European Safety Systems Ltd.
Impress House, Mansell Road, Acton, London W3 7QH
www.e2s.com
Tel: +44 (0)208 743 8880
Document No. D157-00-671-IS
Issue 2
06-03-2023
Sheet 7 of 14
11) SIL 2 Instruction/Safety Manual
Figure 12 - The SIL 2 Module monitors the Sounder and interfaces to the customer plant.
Warning
–
To maintain the integrity of the SIL 2 units the system must be installed, commissioned and used within the parameters
outlined in this manual. Failure to comply could result in an unintended unit operation or function.
Warning
–
The unit must be powered in either Standby or Active modes to comply with the SIL 2 approval requirement.
If the power is disrupted the unit must be allowed to go through the commissioning cycle to reset.
Failure to complete the commissioning cycle and continued disruption in the power supply will generate a fault state
which will require the sounder to be reset (see section 15-4).
Warning
–
Only the alarm tones specified in section 14 may be selected for use in SIL2 compliant systems.
SIL 2 System Description
The SIL 2 module monitors the function of the device and
provides feedback to the control panel. A fault condition can
be communicated by two methods:
•
4 wire installation can be seen as per section 15-1.
A SIL 2 system wiring for fault detection in standby
and active mode with independent fault contacts.
•
2 wire installation can be seen as per section 15-2.
A SIL 2 system by the introduction to the monitoring
circuit and linking in an end of line resistor can only
register the fault in standby mode.
12) SIL 2 System Terms and Function
The SIL 2 Sounder Unit Monitors
•
Standby mode and Active mode
•
Health status of power supply
•
Sounder correct function and tone pattern
The SIL 2 sounder operates as part of a SIL 2 system.
The sounder will after commissioning remain powered in
Standby mode
(reverse polarity) until the sounder is required
to operate. When the signaling device is required to operate
the polarity is changed to normal supply and the sounder will
go into
Active mode
where it will start to sound the correct
tone. When periodically testing the system and sounders
operation is put into
Active mode
.
The system panel or PLC will control whether the system is in
either of the main two operational modes.
Standby Mode
–
This is where the power supply polarity is
reversed so negative (
–
ve) is feed to the positive (+) sounder
terminal and positive (+) is feed to the negative (
–
ve) sounder
terminal.
In Standby mode the sounder will not sound the tone but the
SIL 2 unit is monitoring power supply and is set-up ready to go
to Active (alarm) mode.
Power relay RLY1-1 will be open whilst SIL 2 relay RLY1-2 will
be closed contact between terminals 1 & 2.
If power is disrupted the SIL 2 unit will go into
Fault mode
, in
fault mode the Power relay RLY1-1 will close whilst SIL 2 relay
RLY1-2 will become open circuit between terminals 1 & 2.
Active Mode
–
This is where the power is in normal polarity,
positive (+) supplied to the positive (+) sounder terminal and
negative (
–
ve) is supplied to the negative (
–
ve) sounder
terminal.
In Active mode the alarm horn sounder will output the selected
alarm tone. The SIL 2 module checks for the correct alarm tone
output and the functionality of the alarm tone signal generation
process.
Power relay RLY1-1 will be open whilst SIL 2 relay RLY1-2 will
be closed contact between terminals 1 & 2.
J3 HEADER PIN
