E2S GNExB2X05-S Series, Instruction Manual, Page: 12 / 20

European Safety Systems Ltd. Impress House, Mansell Road, Acton, London W3 7QH www.e2s.com Tel: +44 (0)208 743 8880
Document No. D156-00-621-IS Issue 1 27-10-22 Sheet 12 of 15
Figure 14: Schematic of SIL 2 system wiring for fault detection in standby mode only
–
2 wire installation.
To evaluate the total current drawn from the SIL 2 unit, use the equation below.
In standby mode, where there is no fault, RLY 1-1 is open. This means the voltage only passes through the customer EOL resistor
and the current drawn from the SIL 2 board is 25mA. Therefore, the equation for a No Fault scenario is then:
In standby mode, where there is a fault, the circuit is closed. This means the voltage passes through both the customer EOL resistor
and current sense resistor and the current drawn from the SIL 2 board is 20mA. The customer must first calculate the resistance of
the two resistors in parallel before applying the currents to the equation. The equation for a Fault scenario is then:
Table 5: Resistor combinations and the currents drawn when no faults and faults occur.
If multiple SIL 2 alarm horn sounders are to be cabled in series, the monitoring connections differ from that of a single beacon. For
more information see manual D197-00-621-IS available from the E2S website.
I
(Total Current
drawn)
= (Current drawn from
Fault Resistor)
+ (Current drawn from
Customer EOL resistor)
+ (Current drawn
from SIL board)
(Standby Mode, Total Current drawn - No Fault)
=
(0mA)
+
(See table 5)
+
(25mA)
(Standby Mode, Total Current drawn - Fault)
=
(Total Resistance when EOL & FR in parallel)
+
(20mA)
Standby
Mode
Power Supply Fault Resistor Customer EOL Resistor (Fault Mode Only)
Current
drawn
from SIL
Board
Total
current
drawn
Resistor
Value
Current
drawn ( )
Resistor
Value
Current
drawn ( )
Total
resistance
Current
drawn ( )
No Fault
2.2 kΩ
0 mA
2.2 kΩ
10.9 mA - - 25 mA 35.9 mA
Fault
- -
1.1 kΩ
21.8 mA 20 mA 41.8 mA
No Fault
1.
0 kΩ
0 mA
1.0 kΩ
24.0 mA - - 25 mA 49.0 mA
Fault - -
500 Ω
48.0 mA 20 mA 68.0 mA
No Fault
2.2 kΩ
0 mA
3.3 kΩ
7.3 mA - - 25 mA 32.3 mA
Fault - -
1.3 kΩ
18.2 mA 20 mA 38.2 mA
No Fault
1.8 kΩ
0 mA
3.9 kΩ
6.2 mA 25 mA 31.2 mA
Fault - -
1.2 kΩ
19.5 mA 20 mA 39.5 mA
No Fault
1.8
kΩ
0 mA
4.7 kΩ
5.1 mA - - 25 mA 30.1 mA
Fault - -
1.3 kΩ
18.4 mA 20 mA 38.4 mA
No Fault
2.2 kΩ
0 mA
4.7 kΩ
5.1 mA - - 25 mA 30.1 mA
Fault - -
1.5 kΩ
16.0 mA 20 mA 36.0 mA