42
•
The following graph shows the output when the E5ZE is operating using ON/
OFF control.
Output value (%)
Dead band
Low temperature
Set point
High temperature
Cooling control output
Heating
control
output
Process value
Heating hysteresis
Cooling hysteresis
Dead Band Set Value in ON/OFF Control
0
3-9-2 Cooling Coefficient
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
cooling coefficient
•
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%.
3-10 Heater Burnout Detection
Leads connected to CT terminal
Heater power line
Heater burnout is detected using the following method.
1, 2, 3...
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.
Heater Burnout Detection
Section 3-10
