Secondary Menu; Heater Power; Proportional Band - Fluke 7341 User Manual

Press "SET" to activate the new program control command and return to the
temperature display.
S
9.7

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.
9.8

Heater Power

The temperature controller controls the temperature of the bath 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. This value
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 lets the user know
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 is displayed as a percent-
age of full power.
S+E
12 Pct
To exit out of the secondary menu press "EXIT". To continue on to the propor-
tional band setting function press "SET".
E
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.
Activate new command
Access heater power in secondary menu
Heater power in percent
Return to temperature display
9 Controller Operation
Secondary Menu
45