Ntc-Sensor; Conductimetric Sensor - Electrolux EDR 2000 Service Manual

5.8 NTC sensor
The NTC sensor is fitted to the hot air fan duct. This sensor
consists of a resistor contained in a metallic capsule. Its
resistance decreases as the temperature increases.
The electronic circuit reads the resistance (which varies with the
temperature inside the dryer); when this resistance falls below a
certain value, the heater unit is switched off. As the air cools, the
resistance increases; when it reaches a given value, the electronic
circuit re-connects the heater unit to the power supply. This occurs
each time the temperature inside the dryer exceeds a given value,
which varies according to the drying cycle that has been selected.
5.9 Conductivity sensor
The conductivity sensor used in these appliances comprises an electronic circuit (within the main electronic system) and
an arrangement which detects the level of washing moisture.
The impedancy value is measured from the drum (1) itself to the insulated drum ribs (2). This impedance value is influenced
by the amount of washing in the drawing, the type of textile and the moisture level.
The brush (3) has contact with the drum ribs.
Via an insulated abrasive belt (4) on the
drum, it makes contact with the drum which
passes through the drum panel and which
has contact with the drum ribs by means of
clamps (5).
The carbon brush (6) which makes contact
with the drum shaft is situated in the protective
housing (7) of the drum shaft. This sensor is
connected to the electronic circuit via the
appliance housing, this representing the
earth of the electronic appliance circuit. The
empty drum is subjected to an infinite
impedance to the insulated drum ribs. This
changes if moist washing between the drum
and the drum ribs offers a measurable
impedance.
The impedance value amounts to
approximately 1 M - 25M and is converted in
an oscillation of between ~ 260Hz - OHz,
these being read and evaluated by the
electronic circuit (Fuzzy Logic), this
determining the duration and ultimate level
of the washing moisture in accordance with
the selected program.
06.2005 R.Kurzke
6
7
5
5
The new
carbon brush,
separately (left)
- 13 -
1 - NTC resistor
2 - Metallic capsule
3 - Terminals
4 - Plastic casing
4
2
2
and installed
(right).
1
3
599 522 797 EN