Originally Posted by
travelite
Jack,
The way I understand it, all loads are wired through the inverters, even though the summation of the loads exceeds the inverters 4000W ability. When on shore or genny power, the inverter passes the shore/genny power along to the loads. If the voltage starts tapering off, then the inverter can step in to supply more power to the grid (shore or genny). When switching off the shore or genny power and migrating to inverter power, some of the loads have to be pruned or else the inverter will be overloaded and the circuit breakers will pop; i.e., some sort of automatic or manual power management must take place. I'd like to hear more from Vantare and Parliament owners on how they handle this transition. If this isn't correct, please Vantare owners, correct me.
Vantare never really did put a true automatic unloading system in their coaches, but instead put a warning disclaimer on the galley Main Distribution Panel (MDP) to mention that the customer needs to make sure the load amps on each leg must be under 35amps before disconnecting shore power or stopping the generator to prevent inverter overload. Even in their latest generation of coaches with the motorized Square D circuit breaker system, what they did and called an unloader was not fast enough to prevent inverter overload.
For Parliament Coach owners, however, I utilized a micro PLC and designed the logic the major 120 and 240 Volt loads in the coach. The PLC senses both the status of the generator and shore power, and a change in either one would cause the PLC to unload automatically all the heavy loads, then depending on what happened next, stage back on loads that would not overload the inverters. This feature was automatic, so the customer did not have to worry about what was on and running before starting the generator or unplugging his coach.
Next month I have my first project of putting a similar unloading system into a 2001 Angola which has the 4000 watt Trace inverters. I will write an article on this retrofit after I have completed it, and hopefully have the Angola owner write some note about it from his standpoint.
Ben Cummings
U.S.A. Luxury Coaches, LLC
Clearwater, FL