Abstract: In the power system, a large number of power equipment cabinets are used. During each maintenance work, warning signs for "working here" are hung on the corresponding cabinets, and warning signs for "operating equipment" are hung on adjacent switchgear or relay protection screens of the maintenance equipment. After the maintenance work is completed, the previously hung warning signs for "working here" and "operating equipment" need to be retrieved, which requires a relatively large workload. To solve this problem, this article developed an automatic conversion warning sign for photovoltaic power equipment cabinets. When the cabinet door is closed, it automatically displays "running equipment"; When the screen cabinet door is opened, it automatically displays "Work Here", saving manpower on hanging warning signs for "Work Here" and "Run Equipment". The warning signs also display that the required electricity comes from solar energy converted from photovoltaic arrays, which is energy-saving and environmentally friendly.