Temperature Control Errors - Omron E5ZN Operation Manual

Temperature Control Errors

8-4

Temperature Control Errors

Temperature Does Not Rise
Connections Process value of the E5ZN is abnormal.
Load is not connected to the control output termi-
nal of the E5ZN.
Polarity or wiring of a load is incorrect.
A screw of the terminal block of the E5ZN is loos-
ened and improper contact is resulting.
Power is not supplied to heaters.
Heaters are burnt out or have deteriorated.
Heat capacity of the heater is too small.
Overheating prevention device for the E5ZN is
operating.
Settings E5ZN is in reverse operation mode, instead of
direct operation mode, or vice versa.
PID constants of the E5ZN are incorrect.
E5ZN has not started temperature control.
Control output value of the E5ZN does not
increase because of the restrictions of the MV
limit value.
Cooling fan is operating.
Process Value Exceeds Set Point
Connections Process value of the E5ZN is abnormal.
Load is connected to the incorrect control point of
the E5ZN and is controlling the heaters with the
control output of the incorrect control point.
Relay driven by control output has contact weld.
SSR is short-circuited.
SSR leakage current is flowing into the heaters.
Settings E5ZN is in reverse operation mode, instead of
direct operation mode, or vice versa.
PID constants of the E5ZN are incorrect.
Control output value of the E5ZN does not
increase because of the restrictions of the set MV
limit value.
E5ZN is outputting in manual mode.
Operation Controlled object is radiating heat.
Controlled object is influenced by large overshoot-
ing.
152
Probable cause
Probable cause
Remedy
Refer to 8-3 Temperature Sensing Errors for
appropriate troubleshooting.
Connect a load.
Correct the wiring of the load.
Tighten the screw.
Supply power to the heaters.
Replace the heaters.
• Replace the heater with one having a larger
heat capacity.
• If more than one heater is used and some are
burnt out, replace the heaters.
The set value of the overheating prevention
device must be larger than the set value of the
E5ZN.
Correct the operation mode setting.
• Execute autotuning.
• Set the PID constants of the E5ZN to appropri-
ate values.
Start the temperature control.
Set the MV limit value of the E5ZN to an appropri-
ate value.
Turn OFF the cooling fan.
Remedy
Refer to 8-3 Temperature Sensing Errorsfor
appropriate troubleshooting.
Correct the wiring of the load.
Replace the relay.
Replace the SSR.
Connect a bleeder resistance to the SSR to pre-
vent operation with the SSR leakage current.
Correct the operation mode setting.
• Execute autotuning.
• Set the PID constants of the E5ZN to the val-
ues suitable to the system.
Set the MV limit value of the E5ZN to an appropri-
ate value.
Interrupt the manual mode of the E5ZN.
Execute heating and cooling control.
Refer to the following table regarding overshoot-
ing and undershooting for appropriate trouble-
shooting.
Section 8-4