Auber WS-1500EBPM Instruction manual

Operation Instruction Manual
WS-1500EBPM
Precision PID Temperature Controller
Version 1.1
Auber Instruments
5755 North Point Parkway, Suite 99
Alpharetta, GA 30022
770-569-8420
www.auberins.com
May, 2013
Introduction
Thank you for purchasing the Auber WS series temperature controller. We sincerely
appreciate your decision and trust that our machine will meet your expectations in both
the quality of the result and the value of our product. While we are delighted that you may
be anxious to operate the controller for your project, a few minutes of your time reading
through this manual will only serve to enhance your experience in the months and years
ahead. In particular, we urge you to read through the safety warnings below. Although
this plug-and-play controller is very easy to operate, the process involves high
temperature and high wattage appliances, and your safety is paramount.
SAFETY WARNINGS
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This controller is designed only to be used with devices that have limited power
and their own thermal cutoff protection, such as a thermostat or thermal fuse in
case of controller failure.
Do not place any objects on the top of controller surface which is used to vent
excess heat during its operation.
The maximum electric current this controller can handle is 15 Ampere. For 120
volt AC in US and Canada, this limits the heater power to 1800 watts. Due to its
compact size and the splash proof design for kitchen applications, the controller
has a limited ability to dissipate the heat generated by the internal solid state relay
during the initial heat up. The initial full power heat up process cannot be more
than 90 minutes. If you system need take longer time to warm up, please read
Appendix 1 “Managing the heat generated by the controller”
Always place the sensor in the controlled subject when the controller is on.
Before turning on the controller, please make sure the sensor is placed inside the
container to be controlled. Leaving the sensor outside will form an open loop
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operation. If the sensor is left outside, the controller will assume the temperature
is low even if the controlled subject is already very hot. The controller will provide
full power to the heater. It will not only overheat the controller, but also damage
your appliance possibly causing a fire. If the sensor is not permanently mounted
on the system and is left outside of the system, this could become a potential
problem, you should enable the open loop alarm function (see page 11 for
details).
This controller is designed to control the devices recommended by Auber
Instruments only. Using it to control a not recommended device can be dangerous
and cause fire. Auber Instruments is not liable for damages caused by misuse of
the controller. If you are not sure the controller can be used, please contact Auber
Instruments before use.
If an abnormal display or noise is observed, turn the controller off, unplug the
power cord and contact the manufacturer before using it again.
Clean the controller only when it is cool and unplugged.
Do not allow children to operate the controller.
Specifications
Input voltage:
Output voltage:
Maximum Current:
Fuse Size:
Control Action:
Control Mode
Output switching device:
100 to 240 VAC 50 /60 Hz
Same as the input.
15A at 120V, 10A at 240V
15A Fast blow.
Heating (reversed action) or cooling (direct action)
PID, PI, PD, P or On/off
Built-in optically isolated solid state relay with zero voltage
crossing switching.
Sensor type:
Pt100 RTD sensor
Sensor tip dimensions:
4 mm diameter x 50 mm long.
Sensor cable length,
3 ft (915 mm)
Alarm:
High limit alarm and Open loop alarm with LED and
buzzer.
Timer Range:
1 to 9999 minutes for each step. 6 steps total.
Temperature resolution:
0.1 °C or 0.1 °F
Temperature display range: -50.0 to 200.0 °C or -58.0 to 392.0 ° F
Temperature accuracy:
0.1°C or 0.2 °F for 0-85 °C (32.0 to 185.0 ° F)
Dimension:
6x3x7 inch (155 x80x180 mm) W x H x D.
Weight:
2.8 lb (1.3 kg)
Warranty:
1 year for controller and sensor
Operating Instructions
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1) Description of the controller.
Figure 1. Front Panel
(1) Parameter Window (LED) - For displaying temperature values and controller's
system parameters.
(2) Output status indicator - In normal mode, this LED indicates the heater status.
When it is on (lit), the heater is powered. When it is off, the heater power is off. When
it is flashing, it means the heater is on and off intermittently to reduce the power
output. It should be synchronized with the power light on the cooking device.
(3) SET Key - For showing current temperature settings, entering parameters setting
mode and confirming various actions taken.
