Appendix B: Application Example - Extech Instruments 48VTR User Manual

Appendix B: Application Example

Maintaining an Oven Temperature of 500
• The controller monitors the oven temperature via the thermocouple.
• The controller compares the actual temperature (PV) to the desired temperature (500
setpoint SV) and throttles the heater as needed to maintain 500
• If the oven temperature reaches the alarm setpoint (A1SP), the controller's alarm
triggers the over-temp alert.
• Program the controller per the steps below.
A1SP (Alarm Setpoint) in 1
o
Set to 600 F. This is the temperature at which the alarm will switch the over-temp alert ON.
nd
Tuning the Controller (2
Use the Auto Tune utility – Refer to the Auto Tune section of this manual. Auto Tune
automatically sets the PID tuning parameters found in the 2
rd
3 Menu Level Parameters
A1Fu (Alarm Function): Set to '2' (High Process Alarm). Relay will trip when
temperature rises above 600
Act (Action): This is the controller's output action. Set to '1' for heating.
o
unit: Set to '1' for F
dp (decimal point): Set to '0' for no decimal point
Ct (Cycle time): Cycle time is the period between output adjustments. Set the Cycle
Time to the longest time possible without causing process oscillations.
tYPe: Set to a '1' since, in this example, a K-type thermocouple is used.
th
4 Menu Level
Unused
6 7 8 9 10
4 5
1 2 3
48VTR REAR
1. AC 90 to 264VAC to Terminals 6 and 7
Note: Wiring shown assumes that the AC source
is powering both the meter and the Heater/ Alarm.
If the external devices require a different AC source
or a require a DC source, the wiring will differ.
o
F (Refer to the diagram for wiring and setup)
st
Menu Level
Menu Level)
o
F turning the over-temp annunciator ON.
Type K
ALARM ANNUNCIATOR
OVER-TEMP
To terminal 6
Additional connections
2. Jump terminal 7 to 4
25 Model 48VTR - Version 5.0 – January 2006
o
F.
nd
Menu Level.
HEATER
OVEN
o