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21.6 Volt metric door safety device with PTC
21.6.1 General characteristics
An electromechanical device is used as the door safety interlock, having the following functions:
•
When powered, the volt metric device closes the main switch which powers certain electrical components
of the washing machine (only if the door is closed).
•
During operation, the cursor remains mechanically blocked, preventing the door from opening when the
appliance is running. Once the power supply is cut off, the door remains locked for 1-2 minutes to ensure
that the drum has stopped before opening it.
In the applications analysed to this point, the door safety device was positioned after the anti-noise filter.
Consequently, it powered all the electrical components of the appliance; in this platform, it only powered the
solenoid valves and the motor.
•
Operating principle
Once the wash programme is started by pressing the start/pause button, the bi-metal PTC (contact 1) is
powered by the triac on the circuit board (J5-3): after 2-4 seconds, the switch (3-2) powering the electrical
components of the washing machine is closed.
1. Main circuit board
2. Door safety device - Traditional
Technical Support - DMM
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599 75 58-67 Rev. 04
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