DESCRIPTION AND OPERATION
FUNCTIONAL OPERATION
2 - 2
WBPEEUI110505A0
Cell and Characterization Board Assembly
Type PTSDL level transmitters use an electrically isolated dif-
ferential reluctance cell as the sensing device. The cell has two
half-shells clasping a measuring diaphragm, centered and
welded at the edges under stress. A core is welded to each side
and at the center of the diaphragm. The diaphragm has spiral
ridges for pressures
≤
90 kilopascals (
≤
360 inches of water) or
is flat and trimmed for pressures
>
90 kilopascals (
>
360 inches
of water). These distinctive diaphragms provide symmetry,
flexibility and accuracy under static pressure (Fig.
Two inductive coils are at each side of the cores in the two
half-shells. Two welded walls isolate them from the fill fluid.
Two isolating diaphragms, welded to the edges, isolate the
measuring diaphragm to protect against corrosion and
overloads. A welded housing protects the cell from the
surroundings.
The pressure, transmitted by the isolating diaphragms and fill
fluid (silicone oil or fluorinated oil), moves the measuring dia-
phragm. An AC voltage excites the two series coils. The mid-
point voltage of these coils varies as a function of the
movement of the magnetic cores welded to the measuring
diaphragm.
Figure 2-2. Cell and Characterization Board Assembly
T 02 2 09 A
C H A R AC T E R IZ ATIO N
B O A R D
LE A D W IR E S
C O IL S
IS O L AT IN G
D IA P H R AG M
M E AS U R IN G
D IA P H R AG M
IS O L AT IN G
D IA P H R AG M
M AG N E T IC
C O R E S
F ILL FL U ID
Summary of Contents for Platinum standard Series
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