(4) “+” Key - To increment displayed value.
(5) “-”Key - To decrement displayed value.
(6) Time Key - Change the Parameter Window between current timer and
temperature values, when pressed.
(7) Alarm indicator - Lit when the alarm is on.
(8) Timer status indicator - In normal mode, when “(8)” is on and “(9)” is flashing,
LED shows the time passed since it’s powered on.
(9) Mode indicator - the small “dot” is used to indicate what mode the controller is in.
 When it is flashing and “(8)” stays on, “(1)” is the time that has elapsed since
it’s powered on.
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When it is flashing “(8)” is off, the controller is in the parameter setting mode.
“(1)” is the value can be changed by using (4) and (5) key.
Figure 2. Back Panel
2) Connecting the controller
Figure 3. Typical connection between the controller and
the heating device (in this example, the cooker).
The connection of the controller should be done in the following steps.
 Plug the temperature sensor to the back of the controller.
 Plug the power cord to the power outlet on the wall.
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Turn on the controller to make sure the controller powers up properly, and the
temperature display is in the range expected. Then, turn off the controller.
 Plug the heater to the back of the controller. If the heater has a switch, put it in the
off position. Put the sensor inside the container to be controlled.
 Turn on the controller.
 Turn on the heating device.
Remark The connector of sensor contains a slot for correct pin connection. It also has a
spring lock to prevent disconnections from accidental pulling on the cable. The following
pictures show how to install and remove it.
Figure 4. How to install the sensor.
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Figure 5. How to remove the sensor.
3) Programming the temperature profile.
A total of 6 steps can be programmed with this controller. Each step contains the
temperature (C0X) and time duration (T0X) setting. They are represented by the symbol
C0X and T0X, where “X” is the step number (e.g. Step 4 temperature is represented by
C04 and step 4 time is represented by T04). The character, “T”, is displayed as the
symbol, “ ”. Time is defined as the duration between the last step and the next step.
Please make sure the time is long enough for the heater to heat up the oven. If the time
is set too short, the temperature may not be able to reach the current step temperature
setting, before it jumps to the next step. The time unit is in minutes with 1 minute
resolution. If the recipe only needs one step, you can program the time of the rest of the
steps to zero.
To program the temperature profile, press SET key once. The display will show C01 for
one second and then display the temperature setting for step 1. Use “+” and “-” keys to
change the temperature setting. When finished, press the SET again to confirm the
change. The display will show T01 for a second and then change to the cook time setting
for step 1. Use “+” and “-” keys to change the cook time setting. When finished, press the
SET again to confirm the change. The display will go the step 2 setting. The following is
the flow chart for the setting procedure.
6
SET
4 sec
SET
SET
SET
SET
SET
SET
SET
SET
SET
SET
SET
SET
SET
SET
Figure 6. Temperature profile programming flow chart.
The temperature setting will not be changed if SET is not pressed (confirmed). After
programming the necessary steps for cooking, you can finish programming by pressing
the SET continuously until it passed T06 and the LED displays the current temperature.
You can also leave the controller alone. The display will return to the normal display
mode if no key is pressed within 15 seconds.
The initial program setting for the controller is for one step heating. The temperature
profile is programmed to start at 150 °F for 600 minutes of heating.
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Table 1. Initial program setting
Step #
Temp (C)
Step #
Time (min)
C01
60.0
T01
600
C02
0
T02
0
C03
0
T03
0
C04
0
T04
0
C05
0
T05
0
C06
0
T06
0
4) Checking the current step and display the time
This is done by pressing the Time Key “(6)” once. The display will show T0X for one
second before it displays the time it has been on that step. e.g., it will display t03 for a
second, if the controller is in step 3 of the process. When “(8)” is on (lit) and “(9)” is
flashing at the same time, LED is in timer mode and shows the actual time passed since
the controller was in the current step. Please note that this is not the total time since the
controller is powered up. Pressing the Time key again will switch the display to the
current temperature. Both “(8)” and “(9)” will be off.
