Heater Burnout Detection; Cooling Coefficient - Omron E5ZE Operation Manual

Heater Burnout Detection

3-9-2 Cooling Coefficient

3-10 Heater Burnout Detection

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• The following graph shows the output when the E5ZE is operating using ON/
OFF control.
Dead Band Set Value in ON/OFF Control u 0
Output value (%)
Low temperature
Heating hysteresis
The difference between the heating characteristics and cooling characteristics
of the object being controlled may cause control by PID constants to be unsatis-
factory. By changing the cooling coefficient, however, the balance between
heating and cooling can be readjusted.
• The cooling coefficient operates according to the following formula.
Cooling P constant = P constant
• Set cooling coefficients in each memory bank.
• The cooling coefficient setting range is 0.0 to 10.0. The default is 1.0.
• If the cooling coefficient is set to 0.0, the cooling control output value will be 0%.
Leads connected to CT terminal
Heater burnout is detected using the following method.
1. Connect the Current Transformer (CT) for the control point to the corre-
sponding terminal on the CT input terminal block, and pass the power cable
through the hole in the CT.
2. When current flows through the heater power lines, an AC current corre-
sponding to the amount of current flow is generated in the CT. The heater
burnout detection function measures the generated AC current and obtains
the amount of current flowing to the heater.
3. When the heater burns out, the current decreases, and after comparing the
current with the specified heater burnout detection current value, the HB
alarm output will turn ON and the HB indicator will light.
Dead band
Cooling control output
Heating
control
output
High temperature
Set point
Cooling hysteresis
cooling coefficient
Heater power line
Section 3-10
Process value