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Triguard SC300E TDO16AIN 16-Channel D/O Termination Card 24Vdc
THEORY OF OPERATION
Figure 2-4 shows a circuit diagram of a typical digital output channel.
Power supplies for the termination cards are normally provided by a Power Distribution Panel
PDD24.
Power for the digital output channels is distributed as shown in Figure 2-3 . Soldered links LK1
to LK4 are normally present, and in low load applications, external power can be connected to
any one of the four inputs FS1 to FS4. For high load applications, or where the channel groups
require different supply voltages, cut the links and supply FS1 to FS4 individually.
Each digital output channel is powered from a common +ve bus. An indicating fuse is fitted in
the digital output signal line to the field device. The 'fuse failed' output from each fuse is
connected to a common alarm bus. If any fuse fails, local indication is provided by the
illumination of the Fuse blown LED LD1. A signal to operate a remote alarm is available at
Alarm output PL1.
The -ve bus may be grounded via TS1 if required, preventing the power supplies from 'floating'
when the chassis cable is disconnected.
TDO16AIN October 2005 – Issue 6
7
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