6
R-7H55
SENSOR COOKING CONDITION
Using the SENSOR REHEAT, SENSOR RICE COOK or
SENSOR STEAM MENU function, the foods are cooked or
defrosted without figuring time, power level or quantity.
When the oven senses enough steam from the food, it
relays the information to its microprocessor which will calcu-
late the remaining cooking time and power level needed for
best results.
When the food is cooked, water vapor is developed. The
sensor "senses" the vapor and its resistance increases
gradually. When the resistance reaches the value set ac-
cording to the menu, supplementary cooking is started.
The time of supplementary cooking is determined by experi-
ment with each food category and inputted into the LSI.
An example of how sensor works: (BAKED POTATOES)
The shut-off relays and cook relay are de-energized and
the power transformer, oven lamp, etc. are turned off.
6. Opening the door or touching the STOP/CLEAR pad, the
time of day will reappear on the display and the oven will
revert to an OFF condition.
FIRE SENSING FEATURE (MICROWAVE MODE)
This model incorporates a sensing feature which will stop
the oven's operation if there is a fire in the oven cavity during
microwave cooking.
This accomplished by the LSI repeatedly measures the
voltage across the temperature measurement circuit (ther-
mistor) during it's 32-seconds time base comparing the
obtained voltage measurements. If the most recent voltage
measured is 300mV grater than the previous voltage meas-
ured, the LSI judges it as a fire in the oven cavity and
switches off the relays to the power transformer, fan motor
and convection motor. The LSI also stops counting down
and closes the damper door so that no fresh air will enter the
oven cavity. Please refer to the following section for a more
detailed description.
Operation
Please refer to the timing diagrams below.
1. The thermistor operates within a 32-seconds time base
and it is energized for three (3) seconds and off for 29
seconds. Two (2) seconds after the thermistor is ener-
gized, the voltage across the temperature measurement
circuit is sampled by the LSI and twenty one (21) sec-
onds after the thermistor is cut off the LSI turns on the
cooling fan for six (6) seconds.
2. The above procedure is repeated. If the difference
between the first voltage measured (in step 1) and the
voltage measured when the procedure is repeated (step
2) is greater than 300mV the LSI makes the judgment
that there is a fire in the oven cavity and will switch off the
relays to the power transformer, fan motor and convec-
tion motor. The LSI also stops counting down and closes
the damper door so that no fresh air will enter the oven
cavity.
3. Once the fire sensor feature has shut the unit down, the
programmed cooking cycle may be resumed by press-
ing the "START" pad or the unit may be reset by pressing
the "CLEAR" pad.
CONVECTION
MOTOR
THERMISTOR
Sensing
Voltage
ON
OFF
ON
OFF
ON
OFF
0 2
24
30
64 (sec.)
3 sec.
Sensing the voltage across the temperature measurement circuit.
6 sec.
3
32 (sec.)
IMPORTANT:
During sensor cooking operation, the fire sensing op-
eration sequence will not begin until the AH sensor has
detected vapours and initiated a sensor cooking cycle.
This is because the operation of the convection fan
would interfere with the AH sensor's vapour detection.
MICROWAVE
MICROWAVE
AH SENSOR
1. Potatoes at room tempera-
ture. Vapor is emitted very
slowly.
2. Heat potatoes. Moisture
and humidity is emitted rap-
idly. You can smell the
aroma as it cooks.
3. Sensor detects moisture
and humidity and calcu-
lates cooking time and vari-
able power.
Cooking Sequence.
1. Touch SENSOR REHEAT, SENSOR RICE COOK or
SENSOR STEAM MENU pad.
NOTE:The oven should not be operated on SENSOR
REHEAT, SENSOR RICE COOK or SENSOR
STEAM MENU immediately after plugging in the
unit. Wait five minutes before cooking on SENSOR
REHEAT, SENSOR RICE COOK or SENSOR
STEAM MENU.
2. The coils of shut-off relays (RY-1 and RY-4) are ener-
gized, the turntable motor, oven lamp and cooling fan
motor are turned on, but the power transformer is not
turned on.
3. After about 16 seconds, the cook relay (RY-2) is ener-
gized. The power transformer is turned on, microwave
energy is produced and first stage is started.
The 16 seconds is the cooling time required to remove
any vapor from the oven cavity and sensor.
NOTE: During this first stage, do not open the door or touch
STOP/CLEAR pad.
4. When the sensor detects the vapor emitted from the
food, the display switches over to the remaining cooking
time and the timer counts down to zero.
At this time, the door may be opened to stir food, turn it
or season, etc.
5. When the timer reaches zero, an audible signal sounds.
