Elgar SmartWave SW5250A Operation Manual page 43

SW 5250A•SW 3500A•SW 1750A
The following notes apply to Table 2–9 and to the power cable definition:
1. The above figures are based upon insulated copper conductors at 25°C (77°F),
two current carrying conductors in the cable plus a safety (chassis) ground.
Columns 3 and 4 refer to "one way" ohms and IR drop of current carrying
conductors (e.g., a 50-foot cable contains 100 feet of current carrying conductor).
2. Determine which wire gauge for the application by knowing the expected peak
load current (I
and the one way cable length.
The formula below determines which ohms/100 feet entry is required from
Column 3. Read the corresponding wire gauge from Column 1.
(Column 3 value) =
V /[I x 0.02 x (cable length)]
loss peak
Where:
Column 3 value =
Entry of the table above.
Cable length =
One way cable length in feet.
V =
loss
Maximum loss, in volts, permitted within cable.
Special case: Should the V
maximum amperes (Column 2). In this case, the correct wire gauge is selected
directly from the first two columns of the table.
Example: A 20 ampere (I
drop (V ) along its 15-foot cable (one way cable length) requires (by formula)
loss
a Column 3 resistance value of 0.083. This corresponds to wire gauge size 8
AWG.
If the cable length was 10 feet, the Column 3 value would be 0.125 and the
corresponding wire gauge would be 10 AWG.
Operation Manual
), the maximum tolerated voltage loss (V
peak
requirement be very loose, I
loss
) circuit which may have a maximum 0.5 volt
peak
Installation
) within the cable,
loss
may exceed the
peak
2-17