Description Of Operating Sequence - Panasonic NN-K593MF Service Manual

3 DESCRIPTION OF OPERATING SEQUENCE

3.1. Variable power cooking
control
High Voltage Inverter Power supply (U) controls output power
by the signal from Digital Programmer Circuit (DPC). Power
relay stays ON for P3 to P10 and For P1 to P2, both inverter
drive signal and power relay to control output power.
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.
Variable Power Cooking
POWER SETTING OUTPUT
POWER(%)
APPROX.
HIGH P10
P9
P8
MEDIUM-HIGH P7
MEDIUM P6
P5
P4
MEDIUM-LOW P3
P2
LOW P1
DEFROST P3
3.2. Inverter power supply circuit
NEW H.V.
This Inverter Power Supply Circuit supplies 4,000V DC to the
magnetron tube from the line voltage, 220-240V 50Hz/60Hz AC
input. functions as the H.V. transformer, the H.V.capacitor and
H.V.diode.
1. The AC input voltage 220-240V 50Hz/60Hz 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 H.V. 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 circuit.
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.
ON-OFF TIME OF
POWER RELAY (RY1)
ON(SEC) OFF(SEC)
100% 22 0
90% 22 0
80% 22 0
70% 22 0
60% 22 0
50% 22 0
40% 22 0
30% 22 0
20% 15 7
10% 8 14
30% 22 0
3.3. Inverter turbo defrost
When this Auto Control feature is selected and the Start Pad is
tapped:
1. 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.
2. When cooking time the display window has elapsed, the
oven turns off automatically by a control signal from the
digital programmer circuit.
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NN-S453WF