Sis Operation And Maintenance; Proof Test; Partial Proof Test - Emerson Rosemount 644 Reference Manual

Section 7: Safety Instrumented Systems (SIS) Certification
April 2015
Figure 7-1. Alarm Levels
3.75 mA
3.6 - 3.8 mA
(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.
7.7

644 SIS operation and maintenance

7.7.1

Proof test

The following proof tests are recommended. In the event that an error is found in the safety
functionality, proof test results and corrective actions taken must be documented at
www.rosemount.com/safety. Use
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.
2.
3.
86
Rosemount alarm level
(1)
4 mA
3.9 mA
low saturation
(1)
3.6 mA 4 mA
3.8 mA
low saturation
Custom alarm level
(1)
4 mA
3.7 - 3.9 mA
low saturation
Bypass the safety PLC or take other appropriate action to avoid a false trip.
Using Loop Test, enter the milliampere value representing a high alarm state.
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.
Normal Operation
20 mA
Namur alarm level
Normal Operation
20 mA
(3)(4)
Normal Operation
20 mA
high saturation
Table C-1 on page 161
Safety Instrumented Systems (SIS) Certification
Reference Manual
00809-0200-4728, Rev RA
(2)
21.75
20.8 mA
high saturation
(2)
22.5
20.5 mA
high saturation
(2)
20.2 - 23.0
20.1 - 22.9 mA
to perform Loop Test, Review – Device