4. The setup parameters must be verified (as described in
Using the alarm relay contact for alerting
), and the function of the
Rosemount 975 flame detector (flame detection, function of the 0-20 mA interface,
relay functions) must be checked completely.
5. The function of the Rosemount 975HR Flame Detector (flame detector, function of
the 0-20 mA interface, and relay functions) must be checked completely.
E.2.2
Using the 0-20 mA interface for alerting
The following parameters shall be set:
•
Automatic built-in test: On
•
Connected to 0-20 mA terminals
The following allowed output current must be supervised with an accuracy of ±5 percent.
•
Normal state: 4 mA
•
Warning state: 16 mA
•
Alarm state: 20 mA
The output current must be supervised regarding the over-and under run of the 0-20 mA.
The 0-20 mA can be used as low and high demand mode.
E.2.3
Using the alarm relay contact for alerting
The following parameters shall be set:
•
Automatic built-in-test: On
•
Connected to normally closed (N.C.) contact of alarm relay terminals
•
Connected to fault relay terminals
The relay contacts (alarm and faulty relay) must be protected with a fuse rated at 0.6 of
the nominal specified relay contact current.
The maximum contact rating that is allowed per SIL-2 is 30 Vdc.
The contact of the alarm relay opens if there is a fire alarm.
During the forwarding and evaluation of the alarm, the relay contact opens.
The alarm relay can be used as low demand only.
E.2.4
Other
1. The complete function of the flame detector (flame detection, function of the
0-20 mA interface, and the relays) must be examined at least every six or twelve
months (see
) when the flame detector must be
switched OFF and ON.
2. The window of the sensor must be examined at appropriate time intervals for
partial contamination.
SIL-2 features
Reference Manual
June 2021
00809-0100-4976
76
Emerson.com/Rosemount
Legacy