3.4 Tuning the controller
This controller is shipped with parameters set for commercial rice cookers. You can try to
use these settings for other cooking device also because they are suitable for a typical
slow response and balanced system. If you feel the performance is not ideal, you can try
to use the recommended PID parameters listed in Table 2. These are the parameters we
obtain from tuning the system manually. If your cooker is not listed in the Table 2 of our
pre-selected cookers, or the PID parameters we provided are not working for your liking,
you can use the auto-tuning function to let the controller to determine the PID
parameters automatically. You can also manually tune the PID parameter if you are
familiar with PID control technology. To activate the auto-tuning processes or change the
P, I and D parameters, please see the next section and Figure 8.
Table 2. Recommended PID parameters that can be used as reference point.
Symbol
P
I
d
Display
P
I
d
Commercial Rice cooker, steam table
180
700
40
Commercial Rice cooker, steam table
18
0
150
Home use rice cooker,
54
60
15
17
0
40
Home use rice cooker, wine fermentation. (PD
mode) Switch set at Warm position
8
Slow cooker, 7 quart
180
700
40
Slow cooker, 4 quart
54
60
15
Slow cooker, PD mode (low overshoot)
40
0
40
Bradley Smoker
70
600
150
Please note that the P value in table is in Fahrenheit unit. If the controller is using
Celsius unit, divide the P value by 1.8. If you switch from Fahrenheit display to
Celsius, the controller will automatically convert all the settings.
4) Controller System Configuration Parameter.
This section discusses how to configure the controller for a specific application. For most
sous vide cooking users, there is no need to read this section. The controller’s default
setting is for most common configurations of sous vide cooking.
The controller parameters are divided into two groups.
A) The first group of parameters is related to the control performance. They need to be
adjusted based on the system to be controlled. Table 3 shows the list of these
parameters, their range and initial set value.
Table 3. List of control parameters and its initial settings under code 166.
Symbol
P
I
d
AT
T
Display Description
Proportional band (in 0.1 Degree)
P
Integral constant (second)
I
Derivative constant (second)
d
AC Auto-tune
Cycle rate (second)
C
Range
0-600
0-900
0-300
0=off 1=on
1-100
Initial
180
700
40
0
2
Details about each parameter
 P. Proportional band. It is in 0.1 degree units. This parameter controls the output
of the controller based on the difference between the measured and set
temperature. Larger the P number means the weaker the action (lower gain). e.g.
If P=100, the proportional band is 10 degree (100 x 0.1=10). When the sensor
temperature is 10 degrees below the proportional band (10 degrees below the
setting), the controller will have 100% output. When the temperature is 5 degrees
below the set point, the output is 50%. When the temperature is equal to the
setting, the controller will have 0% output (assuming integral and derivative
functions are turned off). This constant also affects both integral and derivative
action. Smaller P values will make the both integral and derivative action stronger.
Please note the value of the P is temperature unit sensitive. If an optimized P
value was found when operating the controller in Celsius, it needs to be multiplied
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by 1.8 when changed to Fahrenheit.
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On/off mode. If P is set to 0, the control mode will be changed from PID mode to
On/off mode. On/off mode should be used for controlling an external relay, a
solenoid valve, or a compressor of freezer. You also need to set the hysteresis
band (dead band) for the on/off mode. In the on/off mode, Integral and Derivative
parameters are not valid.
I. Integral time. The unit is in seconds. This parameter controls the output of the
controller based on the difference between the measured and set temperature
integrated with time. Integral action is used to eliminate temperature offset. Larger
numbers mean slower action. e.g. assuming the difference between the
measured and set temperature is 2 degree and remain unchanged, the output will
increase continuously with time until it reaches 100%. When temperature
fluctuates regularly (system oscillating), increase the integral time. Decrease it if
the controller is taking too long to eliminate the temperature offset. When I=0, the
system becomes a PD controller. For very slow response systems such as those
with slow cookers and large commercial rice cookers, setting I = 0 will significantly
reduce the temperature overshoot.
d. Derivative time. The unit is in seconds. Derivative action contributes the output
power based on the rate of temperature change. Derivative action can be used to
minimize the temperature overshoot by responding to its rate of change. The
larger the number is, the faster the action will be. e.g. when the door of an oven is
opened, the temperature will drop at a very high rate. The derivative action
changes the controller output based on the rate of change rather than the net
amount of change. This will allow the controller to act sooner. It will turn the heater
to full power before the temperature drops too much
AT, Auto-tuning
Every type of cooker has its own unique set of tuning parameters. For the
controller to heat with stability, it should have programmed with the tuning
parameters for the cooker currently being used.
