may be estimated by watching the red/green control indicator light or read di-
rectly from the digital display. By knowing the amount of heating, the user can
tell if the bath is heating up to the set-point, cooling down, or controlling at a
constant temperature. Monitoring the percent heater power allows the user to
determine the stability of the bath temperature. With good control stability the
percent heating power should not fluctuate more than
±
1% within one minute.
The heater power display is accessed in the secondary menu. Press “SET” and
“EXIT” simultaneously and release. The heater power displays as a percentage
of full power.
S+E
Access heater power in secondary menu
12 Pct
Heater power in percent
To exit out of the secondary menu press “EXIT”. To continue on to the propor-
tional band setting function press “SET”.
E
Return to temperature display
9.9
Proportional Band
In a proportional controller such as this the heater output power is proportional
to the bath temperature over a limited range of temperatures around the
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 bath 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.
6331 Calibration Bath
User’s Guide
46
