Contact / Moisture Sensor; General Characteristics - Electrolux EFME617SIW Service Manual

Electrical Components (For Models 617, 517 and 417 Series)
Function of Hi-Limit Thermostats
Based on the vast amount of heat produced
by clothes Dryers during the course of normal
operation, it is important that a secondary safety
option is available in case problems arise. A Hi-
Limit Thermostat serves as a safety feature that
keeps the Dryer from becoming hotter than a
certain temperature. Once the temperature reaches
at a certain point within the Dryer, the circuit that
provides power to the heater will open. This allows
the Hi-Limit Thermostat to act as a secondary safety
option for the primary thermostat, and also for other
components such as the Thermistor and Blower.
Hi-Limit Thermostats During Normal Operation
The standard position of the Hi-Limit Thermostat is
closed, allowing current to flow to the heater without
interruption. Under normal conditions, the Dryer's
primary operating thermostat will cycle the heater
ON and OFF to prevent temperatures from rising too
high within the Dryer. The Hi-Limit Thermostat will
remain unaffected through all of these cycles, since
the temperature inside of the Dryer will stay lower
than what is required to activate the Hi-Limit Sensors
(generally 250-degrees Fahrenheit, though the exact
temperature may vary).
Conditions to Activate Hi-Limit Thermostats
If the temperature within the Dryer exceeds the
temperature allowed by the Hi-Limit Thermostat,
the unit will activate and turn OFF the power to the
Dryer's heater. There are several conditions that could
lead to this increased temperature, including a fault
in a part such as the Primary Operating Thermostat,
Thermistor, and Blower. Other conditions that can
lead to an increase in temperature are significant
enough to trip the Hi-Limit Thermostat, include the
improper configuration of components, such as the
Primary Thermostat or heater. Blocked or clogged
exhaust vents can also cause a significant increase in
the temperature within the Dryer and are one of the
most common causes for the activation of a Hi-Limit
Thermostat.
Component Specifications
S.No. Component
High-Limit
1
Thermostat

7.10 Contact / Moisture Sensor

WARNING
When replacing the Contact / Moisture Sensor,
refer to the code shown in the list of spare parts
related to the Appliance.

7.10.1 General Characteristics

A "Moisture Sensor" or "Dryness Control" retards
the advancing of the
timer. The device uses an
Electronic Control Board
in conjunction with sensor
strips inside the drum, which
come into contact with the
clothing as it tumbles. When
contact is established with
the wet clothing, a short is created between the two
strips allowing power to flow to the Electronic Control
Board which then acts upon the information allowing
the timer to advance or stop.
The Moisture Sensor controls may count the number
of times this short occurs over a given period and
act upon that information appropriately. More 'hits'
means more wet clothing in the Dryer, in which case
the control may delay advancing of the timer for
longer, to allow more time for them to dry. In this case,
less 'hits' would mean fewer or not as damp clothing
in the Dryer, which means advancing of the timer may
not be retarded as long.
24
Specification
240 V, 25 Amp Resistance
For Electrical model:
Opening Temp: 260 ± 8 ºF,
Closing Temp: 190 ± 11 ºF,
Max. Temperature: 350 ºF
For Gas model: Opening
Temp: 200 ± 6 ºF, Closing
Temp: 130 ± 7 ºF, Maximum
Temperature: 350 ºF.