SActivate new command.
8.7 Secondary Menu
Functions which are used lessoften are accessed within the secondary menu.
The secondary menu isaccessed b ypressing “SET” and “EXIT” simulta-
neouslyand then releasing. The first function in the secondary menu is the
heater powerdisplay.
8.8 Heating Power
The temperature controller controls the temperature of the well by heating or
cooling thewell with the thermoelectric modules. The amount of heating or
cooling powerdepends on the temperature set-point of the well. This heating
(or cooling)power value may be estimated by watching the red/green control
indicatorlight or read directly from the digital display. By knowing the amount
of heating the user can tell if the calibrator is heating up to the set-point, cool-
ing down, or controlling at a constant temperature. Monitoring the percent
heater power will let the user know how stable the well temperature is. With
good control stability thep ercentheating p owershould not fluctuate more than
±1% withinone minute.
The heater powerdisplay is accessed in the secondary menu. Press “SET” and
“EXIT” simultaneously and release. The heater power will be displayed as a
percentageof fullpower.
20.00 C Well temperature
S+E Access heater power in secondary menu
-12 Pct Heater power in percent
Negativenumbers indicate the well is being cooled. -100% means the well is
being cooled atmaximum power. 0 means the well requires neither heating nor
cooling.100% means the well isbeing heated at maximum power.
Toexit out of the secondary menu press “EXIT”. To continue on to the propor-
tional band setting function press “SET”.
8.9 Proportional Band
In a proportionalcontroller such as this, the heater output power is proportional
to the welltemperature over a limited range of temperatures around the
set-point.This range of temperature is called the proportional band. At the bot-
tom of theproportional band the heating is 100%. At the top of the proportional
34 HartScientific
8Controller Operation