When Should the Controller be Tuned?
The Auto-tuning function (it’s often known as self-tuning) can automatically
optimize the PID parameters for your chosen cooking system. The auto-tuning
function will heat up your cooker then let it cool down. It will repeat this heat/cool
cycle several times. Based on the response time of the whole cooking system, the
controller will calculate and set the PID parameters for your cooker.
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Figure 7. Auto-Tuning
Before using the auto-tune function, you must set the cooking equipment up in the
exact configuration it will be used. For example, to tune a rice cooker, place the
sensor in the room temperature pot filled with water and plug the cooker into the
controller. If the cooker has its own thermostat or power control, turn both as high
as they’ll go. Set the controller to the appropriate power level (see next Section).
Turn the controller and cooker on, and then enter the desired set point
temperature close to your normal cooking temperature.
You should always write down your old PID parameters, before letting the
controller perform auto-tuning. This way if something goes wrong, you can always
go back to your old PID parameters. The water amount in the pot should be the
same volume as you would have normally used. Basically, you must setup your
cooking system close to your actual cooking environment.
The duration of auto-tuning depends on how fast the system is responding to the
heating and cooling cycle. If the temperature of the cooker takes a long time to
drop when the heater is off, the auto-tuning could be a very long tuning process.
This is especially true with a well insulated cooker. The auto-tuning should be able
to tune most of your chosen heaters/cookers/smokers with great results.
To activate auto-tuning, set A to 1; then, exit the menu (see Figure 8. Code 166
Parameter setup flow chart). The display will start to flash alternately between A
and the current water bath temperature, which indicates auto-tuning is in progress.
When the display stops flashing, the auto-tuning is finished. Now, the newly
calculated PID parameters are set and are used for the system. The new
parameters will store in the memory even when the controller is restarted
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T, cycle rate. The unit is in seconds. This unit determines how long for the
controller to calculate each action. e.g. If T is set to 10 seconds, when the
controller decides the output should be 10%, it will turn on the heater 1 second for
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every 10 seconds. This parameter should set at 2 second for heating with an
electric heater. When controlling a solenoid valve or a compressor of refrigerator,
the T should be set to 10-20 to reduce the frequency of on/off.
To prevent changing critical parameters by accident, an access lock, LCK is used.
Special code is needed to open the lock for these parameters.
This group of parameters can be accessed by input code 166. Figure 8 is the flow chart
that shows how they can be changed.
Figure 8. Code 166 Parameter setup flow chart
Press and hold SET key for 4 seconds until LED displays “LCK.” Then release the SET
key. The display will show “0”. To get into parameters setting mode, you need to key in
the pass code. Use “+” and “-” keys to adjust the display to 166 (which is the pass code)
and press SET. The LED will show “P” for a second and then its P setting value, Use “+”
and “-” keys to change the setting. When finished, press the SET again to confirm the
change. The display will show the “I” for a second and its I setting value next, use the
same “P” setting procedure to set the I value. When finished, press the SET again to
confirm the change. The display will show the “d” for a second and its value next. Use the
same “P” setting procedure to set the d value. When finished, press the SET again to
confirm the change. The next setting is A, the auto-tune. Use “+” to set the value to 1
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and press SET will activate the auto-tune. The next setting is the “t” setting, use “-” and
“+” to set the cycle time value. This value should remain 2 for most application. After
change the PID parameter, the controller needs to be turned off and on again for the best
result.
B) The second group is about the system configuration and set up. Once they are set,
they normally do not need to be changed. This group of parameters can be accessed by
input code 155. If you don’t want your system to be altered by other people, do not let
others know this code. Table 4 shows the list of the parameters, their range and initial set
value.
