Most washing machines have a timer that prevents you from opening the hatch just after the washing cycle ends. Instad you must wait for the timer to go off, usually a minute or two, before you can open the hatch.
Why? Would letting the user open the hatch immediately after washing ends pose any safety or other issues?
It’s not a component aware system. The last phase is generally the spin cycle. The controller knows to trigger the spin cycle, it knows to stop the spin cycle after a period of time. What it doesn’t know is whether those things actually happened. Particularly, it doesn’t know that the drum has actually stopped spinning. So, it just wait a predetermined amount of time before unlocking the door.
In the case of my own device the door actuator uses a wax motor. Put simply, current is changed to heat which melts the wax, pushing a pin the locks the door. To open the door, current is removed, the wax cools, hardens and shrinks and the pin slides back. Now the door can open. So, even if I remove power during a cycle the door will eventually unlock as the wax cools.
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It checks if the water is really truly out so opening the hatch is safe (as in no water coming out causing water damage). And for that it waits a time so the water has time to gather in the bottom.
Well, imagine someone opening the door if the water hasn’t fully drained out and the ensuing mess. If you’re wondering if someone is stupid enough to do that, then the answer is unequivocally yes. There is a reason the door locks for that amount of time - so somebody doesn’t brain fart, open the door, and flood the laundry room.
I have been saved by that washing machine lock on a number of occasions
So why not make the washing cycle end when the water has fully drained? I get the impression the timer starts after the drain.