The school is located in Caochang Street, Chengguan District, Lanzhou City, Gansu Province, covering an area of 42 mu, with fixed assets of more than 50 million yuan and a construction area of 62,369 square meters. Teaching and training facilities are complete, including a teaching administrative complex building, an experimental building, a practice building and a training complex building; Respectively a substation simulation station and a simulation power station; Equipped with boiler, steam turbine, thermal self-heating, fluid mechanics, relay protection, instrumentation, electronics, high voltage, motor, thermal engineering, material mechanics, elevator maintenance, home appliance maintenance, etc. 14 laboratory and a model room; There are practice sites for thermal engineering, electrical engineering, fitter and welding; Equipped with advanced voice classrooms and electronic reading rooms; Each classroom is equipped with bidirectional controllable audio-visual equipment; There are libraries, sports centers, student apartments, student dormitories, student canteens and so on.
(1) What are the grades of vocational qualification certificates?
* * * is divided into five grades, and some occupations are set to four grade