Calibration Bath
Controller Operation
37
figure 8.eps
Figure 8. Bath Temperature Fluctuation at Various Proportional Band Settings
The proportional band should be wider when the higher power setting is used so
that the change in output power per change in temperature remains the same.
The proportional band should also be wider when the fluid viscosity is higher
because of the increased response time.
The proportional band width is easily adjusted from the bath front panel. The
width may be set to discrete values in degrees C or F depending on the selected
units. The optimum proportional band width setting may be determined by
monitoring the stability with a high resolution thermometer or with the controller
percent output power display. Narrow the proportional band width to the point at
which the bath temperature begins to oscillate and then increase the band width
from this point to 3 or 4 times wider. Table 3 lists typical proportional band
settings for optimum performance with a variety of fluids at selected
temperatures.
Table 3. Proportional Band- Fluid Table
Fluid
Temperature
Heater Setting
Proportional Band
Stability
Water 30.0
°
C Low
0.04
°
C
±
0.001°C
Water 60.0
°
C Low
0.04
°
C
±
0.001°C
Eth-Gly 50 %
35.0
°
C Low
0.05
°
C
±
0.001°C
Eth-Gly 50 %
60.0
°
C Low
0.05
°
C
±
0.001°C
Eth-Gly 50 %
100.0
°
C High
0.4
°
C
±
0.002°C
Oil (5cs)
35.0
°
C Low
0.1
°
C
±
0.003°C
Oil (5cs)
60.0
°
C Low
0.2
°
C
±
0.002°C
Oil (5cs)
100
°
C Low
0.2
°
C
±
0.003°C