Troubleshooting From Symptoms: Temperature Control Errors - Omron CJ Series Operation Manual

Troubleshooting
5-2-2

Troubleshooting from Symptoms: Temperature Control Errors

Temperature Does Not Rise
Step
Connection The measured temperature is incorrect.
There is no load connected to the control output
terminals.
The load's polarity is reversed or the load is wired
to the wrong terminals.
The terminal screws are loose so there is poor
contact between the wires and terminals.
The heater's power supply is not ON.
The heater circuit is burned out or damaged.
The heater's heat output is insufficient.
An overheating protection device is operating.
Settings The forward operation/reverse operation setting is
incorrect
The PID constant settings are not correct.
Temperature control has not been started.
A cooling fan is operating.
Measured Temperature Higher than Control Temperature
Step
Connection The measured temperature is incorrect.
The load is connected to the wrong control loop,
so the heater is being controlled by another loop's
control output.
The contacts are fused in the relay operated by
the control output.
There is a short circuit in the relay operated by the
control output.
Current is flowing to the heater because of leak-
age current through the relay operated by the con-
trol output.
Settings The forward operation/reverse operation setting is
incorrect.
The PID constant settings are not correct.
Usage There is excessive overshooting.
Possible Cause
Possible Cause
Remedy
Refer to 5-2-1 Troubleshooting from Symptoms: Mea-
surement Errors for troubleshooting directions.
Connect a load.
Wire the load correctly.
Tighten the terminal screws.
Turn ON the heater's power supply.
Replace the heater with a good one.
• Replace the heater with one that has a higher output.
• When using two or more heaters, check whether one
is burned out. Replace if necessary.
Increase the overheating protection device's tempera-
ture setting so it is higher than the Temperature Control-
ler Unit's set point.
Correct the setting.
• Perform autotuning.
• Make the correct PID constant settings manually.
Start temperature control.
Turn OFF the cooling fan.
Remedy
Refer to 5-2-1 Troubleshooting from Symptoms: Mea-
surement Errors for troubleshooting directions.
Wire the load correctly.
Replace the relay with a good one.
Replace the relay with a good one.
Connect a bleeder resistor to prevent operation due to
the leakage current.
Correct the setting.
• Perform autotuning.
• When autotuning is completed, refresh the PID con-
stants properly so that the Unit operates with the cal-
culated PID constants.
• Make the correct PID constant settings manually.
Refer to Excessive Overshooting or Undershooting on
page 80 for troubleshooting directions.
Section 5-2
79