Simple improvements to circuitry prevents forced switching of the operation mode after a power failure

Circuit designs that can only switch modes when powered up create a risk of injury and death

Are you aware a power failure that occurs when elevator manufacturer maintenance personnel are carrying out inspection work can increase the risk of injury or death?
Conventional elevators utilize mode control technology so that the system can be switched to inspection mode only when the circuitry is powered up. Therefore, if a power failure occurs during inspection mode, the circuitry will be powered off and it will automatically return to the normal operation mode. If the maintenance personnel do not notice this and someone presses the lift button after the power is restored, it may result in injury or death. In order to avoid such risks, it is necessary to implement safety measures outlined in the new European elevator standards "EN81-20/21. From now on, similar standardization efforts are expected to also be implemented in Japan and China.

Using keep relays to build simple and safe electrical systems