ThermoWorks 9150-X HART SCIENTIFIC 9150 THERMOCOUPLE FURNACE - Manual (Page 30)

”EXIT” simultaneously and release. The heater power is displayed as a percent-
age of full power.
962.4 Well temperature
S+E
Access heater power in secondary menu
100.0 P Heater power in percent
To exit out of the secondary menu press “EXIT”. To continue on to the
set-point voltage setting function press “SET”.
8.7 Set-point Voltage
The set-point voltage is displayed for informational purposes and is used to cal-
ibrate the instrument.
The value of the set-point voltage changes when the set-point temperature is
changed and also when DC1 and DC2 are adjusted.
S+E
Access heater power in secondary menu
100.0 P Heater power in percent
S
Access set-point voltage
11.934U Set-point voltage in millivolts
To exit out of the secondary menu, press “EXIT”. To continue on to the propor-
tional band setting function press “SET”.
8.8 Proportional Band
In a proportional controller such a this the heater output power is proportional
to the well temperature over a limited range of temperatures around the
set-point. This range of temperature is called proportional band. At the bottom
of the proportional band the heater output is 100%. At the top of the propor-
tional 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 deviation
is because the power output changes very little with temperature and the con-
29
8 Controller Operation
Set-point Voltage