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NN-G55 AR
DESCRIPTION OF OPERATING SEQUENCE
1. Variable power cooking control
The digital programmer circuit controls the ON-OFF time
of power relay B contacts in order to vary the output power
of the microwave oven from “Low” to “High” power. One
complete ON and OFF cycle of power relay B is 22
seconds. The relation between indications on the control
panel and the output of the microwave oven is as shown
in table.
NOTE: The ON/OFF time ratio does not correspond with
the percentage of microwave power since
approximately 2 seconds are required for heating of
magnetron filament.
2. Inverter Power Supply Circuit NEW H,V
This Inverter Power Supply Circuit supplies 4,000V DC to
the magnetron tube from the line voltage,220VAC 50Hz input.
functions as the H.V. transformer, the H.V.capacitor
and H.V.Diode.
1. The AC input voltage 220VAC 50Hz is rectified to DC
voltage immediately.
2. DC voltage will be supplied to the switching devices called
IGBT. These devices will be switched ON-OFF by the 20
to 40 kHz PWM. (pulse width modulation) signal from the
microcomputer in the DPC.
3. This drives the High voltage transformer to increase up to
2,000V AC and approximately 3V AC by means of
transformer.
4. Then the half-wave doubler voltage rectifier circuit,
consisting of the HV diodes and Capacitors, generates
the necessary 4,000V DC needed for the magnetron.
5. Output power of the magnetron tube is always monitored
by the signal output from the current transformer built into
the inverter ciruit.
6. Then this signal will be fed back to the microcomputer in
the DPC to determine operating conditions and output
necessary to control PWM signal to the inverter Power
Supply to control output power.
3. Inverter Turbo Defrost
When this Auto Control feature is selected and the Start
Pad is tapped:
(A) The digital programer circuit determines the power level
and cooking time to complete cooking and indicates
the operating state in the display window. Table shows
the corresponding cooking times for respective serving
by categories.
(B) When cooking time the display window has elapsed,
the oven tums off automatically by a control signal from
the digital programmer circuit.
4. Sensor Cooking
Auto sensor cooking is a revolutionary way to cook by
microwave without setting a power level or selecting a time.
All that is necessary is to select an Auto Sensor Program
before starting to cook.
Understanding Auto Sensor Cooking
As the food cooks, a certain amount of steam is produced.
If the food is covered, this steam builds up and eventually
escapes from the container. In Auto Sensor Cooking, a
carefully designed instrument, called the steam sensor
element, senses this escape of steam. Then, based upon
the Auto Sensor Program Selected, the unit will
automatically determine the correct power level and the
proper length of time it will take to cook the food.
HIGH
P10
100%
22
0
P9
90%
22
0
P8
80%
22
0
MEDIUM-HIGH
P7
70%
22
0
MEDIUM
P6
60%
22
0
P5
50%
22
0
P4
40%
22
0
MEDIUM-LOW
P3
30%
22
0
P2
20%
15
7
P1
10%
8
14
DEFROST
P3
30%
22
0
POWER SETTING
OUTPUT
POWER
(approx.)
ON-OFF TIME
OF POWER RELAY B (RY1)
ON (Sec.)
OFF (Sec.)
START
10 seconds
MAGNETRON
ON
T1
TIME
STOP
P1
POWER
P2
POWER
STEAM
DETECTED
Sensor Cooking Operation
(a) In the first 10 seconds there is no activity of micro waves.
T1 begins at the end of that 10 initials second.
(b). T1 is the time that the cooking begins to liberate steam.
(c). Then, the sensor measures the steam volume and the
microcontroller calculates the time and it determines the
potency for T2. T2 is displayed and the countdown begins.
T2
TIME