Table 4. List of control parameters and the initial settings under code 155
Symbol
SC
AL
FA
OAL
Hy
COOL
Out
C-F
Display Description
SC
AL
FA
OAL
HY
COOL
00t
C-F
Range
Initial
Off set (degree)
-20.0 ~+20.0
Alarm Setting
-58.0-392.0°F
-50.0-200.0°C
180.0
Alarm buzzer
0=off 1=on
0
Open loop alarm
0=off 1=on
0
Hysteresis band
0-100
0.3
0=heat 1=cool
0
1-100
100
°C or °F
°C
Control mode (heating or cooling)
Output power reduction (%)
Temperature unit
Details about each parameter.
 SC, calibration offset. The parameter is used to make the input offset to
compensate for the error produced by sensor. Each unit is 0.1 degree. e.g. if the
temperature displays 2.0 °C in ice water mixture, set SC=-2.0 will make the
display to shown 0.0 degree.
 AL, Alarm temperature in degree. When the temperature passes the alarm set
value, the alarm LED and buzzer will be turned on. When the temperature drops
to that value, the LED and buzzer will be turned off. The alarm is for high limit
alarm only. It will not shut off the out.
 FA. Alarm buzzer control. When FA=1, the buzzer will be on when the alarm
LED is lit. When the FA=0, the buzzer will not be turned on at the alarm
temperature.
 oAL. Open loop alarm. This parameter is for detecting an open loop in the control
system. e.g. if the sensor was forgotten to be inserted in the oven, or the sensor is
defective, or the heater is defective. When enabled (oAL=1), it will shut off the
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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.
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Figure 9. Code 155 Parameter setup flow chart
Press and hold SET key for 4 seconds until the Parameter Window displays “LCK”.
Release the SET. The display will show “0”. Use “+” and “-” keys to adjust the display to
155 (another pass code) and press SET.
Setting the calibration offset. The parameter window will first show “SC “for a second
and then its value, Use “+” and “-” keys to change the setting. When finished, press the
SET again to confirm the change. For example, if the temperature is 1 °C too high during
calibration then use “-” to set the value to -1 to offset value.
Setting the output reduction. The parameter window will first show “OUt “for a second
and then its value, Use “+” and “-“ keys to change OUt value to your desired limit value
and press SET.
Setting Celsius (C) or Fahrenheit (F). When SET is pressed, the display will show “CF” and then its value of either “C” or “F”. Press “-” for C or “+” for F.
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The setting for AL, FA, oAL, Hy, Cool and TK are similar as the rest of parameters.
Warranty
Auber Instruments warrants this controller to be free from defects in material and
workmanship for a period of one (1) year from the date of the original purchase when
utilized for normal use, subject to the following conditions, exclusions and exceptions.
If your appliance fails to operate properly while in use under normal conditions within the
warranty period, return the complete appliance and accessories to
Auber Instruments
5755 North Point Parkway, Suite 97
Alpharetta, GA 30022
If the appliance is found by Auber Instruments to be defective in material or workmanship,
Auber Instruments will repair or replace it free of charge. A dated proof of purchase may
be required.
The liability of Auber Instruments is limited solely to the cost of the repair or replacement
of the unit at our discretion. This warranty does not cover normal wear of parts and does
not apply to any unit that has been tampered with or used for commercial purposes. This
limited warranty does not cover damage caused by misuse, abuse, negligent handling or
damage due to faulty packaging or mishandling in transit. This warranty does not cover
damage or defects caused by or resulting from damages from shipping or repairs,
service or alterations to the product or any of its parts which have been performed by a
repairperson or facility not authorized by Auber Instruments.
This warranty is available to the original purchaser of the unit and excludes all other legal
and/or conventional warranties. The responsibility of Auber Instruments, if any, is limited
to the specific obligations expressly assumed by it under the terms of the limited warranty.
In no event is Auber Instruments liable for incidental or consequential damages of any
nature whatsoever. Some states/provinces do not permit the exclusion or limitation of
incidental or consequential damages and therefore the above may not apply to you.
This warranty gives you specific legal rights and you may also have other rights which
vary from state to state or province to province.
*Important: Carefully pack item(s) to avoid damage in shipping. Be sure to include proof
of purchase date and to attach tag to item before packing with your name, complete
address and phone number with a note giving purchase information, model number and
what you believe is the problem with item. We recommend you insure the package (as
damage in shipping is not covered by your warranty). Mark the outside of your package
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“ATTENTION CUSTOMER SERVICE”. We are constantly striving to improve our
products and therefore the specifications contained herein are subject to change without
notice.
