TRAFFIC CONTROL TELEPHONE SYSTEMS Circuit - Sam Hallas

Line Voltage Curves
Fig. 14.
The operating battery voltage required depends on the line resistance and the
number of selectors bridged across the line. Figure 14 shows the voltage required for
10-80 selectors bridged across a line from 400 to 6,000 ohms loop resistance, calculated
on the assumption that the selectors are equally spaced. These curves may be
used for all normal arrangements of way stations and only fail when a large number of
selectors are connected to a long line at one point.
Figure 15 gives the corresponding curves for 10-60 selectors operated over a
line of 400 to 3,000 ohms through a 341-A or AAJ 4100-1 Transformer.
Figure 16 gives line voltage corresponding to Figure 15, but for operation through
two 70-A or Q 4104-1 Repeating Coils connected in series-aiding.
The voltage figures allow for average line conditions, irregularities in the distribution
of Way Stations, etc., and have been decided upon after a number of tests
under practical working conditions. We therefore strongly recommend that these
figures be used where at all possible, and although perfectly good results are often
obtained with considerably higher or lower voltages, we do not recommend a variation
of more than 10 per cent. above or below these figures without preliminary
working tests.
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