91
Reference Manual
00809-0100-4140, Rev AA
January 2017
baseline and outside the user configured threshold, the level detector can generate a HART
alert or analog alarm.
To make use of this diagnostic, the user must first create a baseline characteristic for the
electrical loop after the level detector has been installed. The loop is automatically
characterized with the push of a button. This creates a linear relationship for expected
terminal voltage values along the operating region from 4 – 20 mA (see
).
Figure 5-2. Baseline Operating Region
A. Terminal voltage
B. Output current
Overview
The Rosemount 2140 and 2140:SIS Level Detectors (“level detectors”), with Extended
Features Packages, are shipped with the
Power Advisory
function switched off and without
any loop characterization performed. After the level detector is installed and powered-up,
the loop characterization must be performed for Power Advisory to function.
When the user initiates a loop characterization, the level detector checks to see if the loop
has sufficient power for proper operation. Next, the output is driven to 4 and 20 mA points
to establish a baseline and determine the maximum allowable terminal voltage deviation.
After this is complete, the user enters a sensitivity threshold called “Terminal Voltage
Deviation Limit”. A check is made to make sure this threshold value is valid.
With the loop characterized and Terminal Voltage Deviation Limit is set, the Power Advisory
function actively monitors the electrical loop for deviations from the baseline. Now, the
level detector generates an alert or alarm whenever the terminal voltage changes (relative
to the expected baseline value) and exceeds the Terminal Voltage Deviation Limit.
Note
Power Advisory monitors and detects changes in the terminal voltage from expected values
to detect common failures. It is not possible to predict and detect all types of electrical
failures on the 4-20 mA analog output. Therefore, Emerson cannot absolutely warrant or
guarantee that Power Advisory will accurately detect failures under all circumstances.
10.5
4 mA
20 mA
B
A
42.5
Summary of Contents for Rosemount 2140
Page 2: ......
Page 8: ...VI Reference Manual 00809 0100 4140 Rev AA Contents January 2017 Contents ...
Page 14: ...4 Reference Manual 00809 0100 4140 Rev AA Introduction January 2017 Introduction ...
Page 112: ...102 Reference Manual 00809 0100 4140 Rev AA Troubleshooting January 2017 Troubleshooting ...
Page 143: ......