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Temperature Control Errors Section 8-4
8-4 Temperature Control Errors
Temperature Does Not Rise
PV Exceeds SP
Probable cause Remedy
Connections PV of the E5ZN is abnormal. Refer to 8-3 Temperature Sensing Errors for
appropriate troubleshooting.
Load is not connected to the control output termi-
nal of the E5ZN.
Connect a load.
Polarity or wiring of a load is incorrect. Correct the wiring of the load.
A screw of the terminal block of the E5ZN is loos-
ened and improper contact is resulting.
Tighten the screw.
Power is not supplied to heaters. Supply power to the heaters.
Heaters are burnt out or have deteriorated. Replace the heaters.
Heat capacity of the heater is too small. • 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.
Overheating prevention device for the E5ZN is
operating.
The set value of the overheating prevention
device must be larger than the set value of the
E5ZN.
Settings E5ZN is in reverse operation mode, instead of
direct operation mode, or vice versa.
Correct the operation mode setting.
PID constants of the E5ZN are incorrect. • Execute autotuning.
• Set the PID constants of the E5ZN to appropri-
ate values.
E5ZN has not started temperature control. Start the temperature control.
Operation after power ON (initial setting level) is
set to STOP.
Set the RUN/STOP parameter (operation level) to
RUN.
The initial setting level, communications setting
level, or advanced function setting level is
selected.
Move to the operation level, and set the RUN/
STOP parameter to RUN.
Control output value of the E5ZN does not
increase because of the restrictions of the MV
limit.
Set the MV limit of the E5ZN to an appropriate
value.
Cooling fan is operating. Turn OFF the cooling fan.
Probable cause Remedy
Connections PV of the E5ZN is abnormal. Refer to 8-3 Temperature Sensing Errors for
appropriate troubleshooting.
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.
Correct the wiring of the load.
Relay driven by control output has contact weld. Replace the relay.
SSR is short-circuited. Replace the SSR.
SSR leakage current is flowing into the heaters. Connect a bleeder resistance to the SSR to pre-
vent operation with the SSR leakage current.
Settings E5ZN is in reverse operation mode, instead of
direct operation mode, or vice versa.
Correct the operation mode setting.
PID constants of the E5ZN are incorrect. • Execute autotuning.
• Set the PID constants of the E5ZN to the val-
ues suitable to the system.
Control output value of the E5ZN does not
increase because of the restrictions of the set MV
limit.
Set the MV limit of the E5ZN to an appropriate
value.
E5ZN is outputting in manual mode. Interrupt the manual mode of the E5ZN.
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