Table of Contents
Advertisement
5.3
Door safety interlock (traditional version)
5.3.1
General characteristics
The electromechanical door safety device performs the following functions:
•
When powered, the voltmetric safety interlock closes the contacts of the
main switch that powers the electrical components of the appliance (only
if the door is closed).
•
During operation, the lever is blocked mechanically, preventing opening
of the door when the appliance is in operation.
•
When the power supply is disconnected, the door remains locked
for 1-2 minutes to ensure that the drum comes to a stop before
the door is opened.
•
The "door closed" pilot lamp may also be fitted using a support.
1. P.T.C.
2. Bi-metal strips
3. Contact in rest position
4. Contact closed
The PTC is a ceramic resistor whose internal resistance
increases with the temperature.
In this device, the PTC is used to heat the bi-metal
strips. The temperature deforms the two strips (from A
to B), thus moving the lever which closes the contact of
the main switch.
At the same time, the latch, which is actioned by the
contact plate, moves outwards to block the lever in
position. This procedure takes place within 5 seconds
after power is supplied.
When the power supply is disconnected, the PTC cools
(1 - 2 minutes), and the strips return to their original
position, thus opening the contact and releasing the
lever.
1. Latch
2. Lever
5.3.2
Electrical symbol
A
Common contact
B
PTC power supply contact
C
Main switch contact
5.3.3
Circuit diagrams
SOI/DT 2006-01 dmm
35/71
Connector
599 37 47-13
Advertisement
Table of Contents
