86
Reference Manual
00809-0200-4728, Rev RA
Section 7: Safety Instrumented Systems (SIS) Certification
April 2015
Safety Instrumented Systems (SIS) Certification
Figure 7-1. Alarm Levels
7.7
644 SIS operation and maintenance
7.7.1
Proof test
to perform Loop Test, Review – Device
Variables, and view Status.
The required proof test intervals depends upon the transmitter configuration and the
temperature sensor(s) in use along with other factors. Refer to the Rosemount 644 FMEDA
report for further information.
7.7.2
Partial proof test
Conducting the Partial Proof Test detects approximately 63% of transmitter DU failures, and
approximately 90% of temperature sensor(s) DU failures, not detected by the 644 safety-certi-
fied automatic diagnostics, for a typical overall assembly coverage of 67%.
1.
Bypass the safety PLC or take other appropriate action to avoid a false trip.
2.
Using Loop Test, enter the milliampere value representing a high alarm state.
3.
Check the reference meter to verify the mA output corresponds to the entered value.
This tests for compliance voltage problems such as a low loop power supply voltage or
increased wiring resistance. This also tests for other possible failures.
Rosemount alarm level
Namur alarm level
Custom alarm level
(3)(4)
(1) Transmitter Failure, hardware or software alarm in LO position.
(2) Transmitter Failure, hardware or software alarm in HI position.
(3) High alarm must be at least 0.1 mA higher than the high saturation value.
(4) Low alarm must be at least 0.1 mA lower than the low saturation value.
Normal Operation
4 mA
20 mA
20.8 mA
high saturation
21.75
(2)
3.9 mA
low saturation
3.75 mA
(1)
Normal Operation
4 mA
20 mA
20.5 mA
high saturation
22.5
(2)
3.8 mA
low saturation
3.6 mA
(1)
Normal Operation
4 mA
20 mA
20.1 - 22.9 mA
high saturation
20.2 - 23.0
(2)
3.7 - 3.9 mA
low saturation
3.6 - 3.8 mA
(1)
Summary of Contents for Rosemount 644
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