arcelik BEKO RETRO, Service Manual

Page: 46 / 98

RETRO WASHING MACHINE
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9.4. Water Level Sensor
An analog water level sensor which is fed by 5V power is used. This sensor ensures that the water
level is determined instantly with the frequency values it generates against the pressure created.
There are frequency values corresponding to these pressure values. An infinite number of levels
can be determined in the analog water level sensor. Water levels may vary depending on the
selected program, temperature and the auxiliary functions and the wash criteria of the designed
program.
Analog water level sensors are pressure-displacement converter elements in the broadest sense.
Analog water level sensors generate frequency modulation as output.
They are basically composed of 2 capacitors, 1 coil and a converter circuit located on the sensor
itself or on the control system it is connected to.
Pressure increment pushes a ferrite piece in the sensor to the inside of the coil. Therefore L
(inductance) value of the coil winding changes and the output value of the sensor – converter
circuit system changes. Therefore the pressure can be measured in an analog way.
The task of the water level sensor is to perform the basic controls such as deciding to take water
again, controlling the safety level. Moreover, if there is an error with the connections, water is
taken with the water level sensor.
9.5. Safety Switch
Safety switch is use for detecting door status while machine running and using for detecting
unbalance while spin phase.
The mechanical structure including two pins, these two pins should be conductive while door
closed and they should be open while door open.
Those two pins can be opened while door closed from press the arm, it’s use for detect the
unbalance from the opening time during the tub heating the safety switch.
Cable input : 5VDC / Data / GND.
Operating Voltage : 5VDC
25.5+0. 3/-0.0 KHz should be read from the Data and
GND terminals as a frequency when it is idle.
Picture 9.4 Water Level Sensor
Cable input : 5VDC / Data / GND.
Operating Voltage : 5VDC
25.5+0. 3/-0.0 KHz should be read from the Data and
GND terminals as a frequency when it is idle.
Picture 9.5 Safety Switch