"Ron" wrote in message
. net...
Just about every gen manufacturer has an automatic transfer switch that
could be used to do what you want.
For example http://www.generac.com/industrial/pr...o_transfer.asp
If it will be the first item after the meter (and before the main
disconnect), the ATS must be service rated.
"reality intrudes" wrote in message
...
hello all,
we will soon have a modular delivered to our rural area and want to have
a
liquid-cooled, propane, automatically kicks on, one-phase, standby
electric
generator sufficient (prob ~30kw) to power the whole house without
restriction (200amp service- incl well pump; electric range; frige &
freezer; TVs; computers; geothermal heating/cooling/water heater
equipment;
etc).
all the electricians the construction supervisor has contacted have all
quoted $5,000+ labor to hook up our supplied materials- supposedly to
wire
the individual circuits to be powered.
isn't there a way to have an automatic switch in line after the meter
and
before the house's panel- thereby bypassing the labor to install
individual
circuits? if so- what brand of switch, would i need to get an even
bigger
generator to avoid any overloading...
thanks in advance,
kurt

Kurt:
That is exactly how our Onan diesel/electric generators worked in a number
of our small telephone exchanges some 30-40 years ago.
I can't recall the size of our generators but IIRC they were less than 30
kVA (Kilovolt amps) which is approximately the same thing as kilowatts,
depending on the phase angle load factor. Phase angle depends on the type of
electrical load; would you have many electrical motors in fridges, freezers,
air conditioning units, milking machines, air compressors, swimming pool
pumps, maybe a motorized stair lift for seniors etc. etc. that you would
wish to power during a commercial power outage? If so these would determine
the size of generator unit you require.
In our installations, normally the commercial power went straight through
the automatic Onan transfer switch to power the whole building. When a
commercial power failure occurred the transfer switch released; very heavy
relay contacts changed over the building load to the out put of the
generator. Another set of contacts within the transfer switch started the
generator which was standing ready with an automatically and fully charged
starting battery in a special room fitted with IN and OUT ventilation. I
can't recall exactly but in winter if the room temperature dropped I think
there was an electric heater in the sump of the generator engine to ensure
engine starting? There may have been a slight delay to of say 10 or 20
seconds? allow the engine-generator to get up to speed.
Various other things happened, such as the moment the generator started it
opened the ventilation louvres in its engine room. If the louvres did not
open the engine room might overheat and or the motor might starve for lack
of air! So there was another circuit for that which would shut down the
generator unit!.
Also I recall that there was either a time delay circuit or one had to
manually shut down the generator once it had fully and properly started and
taken up the electrical load of the building. This was so that if the power
came back on again quickly or the commercial power was 'swinging' off then
on again, due, say, to a broken and hanging transmission line wire it would
not damage the installation. Some commercial power company line reclosers
will try at least three time to restore power and that could result in three
'hits' of partial voltages before the commercial power finally switched off!
Once installed I recall that we did not have too many problems and the
generators did not have much running time.
I do recall that the worst problem was when the AC mains supply voltage did
not fail .i.e. go off completely, but only dimmed to say half voltage or
something, The transfer switch needed almost full line voltage to operate
but, like most electromagnetic relay devices, would not release until the
voltage dropped to around 40%. Hence we could have devices in the building
dropping out, not operating correctly and the lights either dim, or if
fluorescent, they went out and the generator did not start! The solution was
for a technician to dash downstairs to the generator room; manually start
the diesel whereupon it would stay operating until it was understood the
power commercial power outage was over.
AFIK transfer switches are not unusual item. Today there may be available
ones more sensitive or adjustable to the commercial voltage; that could be
good, or might mean that the generator would run at every little twitch or
variance of supply; especially on a long rural line!
A 30 kVA generator is no small unit and is a considerable investment. It
will also generate quite a bit of 'waste' heat when running. You could add
to complexity by making use of the wasted heat from the radiator fluid of
the engine? Also the hot air from the genertaor room or enclosure? In a cold
climate both 'waste heat' sources could be could be useful.
I would respectfully suggest that proper design and consideration of all
factors will ensure proper operation and avoid damage to the unit and the
building systems. The other aspect, which could be most embarrassing, was
when we installed one such unit in a crucial location and it failed to start
during an ice storm! We were about to mount an INVESTIGATION when it was
found; I can't remember exactly but it was something simple such as someone
flipping a switch not realising it was 'Disable Automatic Start' or had the
fuel stop turned off after reconnecting a fuel line, or something equally
ridiculous. Some of our installations were three phase but the principle of
operation was the same as single phase, with a slight added complication
that I made a modification for, but won't go into here.
If a manual transfer switch were to be used many of the considerations are
exactly the same; manually one would observe loss of commercial power,
manually start the generator, when up it is to speed manually operate the
transfer switch to transfer the house load to the generator and then
manually monitor the operation for a while to ensure nothing is amiss, no
overheating, lack of ventilation etc. You don' want to use up all the air
and asphyxiate people for example because a louvre/shutter hasn't opened!
Momentarily after power failure many of the house load items will have
stopped due the loss of commercial power and will restart as the generator
provides the power this means that the just started and still cold generator
has to be large enough to handle these starting loads, not just sized to
carry the load when everything is running normally. For example a fridge
will stop and then restart as the generator picks up the house load.
I have no idea now what a transfer panel costs; but if the $5000 is to
design, obtain and install the additional materials including the transfer
panel/switch to ensure operation as above that might be quite reasonable?
One could infer from your post that you only have the uninstalled generator
itself and maybe the propane tanks etc.?
There is a considerable difference between having a generator sitting in a
shed or barn on the property that you plug things into on an ad hoc basis if
and when needed and a generator properly integrated into a building's
electrical system in a safe an insurable manner. You may need for example
Carbon Monoxide, Propane gas, engine overheat and other detectors linked to
alarms within the house to meet insurance requirements?
Hope this helps. Terry.