Rosemount 5401, Справочное руководство

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Reference Manual
00809-0100-4026, Rev FA
July 2009
Rosemount 5400 Series
C-2
The Distance Offset (G) is the distance between the upper reference point
and the flange. The flange is referred to as the Transmitter’s Reference
Point). The Distance Offset can be used to specify a reference point at the top
of the tank. Set the Distance Offset to zero to identify the lower side of the
device flange as the upper reference point. The Distance Offset is defined as
positive if an upper reference point above the Upper Reference Point is used.
Minimum Level Offset (C)
The Minimum Level Offset (C) defines a lower null zone which extends the
measurement range beyond the Lower Reference Point to the tank bottom.
The Minimum Level Offset is the distance between the Lower Reference Point
(Level=0) and the minimum accepted level at the tank bottom. Set the
Minimum Level Offset to zero to use the tank bottom as the Lower Reference
Point. This case corresponds to the standard Tank Geometry configuration.
Note that the Tank Height must be measured to the Lower Reference Point
regardless if it is located at the tank bottom, or at an elevated point.
Hold Off Distance
This parameter should only be changed if there are disturbing objects close to
the antenna. No valid measurements are possible above the Hold Off
Distance. By increasing the Hold Off Distance, the measuring range is
reduced. See “Hold Off Setting” on page C-13 for more information.
Calibration Distance
The Calibration Distance is defaulted to zero. It is used to adjust the
transmitter so measured levels match hand-dipped or otherwise known
product levels. Normally, a minor adjustment is necessary. There may, for
example, be a deviation between the actual tank height and the value from
tank drawings, which are usually stored in the transmitter database.
Non-metallic (e.g. plastic) vessels and installation geometry may introduce an
offset for the zero reference point. This offset may be up to
±
10 mm. The
offset can be compensated for using Calibration Distance.