Appendix B: Heating Process Example - Extech Instruments 96VFL Series User Manual

16. Appendix B: Heating Process Example

Controlling Oven Temperature
•
The thermocouple TC input (terminals 9 and 10), control output relay (16 and 17), and
alarm relay (11 and 12) are wired to the process as shown above. Note that the AC
power pictured represents an external power source. The controller power wiring
terminals (19 and 20) are not pictured.
•
Configure the controller per the Programming Menu instructions below.
•
The user adjusts the setpoint (SV) to the desired oven temperature (500
To set the SV, use the SHIFT (<) key to select a digit and then the up/down arrows to
adjust it. Press SET when done.
•
The thermocouple senses oven temperature and displays it on the front panel (PV).
•
The controller output switches the heater ON/OFF, as needed, to maintain the setpoint.
•
If the oven temperature reaches the alarm setpoint, the alarm relay triggers an alert.
•
Note that you could wire the alarm relay in series with the control relay as an
emergency shut-down configuration if desired.
Programming the Controller
• A1Fu (Alarm Function) Menu 4: Set to '2' (High Process Alarm). The Alarm relay will trip
when the temperature reaches 600
• Act (Action) Menu 4: Control output action. Set to '1' for heating.
• Units Menu 4: Set to '1' for
• dp (decimal point) Menu 4: Set to '0' for no decimal point.
• Ct (Cycle time) Menu 3: Set to longest time possible without causing process oscillations.
• Type (Input type) Menu 4: Set a thermocouple input type.
• A1SP (alarm 1 setpoint) Menu 1: Set the alarm setpoint to 600
• AT (Auto Tune) Menu 1: Set to 'YES:1' to start an Auto Tune session.
FIGURE 16.1 - CONTROLLING AN OVEN WITH A 96VFL
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F.
o
F, triggering the over-temperature alert.
33
o
F, for example).
o
F.
VFL Series User Manual v2.0 10/20