ABB LLT100, Руководство по функциональной безопасности

Страница: 21 / 32

Installation and commissioning
21
Enabling/Disabling the write protection
The device shall be write-protected for the safety operation. This could be performed through the
following steps:
1
Remove the nameplate by releasing the holding screw lying on the bottom left corner.
2
Use a suitable screwdriver to press the switch down fully.
3 Turn the switch clockwise by 90°.
To deactivate the switch and remove the write protection, push it down slightly and turn
counterclockwise by 90°.
High/Low alarm configuration
The LLT100 alarm state must be configured to ensure corresponding current value between the device
and the DCS. The low alarm limit can be set from 3.5 to 3.6 mA and the high alarm limit between 21.0
and 21.6 mA.
1 From the Process Alarm menu, select Process Alarm Limits > Current Out > Low Alarm or High
Alarm .
2
From there, edit the value as necessary, based on the information above.
3
Press
OK
.
Verify safety function
1
Verify and record the conditions as they are found prior to checking the safety function: write
protection is on/off, instrument parameters.
2 Disable write protection before power up.
3 Check the current out precision by simulating current out and measure it with a multimeter. This
could be performed by using an EDD/DTM interface or the HMI. The current out test shall test 4 mA
and 20 mA at least.
4
Verify the alarm state configuration and alarm value configuration (3.5–3.6 mA and 21.0–21.6 mA).
Simulate an alarm to check whether the alarm current is what was set via multi-meter.
5
Enable write protection and power down. If no alarm is issued after system startup, then the safety
function is ensured during run-time.