ThermoWorks 9009-B INDUSTRIAL DUAL-BLOCK CALIBRATOR - Manual (Page 27)

7.4 Secondary Menu
Functions which are used less often are accessed within the secondary menu.
The secondary menu is accessed by pressing “SET” and “EXIT” simulta-
neously and then releasing. The first function in the secondary menu is the
heater power display. (See Figure 3 on page 20.)
7.5 Heater Power
The temperature controller controls the temperature of the well by pulsing the
heater on and off. The total power being applied to the heater is determined by
the duty cycle or the ratio of heater on time to the pulse cycle time. By knowing
the amount of heating the user can tell if the calibrator is heating up to the
set-point, cooling 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 the percent heating power should not fluctuate
more than
±1% within one minute.
Note: For the Cold Side, negative numbers indicate the well is being cooled.
When the display reads, –100 P, the well is being cooled at maximum power.
When the display reads, 0 P, the well is neither heating nor cooling. When the
display reads, 100 P, the well is being heated at maximum power.
For the hot side, when the display reads, 0 P, maximum cooling is occurring
(no heater power is applied). The power percentage is never negative on the hot
side.
The heater power display is accessed in the secondary menu. Press “SET” and
“EXIT” simultaneously and release. The heater power will be displayed as a
percentage of full power.
100.0 C
Well temperature
S
+
E
Access heater power in secondary menu
SEC Flashes for secondary menu and then displays the
heater power
13.0 P
Heater power in percent
To exit out of the secondary menu press and hold “EXIT”. To continue on to
the proportional band setting function press “SET”.
7.6 Proportional Band
In a proportional controller such as this the heater output power is proportional
to the well temperature over a limited range of temperatures around the
23
7 Controller Operation
Secondary Menu