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2-5SectionBackup Power Supply
10
When
total transmission loss from the system is subtracted from the transmit/re
-
ceive
dif
ferential of the Link Adapters, the margin must be at least 4 dB. T
o deter
-
mine
total transmission loss, first calculate the loss over the
cable by multiplying
the
loss/km by
the total length of the cable. Then calculate the loss at the con
-
nections
by multiplying the loss/connection by
the number of connections. Final
-
ly,
add the cable loss and the connector loss. Subtract this figure, the total trans
-
mission loss, from the transmit/receive differential. If the difference is greater
than 4 dB, then the cable length is acceptable.
Distance: 2.5 km; Connecting points: 4; Connecting method: permanent
When
this total transmission loss of 7.9 dB is subtracted from the 13 dB transmit/
receive
dif
ferential of the Link Adapters, it leaves a margin of 5.1 dB. The 13
dB
includes all loss at the Link Adapter connectors.
Distance: 2 km; Connecting points: 3; Connecting method: connectors
When
this total transmission loss of 8.1 dB is subtracted from the 13 dB transmit/
receive differential of the Link Adapters, it leaves a margin of 4.9 dB, safely
above the minimum margin of 4 dB.
2-5 Backup Power Supply
Link
Adapters which depend on a power
supply (i.e., all except the AL001) are
unable to transmit signals when power is cut off. Link Adapters AL002-(P)E,
AL005-(P)E, and AL006-(P)E, however, have auxiliary power input terminals
which
can be connected to a battery to ensure continued operation even when
the AC power supply is cut off.
Only
the three Link Adapters listed above have this terminal.
They can operate
on a low voltage (12-24 VAC/DC) power supply in place of their normal power
supply of 100/200 VAC. When it is necessary to have a backup power supply,
connect
a 12V battery to this terminal. If the battery is left unused for a long peri
-
od
it will discharge. It must either be periodically charged or connected to a float
-
ing
charging device. T
o avoid overcharging, set the output voltage at 13V
. Do not
use a 24V battery.
Example 1
Example 2
Using the Auxiliary
Power Input Terminal