User guide

8
TAI16AEA
October
200
5
–
Issue 6
Triguard SC300E
THEORY OF OPERATION
The analogue input termination card provides a convenient and safe means of connect ing up to
16 field input channels to an analogue input module in the SC300E chassis. As shown in
Figure 2 - 3 each channel (a pair of lines) is connected via a 63mA fuse to the analogue input
module,
which may be configured for either voltage or current monitoring inputs. Power for the
field
loop circuits is supplied from an independent external source.
Transient suppression
Each termination card circuit also embodies two methods of transient suppression.
A transient suppressor diode is fitted across each input to the analogue input module in the
SC300E chassis. The diode provides a discharge path for transient energy pulses that may
appear on the analogue input line following lightning strikes etc.