Operating Principle Of Flow Meter - Electrolux Washer Service Manual

10.8.2 Operating principle of flow meter

The main components of the flow sensor are:
1. Turbine (with magnet and
counterweight mounted on the
outside)
2. Reed switch (normally open)
3. Magnet
4. Counterweight
Water entering the solenoid valve rotates the turbine (1) and magnet (3), which passes in front of the reed
switch (2), thus closing it. As this contact opens and closes, it generates pulses at a frequency that is a
function of water flow.
The turbine completes 230 revolutions for each litre of water. The operating range of the flow sensor is 0.2-
10 bar.
Using the signal it receives, the microprocessor can calculate the number of litres of water passing through
the solenoid valve.
Mechanical jamming of solenoid valve
The solenoid valve may jam open without being actuated (which will cause flooding if the pressure switch
controlling the water level does not trip). If this occurs, the electronic control system (which continuously
monitors the flow sensor) will lock the door, start the drain pump and display an alarm.
Low water pressure
If the flow sensor does not generate a signal during water fill even though power is being applied to the
solenoid valve, the cause of this condition may be a closed water tap or clogged filter on the solenoid valve
(with consequent low water pressure). If this occurs, a warning will be displayed and the cycle will continue
for five minutes, after which time an alarm will be signalled.
The solenoid valve controlling residual condensed water operates during the drying phase on washer-
dryers. The alarm is deactivated because the amount of water fill is very small.
SOI/DT 2005-01 dmm
Contact closed
Signal 0
40/65
Contact open
Signal 1
599 36 82-56