E2S BExS110D-SIL Instruction manual - page 12
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Document No. D197-00-601-IS Issue F 16-06-17 Sheet 12 of 19 (12)
Multiple Unit Configuration
When multiple units are used in the system, the following considerations are to be made by the customer:
1. Customer panel capabilities -
The customer is required to identify the minimum change in current the panel can detect (Panel resolution). This will
therefore determine what resistors values to pick in section 3 below.
2. Topology -
The customer has a number of options on how to set up the system.
▪
A single unit topology is where only one unit is connected to the customer interface line, as shown in figure
10.
▪
A series topology is when each unit is connected to one another as shown in figure 16.
▪
A star topology is when each unit is connected to a central source as shown in figure 17.
3. Resistor -
The customer is required to calculate the total resistance a system, to determine the change in current when a fault
occurs. As mentioned above, the customer can select a system EOL resistor. The default fault resistor value i
s 2.2kΩ
which is recommended and is fitted according to the configuration topology chosen.
Panel
Resolution
Topology
Resistor:
Power Supply
FR & EOL
No. of
Units
Steady Mode
Active/
Monitoring
Fault Mode
1 unit fault
2 units fault
All units fault
5.5mA
Series
FR =
2.2kΩ
&
EOL =
2.2kΩ
3
EOL Only
EOL + FR
EOL + (2 x FR)
EOL + (3 x FR)
5.5mA
Star
FR =
2.2kΩ
&
EOL =
2.2kΩ
3
3 x EOL
(3 x EOL) + (1 x FR)
(3 x EOL) + (2 x FR)
(3 x EOL) + (3 x FR)
5.5mA
Series
FR =
2.2kΩ
&
EOL = 3.3
kΩ
3
EOL Only
EOL + FR
EOL + (2 x FR)
EOL + (3 x FR)
5.5mA
Star
FR =
2.2kΩ
&
EOL = 3.3
kΩ
3
3 x EOL
(3 x EOL) + (1 x FR)
(3 x EOL) + (2 x FR)
(3 x EOL) + (3 x FR)
Table 3
Note: - Cable fault
• Between the panel and the first unit, a cable short, increases the current (presenting a short circuit to the panel), and a
cable cut/open reduces current (presenting an open circuit to the panel).
• In series topology a cable short between units will short out one of the current sense resistors which results in an increase
in the current used by the unit, and a cable cut/open reduces current (presenting an open circuit to the panel).
• In star topology a cable short between units will short circuit the SIL 2 monitoring line hence presenting a short circuit to the
panel, an open circuit fault on one of the units will effectively remove one of the current sense resistors reducing total
effective resistance hence decreasing the total current seen by the panel.