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output if the temperature increased less than 3 °C (5 °F) after the controller was
powered up for 5 minutes. The alarm buzzer will be turned on at the same time.
The display will flashing OPEN (oPEn).
Hy. Hysteresis band (or dead band). This parameter is used for on/off control only.
In the on/off heating mode, the heater will be turned off when T = SV, and turned
on again when T<SV-Hy. e.g. If SV=100 °C. Hy=3.0 °C, the heater will heat until
temperature reaches 100.0 °C. It will be turned on again when temperature drops
below 97.0 °C. For the cooling mode, the compressor will be turned off when
T=SV. It will be on again when T>SV+Hy.
CooL. When Cool=0, the controller is set for heating control (reverse action).
When Cool=1, the controller is set for cooling control (direct action).
Out, Output power reduction. It is expressed as a percentage value. This function
will allow you to control the maximum output power delivered by the heater. For
example, if you set Out=50 and your heater is 1000 watts, the output will use 50%
of the 1000 watts as the full output. It treats the 1000W heater as a 500W heater.
When the PID algorithm determines 50% output value, the actual power output
will be 250 watts. This function can be used in two situations.
1) When you have a very powerful heater and are using a very small pot of water
to cook at very low temperature, for example, a 1400 watts heater with a one litter
(1 qt) pot of water at 130 °F. The heater is too powerful for the small water volume.
The moment it is on, it releases too much energy and overshoots the temperature.
Although it is still possible to stabilize the temperature with proper PID parameters,
it is much easier to control if you limit the maximum output to 25%. Ideally, an
optimized temperature control system should consume about 25 % of the heater
power at set temperature (steady state), for example, if you found out that only 50
watts of energy is needed to maintain the temperature at 60 °C (141°F), ideally
you should use only a 200 watts heater for the job. Too much power will make the
system over react too quickly. Too little power will make the system too slow in
response. By using the OUt function, you can make the 1400 watts heater to act
as a 200 watt heater for stable temperature control.
2) When the cooker consumes more power than controller can handle, for
example, if you have a 12A, 120V AC heater and your cooker contains more than
38 liter (10 gallon) of water. It might take more than 90 minutes of full power
heating for controller to heat up the pot. Long time of full power operation might
cause the controller to over heat. You can set the output to 80%. It will prevent the
controller from over heating from staying at full power too long. For details, please
see Appendix 1.
C-F, Display unit setting. You can set the display either Celsius or Fahrenheit.
This group of parameters is accessed by input code 155. Figure 9 is the flow chart that
shows how they can be changed.
