IDEC MicroSmart Pentra - Manual (Page 129)

A PPLICATION E XAMPLES
7-8 FC5A MicroSmart PID Module User’s Manual FC9Y-B1283
Application Example 2
This application example demonstrates the program control for a system using two electric furnaces for
ceramic industries.
• The PID module controls electric furnace 1 with CH0 control and electric furnace 2 with CH1 control using
program control.
• PID control is performed based on the temperature input to the PID module and the program pattern below.
The control output is turned on or off in accordance with the output manipulated variable (MV).
• The program pattern for the program control consists of the following 4 steps.
[Step 0]: Preheat process
Step 0 is the process to gradually raise the set point (SP) to the preheat temperature (100°C) in
60 minutes to evaporate water in the specimen and electric furnace interior. When the elapsed
time in step 0 is 60 minutes, if the process variable (PV) is less than 90°C, the PID module waits
until the temperature reaches 90°C. When the temperature reaches 90°C, the PID module
proceeds to the next step.
[Step 1]: Preheat process
Step 1 is the process to keep the preheat temperature (100°C) constant for 60 minutes.
[Step 2]: Firing process
Step 2 is the process to gradually raise the set point (SP) to the firing temperature (800°C) in 5
hours to prevent the specimen from being damaged by a rapid temperature rise. When the
elapsed time in step 2 is 5 hours, if the process variable is less than 790°C, the PID module waits
until the temperature reaches 790°C. When the temperature reaches 790°C, the PID module
proceeds to the next step.
[Step 3]: Firing process
Step 3 is the process to keep the firing temperature (800°C) constant for 30 minutes.
• PID parameters (proportional band/proportional gain, integral time, derivative time, and ARW) of each step
are automatically calculated using auto-tuning (AT).
• In CH0 control, if the process variable (PV) in step 1 becomes 110°C or higher or if the process variable (PV)
in step 3 becomes 810°C or higher, the upper limit alarm output (Q0) is turned on and the control is disabled.
• In CH1 control, if the process variable (PV) in step 1 becomes 110°C or higher or if the process variable (PV)
in step 3 becomes 810°C or higher, the upper limit alarm output (Q1) is turned on and the control is disabled.
System Configuration and Wiring
Wiring Example of the FC5A-F2MR2 [Relay output type]
Surge Absorber
Surge Absorber
3-phase
Power Supply
Electromagnetic
Switch
Electric
Furnace 2
CH0 Thermocouple
CH1 Thermocouple
+
-
+
-
Power
Supply
PID Module (FC5A-F2MR2)
Electric
Furnace 1
OUT0
OUT1
IN1
IN0
24V DC
Channel
Terminal
No.
Terminal
No.
Channel