offered by Busse-Yachtshop.com
AIR 403 Land Manual Document #0049 REV D
SOUTHWEST WINDPOWER 8/20/2001 41
drops off to about 150 watts. The wiring could be sized for the maximum current
output of the turbine, but this output is seen primarily in gusty conditions.
We have recommended wire sizes that are intentionally small to save the customer
from spending a lot of money on wiring, while still experiencing no more than a 5%
annual energy loss due to resistive line losses. In most cases this will be acceptable
for local electric codes – please contact your installer or local electrician to be certain
of your area’s specific requirement.
#24 What is the difference between copper and aluminum wire?
Aluminum wire is less conductive; so generally it must be bigger for the same amp
load and resistive losses as copper.
#25 What is the difference between welding cable and standard stranded cable?
Welding cable is typically very finely stranded to be very flexible, where as standard
cable will typically hold its shape. Always be sure that the environmental rating of the
insulation of your power cable matches the application.
#26 Why does my AIR regulate before my batteries are fully charged?
This will happen if your wires are too small, as discussed in the voltage drop section
above. This can also happen if the AIR is connected in parallel with another charging
source, and there is some distance between this connection and the batteries. The
other charging source can create a voltage drop because of its own current output,
which will raise the voltage that the turbine “sees”.
Be sure to check ALL of your wire connections. All connections should be soldered,
split bolted, or secured in a terminal block. CRIMP-ON TYPE CONNECTORS MUST
NEVER BE USED! These are poor connectors for high currents and will almost
always have some resistance at the male/female connection that will increase your
voltage drop and line loss.
#27 How does wire sizing or voltage drop affect the regulation of my AIR?
When current (amps) passes across a resistance (ohms), it creates a voltage
difference (voltage drop). Higher current or higher resistance causes a greater
voltage drop. All wire has some resistance to it; the smaller the wire the greater the
resistance. If you use undersized wire, then the turbine will see a higher voltage than
the batteries as it’s output increases, even though the battery voltage may remain the
same. If the voltage at the machine exceeds the regulation set point of the control
circuit, then the turbine will regulate even though the batteries are not fully charged.
Example: A 12V AIR is connected to a very large battery bank via 75 feet of 10g
stranded wire. The battery bank is at 12.0V.
The resistance of the wire is 75 ft x 0.00129 ohms/ft = 0.097 ohms, multiplied by 2
conductors for the positive and negative = 0.194 ohms. When the turbine is
producing 1 amp, the voltage drop across the wires is 1 x 0.194 = 0.194 volts, which
isn’t that much. But at 15 amps, the voltage drop becomes 15 x 0.194 = 2.91 volts.
This means that while the battery bank is at 12.0V, the turbine thinks it is at 14.91V.
If your turbine is set for 14.1V (the factory setting), the Autobrake will engage. There
will then be no voltage drop, the turbine will see 12.0V, and will begin charging again
until the output climbs again. The turbine thus cycles in and out of regulation, even
though the battery is not fully charged.