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Appendix 1
Managing the heat generated by the controller
The heat dissipation of the controller is directly related to the electric current drawing
power of the heater. If your cooker consumes less than 10 ampere of current or your pot
is less than 5 gal (19 liters), you do not need to worry about the heat generated by the
controller.
Sometimes, the AC current requirement might not be marked on the cooking appliance.
To find out how much current it will draw, divide the power (in wattage) by the line voltage,
for example, an 1800 watts 120V heater will draw 15A. A 2000 watts 240V heater will
draw 8.3 Ampere.
Why the heat becomes an issue?
The solid state relay (SSR) used in the controller is a critical component for the precision
temperature control. With the SSR, the power can be switched at high speeds with no
noise and no life time limitation. Compared with electromechanical relays, however,
SSRs have one drawback. They generate heat when passing the current. SSR’s are
made of semiconductors that have a limited conductance. When passing current, the
heat will be produced from the resistance. Each ampere of current will produce about 1.3
watts of heat. When 12 Amp is passing through the controller, 16 watt of heat is
produced in the controller. As more heat is produced, the temperature inside the
controller will rise. If it reaches to higher than 70 °C, it can shorten the life or even
damage some other components in the controller. The temperature inside of the
controller depends on the amplitude of the current, how long the controller needs to run
at full power and the ambient temperature.
The heat is only an issue during the start of the heating when the heater is running at full
power. Once the temperature is close to the set point, the controller will probably need
less than 50% of the power to maintain the temperature. Since the heat is directly related
to the current passing the controller, the heat produced at steady state will be
insignificant and can be ignored.
When the heat becomes an issue?
This controller can run at 10A continuously without worry of the temperature of the
controller. At 12A, the temperature of the controller will increase with time. The bottom of
the controller where the heat sink is located can rise by 63 °F (35 °C) from ambient if
running at full power continuously for 90 minutes. For this reason we don’t recommend
running the controller at full power for more than 90 minutes. For 120 VAC, 15 A for 90
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minutes will provide enough energy to heat 10 gallons (38 liters) of water up by 108°F
(60 °C). If your have a pot that is bigger than 10 gallons and the heater is drawing 15 A,
and you need to raise the temperature by 108 °F, you better use one of the methods
mentioned below to reduce the heat in the controller. Otherwise, you might damage the
controller.
Please note that when the ambient temperature is hot, as it often is the case in some
commercial kitchens, the temperature of the controller will get hotter. This is because the
heat dissipation is mostly determined by the temperature gradient (the temperature
difference between the ambient and the controller) instead of absolute temperature of
the controller itself. If the controller reaches 50 °C when the ambient is at 20 °C, it will
reach 70 °C when the ambient is at 40 °C.
Solutions to reduce the heat stress on the controller.
1) Use hot water. If you fill the pot with hot water that has a temperature close to the set
temperature, the heat dissipation of the controller is not an issue. As we have mentioned,
once the temperature is close to the set point temperature, the controller starts to pulse
(PWM) the power. The effective current is much lower, making heat not an issue.
2) Limit maximum output power. If you set output reduction parameter to 80%, then, a
15A heater will become a 12A heater. It will take 25% longer time to heat up the pot, but
the controller will not over heat.
In addition to these solutions, following information will also help you to manage the heat.
Place the controller in the right place. The SSR of Auber WS series controller is mounted
in the bottom of chassis. The chassis is made of 3 mm thick aluminum for good heat
dissipation. Do not cover the controller with any insulation. If you are running at 15 A with
a large pot, placing the controller in a well ventilated area and tilting the instrument up
with its front legs will help remove the heat more efficiently. However, the tilted position
may result in water collected at the back frame. Although the controller is splash proof,
you should avoid water to be dripped on the controller when you open the lid of the
cooker.
Increase the P value. This can only provide limited help for reducing the heat. P is the
proportional band. P=200 means the proportional band is 20.0 degrees. When the
temperature is raised to less than 20 degree from the set point temperature, the
controller will start to reduce the power sooner. But if the integration time is set to very
short, the controller might start to run at full power again soon.
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