Vaisala PR-23 Series - Optical Image with VD; Diagnostic Values; Figure 30 Optical Images with VD

6.4.2 Optical image with VD
Vertical Borderline Image Detection (VD) is used in a sugar vacuum pan. With vertical
borderline the optical image is without IDS, and the sides of the optical image are straight
and slightly sloping. This is achieved programmatically, the optical module in the sensor is
the same as for a PR‑23‑GP without the ‑VD option.
Empty pipe Normal conditions
Figure 30 Optical images with VD
6.4.3
Diagnostic values
The values at the left of the graph are used for diagnostic purposes:
• CONC is the final concentration value including field calibration adjustment, see Figure
39 (page 73).
• TEMP, see Temperature measurement (page 58).
• CCD gives the position of the shadow edge on CCD in %.
• nD is the refractive index value n
D
from the sensor.
• CALC is the calculated concentration value without field calibration adjustment, Field
calibration (page 75).
• QF or Quality Factor is a value in the range 0 … 200. The QF value depends on process
medium optical properties. A typical good value is 100, but there are process media
where 50 is acceptable. The QF value should stay constant during the process. Falling
QF value may indicate prism coating.
• LED is a measure of the amount of light from the light source in %.
• HD TMP is the sensor head temperature, see Temperature measurement (page 58).
• HD HUM is the sensor head humidity, see Sensor head humidity (page 58).
• I_SNS value shows the current to sensor, the nominal value is 40 mA.
• DTR TMP is the indicating transmitter temperature, see Temperature measurement
(page 58).
• DTR V1 gives the voltage from the power module, the nominal value is 24 V.
• DTR V2 gives the DC supply voltage, the nominal value is 3.3 V.
Chapter 6 – Startup and use
57