Level Measurement; Interface Between Two Products; Relative Density - Honeywell FlexLine SmartServo 954 Service Manual

PRINCIPAL OF SERVO MEASUREMENT

Level measurement

Interface between two products

Relative density

Part No.: 4417340 Revision 1
A level variation of product, in which the displacer is partially immersed,
causes a change in buoyancy, which will be detected by the force
transducer. The resulting difference between measured and desired
value will cause a variation in the position of the stepper motor and
consequently raise or lower the position of the displacer until the
measured value equals the desired value.
To avoid oscillations, a certain hysteresis and integration time is
software adjustable. This results in a stable and accurate averaged level
measurement.
The stepper motor turns one revolution for every 10 mm of vertical
movement of the displacer.
One revolution is divided into 200 steps, therefore one step is equivalent
to 0.05 mm. This resolution is direct consequence of the stepper motor
principle. The correct functioning of the stepper motor is continuously
checked. This is achieved by decoding the unique pattern of an encoder
disk mounted on the motor shaft.
Measurement of the interface between two products is achieved by
sending an interface command to the gauge. This causes the stepper
motor processor to move the displacer to a position where the apparent
weight of the displacer matches a pre-programmed set point.
To measure the relative density, the displacer is positioned at specific
heights and the apparent weight of the displacer at each height is
measured. Knowing the volume of the displacer, its weight in air, and
the measured apparent weight, the relative density of the product at
each position of the displacer can be calculated. The software for the
density measurement is available as an option.
Service Manual
954 SmartServo FlexLine
13