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 11 of 15
15-1) SIL 2 System Wiring for Fault Detection in Standby and Active Mode
–
4 Wire Installation
(Recommended)
The customer is required to wire into both the beacon power supply terminals and also the SIL 2 Relay terminals TB1.
The power supply terminals only need to have the supply power connected. This will be reverse polarity for monitoring mode and
normal polarity for active mode. There is no need to fit an EOL resistor on the power supply terminal as the TB1 is configured to
raise a fault alarm in any situation.
Terminal block TB1 is the output from the SIL 2 monitoring relay. Relay RLY 1-2 provides a closed circuit between TB1 terminals 1 &
2 whilst powered. On detection of a fault event this will become open circuit.
The fault will be seen via the SIL 2 TB1 terminals as soon as the fault occurs in either Active or Standby modes.
When no fault is detected the circuit to the SIL 2 TB1 terminals 1 & 2 will include a factory fitted 3.3K Ohm current sense resistor
(CSR) in series. When the circuit is driven with 24Vdc the detection current seen is ~7.3mA @ 24V.
The only other fault mode is if the cable goes short circuit where a short will be seen by the panel.
Option:
Should the fault event output of RLY1-2 be required to operate as a switch, header J1 can be set to link pins 1 & 2 (see
Figure 13) thereby removing the 3.3k Ohm current sense resistor (CSR) from the circuit.
Note
: a cable short circuit will not be detectable in this configuration.
For one unit only:
Beacon power
supply terminal
block
Current drawn
(mA)
Active Mode
190mA
Standby Mode
25mA
SIL2
TB1 Current
Sense Resistor
value
Current drawn
(mA)
3.3kΩ
7.2mA
On fault mode, current drops to 0 as
circuit goes open.
Figure 13: Schematic of SIL 2 system wiring for fault detection in standby and active mode
–
4 wire installation.
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.
15-2) SIL 2 System Wiring for Fault Detection in Standby Mode Only
–
2 Wire Installation
Cabling is required to the positive '+' and negative '-' power input terminals only. Monitoring will occur in standby mode only whilst
power supply polarity is reversed. An EOL resistor may be added during installation or can be factory fitted. See Table 5 for EOL
resistor value guidance.
The SIL2 monitoring module contains a factory fitted Power Supply Fault Resistor 2.2k Ohm (FR). When a fault is detected the Fault
Resistor will activated. The total measurable resistance of the EOL resistor and Fault Resistor across the power terminals which
already has customer EOL resist
or (2.2kΩ) in place. This will result in a total f
ault detection current of 41.8mA @ 24V but can only
be detected when unit is in Standby Mode.
Important
: - The 2 wire configuration will not warn of a fault whilst in Active mode. A fault will only be detectable in standby mode
when power supply polarity is reversed.
Important
: - The 2-wire configuration requires the J2 header pin to be set to position B (see figure 16). Factory default position is A.
