2.4.1DOOR INTERLOCK SWITCH
Drawing
There fixed hooks on the oven door, and opened two rectangle hole at the corresponding place at the right of the oven and the hook. Inside each rectangle hole, there fixed a micro switch. When the oven door closed, the two hook on it would insert into the rectangle hole, and just push down several micro switches. At that time, S1, S2 are closed, S3 is cut off, and the microwave oven is under preparation of working.
fuse | main latch switch |
S1
L
Epilot switch S3
N
| S2 |
door closed | assistant latch switch |
To that mechanical control microwave oven, no sooner you turn the time switch to set the heating time than the
power would be supplied to the back to start the oven. To those touch control microwave oven, hardly do you set the heating time and power, and touch the start button when the power would supplied to the back to start the oven.
When pressing down the door release button or pulling the door handle to open the door, the safety interlock switches S1, S2 are cut off, and the monitor switch S3 is closed, and the microwave oven would stop operating immediately. Provided due to some man - made or the appliance itself reasons, when the door is open, and the safety interlock switches S1, S2 are not automatically cut off, due to the existence of the
monitor switch (S3) which is still at conducted condition, the monitor switch would immediately make the 120V voltage
From this we can understand the function of the interlock switch is when the door is unclosed, the oven wouldn’t work, when the door is opened when the oven is working, it would stop the working immediately
(a)
Fig.2-5
tch holder
itch
door hook
witch
door hook
door release button
latch switch holder
latch switch
pilot switch
screw
latch switch
pilot switch
screw
2.4.2TIME AND POWER DISTRIBUTOR
Time and power distributor is mainly composed of timer motor and two
sets of gear switch S4 and S5. When the timer is at zero position, the gear switches are cut off, when the heating time is settled, the gear switch is closed. When started
the oven, the time | motor starts | working. | When it |
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reaches the | settled | time, it would cut off | the gear |
| timer & power motor | ||||
switch (s4) to step the oven working. The gear switch |
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(S5) is designed for controlling the output of the |
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microwave oven, actually for controlling the output of | 120V |
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the magnetron. It mainly by the method which make |
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the magnetron working internally at the same working |
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point | to change | the | output of the magnetron. This | S 4 | S 5 | ||||
method was called “CONDUCTION RATIO CONTROL”. |
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But | there | is | another method | which | is | called |
| Fig . 2 - 6 | |
“ELECTRIC | LEVEL | CONTROL” | which is | through |
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changing the working point (such as anode voltage or magnetic field) to change the output of the magnetron. Because of conduction ratio control method is low cost, high function and high reliability, it is widely used for
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