Fluke 9132 User Manual page 27

9132 Portable IR Calibrator
User's Guide
26
set-point. This range of temperature is called the proportional band. At the bot-
tom of the proportional band the heater output is 100%. At the top of the pro-
portional band the heater output is 0. Thus as the temperature rises the heater
power is reduced, which consequently tends to lower the temperature back
down. In this way the temperature is maintained at a fairly constant
temperature.
The temperature stability of the well and response time depend on the width of
the proportional band. If the band is too wide the well temperature deviates ex-
cessively from the set-point due to varying external conditions. This is because
the power output changes very little with temperature and the controller cannot
respond very well to changing conditions or noise in the system. If the propor-
tional band is too narrow the temperature may swing back and forth because
the controller overreacts to temperature variations. For best control stability the
proportional band must be set for the optimum width.
The proportional band width is set at the factory to about 25.0°C. The user may
alter the proportional band width if he desires to optimize the control character-
istics for a particular application. However, we recommend the proportional
band be changed only by knowledgeable personnel.
The proportional band width is easily adjusted from the front panel. The width
may be set to discrete values in degrees C or F depending on the selected units.
The proportional band adjustment can be accessed within the secondary menu.
Press "SET" and "EXIT" to enter the secondary menu and show the heater
power. Then press "SET" to access the proportional band.
S+E
Access heater power in secondary menu
Flashes
SEC
heater power
12.0P Heater power in percent
S
Access proportional band
Flashes
PROP
heater power
Proportional band setting
4.1
To change the proportional band press "UP" or "DOWN".
New proportional band setting
10.0
To accept the new setting press "SET". Press "EXIT" to continue without stor-
ing the new value.
for secondary menu and then displays the
for secondary menu and then displays the