Level Calibration - ABB LMT100 Operation Instructions Manual

48

Level Calibration

The LMT Series is a digitial transmitter with no routine
calibration or reconfiguration required If a recalibration is
required, this can be done using the HART signal (via DTM,
EDDL) or with the menu driven HMI display
The most important term to understand and master the
calibration process is the Sensor Value (SVL) SVL could be seen
from two perspectives:
• Technical – SVL is the output parameter of the factory trim,
which gets mapped to the propagation time
• Practical – The SVL could be interpreted as the "Raw" Level
before any user specific calibration is applied to the
instrument, and its values always increases in the direction to
the tip of the probe, independently of the mounting
orientation
Figure 35 Bottom & Top Mount Charts
In other words, the SVL could be seen as the level output of the
instrument based only on the factory trim After the factory
trim the SVL at any given point on the probe will remain
unchanged for the life of the instrument (unless trimmed again
at later time) and it is not affected by any level calibration,
offset or linearization applied by the user
Notice that Calibration Point 00 is always located above
Calibration Point 01, which means Point 00 always corresponds
to "HIGHER" level value than Point 01
L M T S E R I E S | M A G N E TO S T R I C T I V E L E V E L T R A N S M I T T E R | O I/ L M T 1 0 0/ 2 0 0 - E N R E V. B
Figure 36 Calibration Points
By default after the trim the SVL & LVL are aligned at the
calibration points 00 & 01 matching each other values but
during the Level Calibration SVL could be mapped to different
Level Values (LVL) that don't violate the validation rule for Level
calibration: The LVL span must be within ±5% the SVL span
LMT Calibration through HMI
STEP 1:
From the "Level Information" screen press
"Access Level" menu
STEP 2:
Press
Press "Select"
STEP 3:
Press
Press "Select"
or to navigate to "Advanced"
or to navigate to the Calibrate menu
to enter the menu
to switch to the