Why does the room card run out of power?

As soon as the room card is pumped out, there is no electricity because the room card is also a power switch, and the room card can only be powered on if it is plugged in.

When the room card is taken out, the power supply will be cut off to prevent waste caused by the electrical appliances being kept on when no one is around. In addition, the room card is placed at the door to prevent the door card from being lost when checking in and leaving. Now the design of the hotel is to plug in the door card before it can be officially powered on. This is an advanced design concept, so the electricity needs to be plugged in all the time.