10 seconds or less) to pass.
The "high band pass" would allow short circuit events involving the GES to clear overcurrent protection. . .but the steady state 60 Hz current could be choked off, congregating most, if not all, of the unbalance current in the service entrance conductors, getting them to a timewise mostly near zero EMF.
The impedance controlling triac, between the MBJ and the GES, would have to failsafe to continuity. The simple wall dimmer triac does this most of the time when a fixture short occurs. Mimic that dimmer failure behaviour in the impedance controlling triac and also build in the programming for the trigger for a circuit interrupter that will operate when the neutral impedance spikes, and one will have
an EMF moderating open neutral circuit interrupter
