Sanyo SM-GA0005 Door Interlock Switch, Time and Power Distributor, Electric Level Control

Fig.2-5（b）

2.4.1DOOR INTERLOCK SWITCH

Drawing 2-5(a) is the circuit and construction diagram of the door interlock switch of a microwave oven. It mainly consists of interlock switches (S1, S2), and monitor switch (S3), door hook and starting mechanism of the door interlock switch.

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 short-circuited and blow up the fuse, and will never let the microwave oven working when the door is open.

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 (FIG.2-5b).

(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			t r a n s f o r m e r
reaches the		settled		time, it would cut off		the gear			timer & power motor
switch (s4) to step the oven working. The gear switch
(S5) is designed for controlling the output of the
microwave oven, actually for controlling the output of								120V
the magnetron. It mainly by the method which make
the magnetron working internally at the same working
point	to change		the	output of the magnetron. This				S 4	S 5
method was called “CONDUCTION RATIO CONTROL”.
But	there	is	another method		which	is	called		Fig . 2 - 6
“ELECTRIC		LEVEL		CONTROL”	which is		through

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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