1. Check the environmental conditions. The interior and environmental temperature, humidity, cleanliness of the electronic equipment room and engineer room are proper and the lighting of the central control room is enough, the conditions for the operators to monitor are available. 

2. Visual inspection. Check the system equipment to confirm that it has good apperance, has not lost or lacked any parts, it doesn't rust and deform and has not obvious damage. The power supply fuse with power supply circuit and conduit fuse of module shall be in accordance with the requirement of equipmen usedt; the system equipment shall be neat, all kinds of logo shall be complete, clear and explicit. 

3. The system cannot be cleaned only after the power for the system or equipment is in outage. 

4.As for the requirement that should be anti-static, during maintenance, anti-static work must be well done. The workers must wear anti-static wrist strap and shall not touch the electric circuit part as possible; the quipment shall be put on anti-static plate, the purging equipment shall be ground in order to prevent electrostatic discharging from damaging the equipment. 

5.The power of cleaner for cleaning must be enough, so as to timely suck up the dust raising. The equipment must be cleaned with special cleaning agents. The clean instrument air is used for purging. It is forbiden to use metal pipe in front of the air pipe. The brush shall be discharged towards ground. The dust purged shall be cleaned by the cleaner in order to aviod corrosion to the circuit board and to prevent static electricity occurring.

 6. Check the inside and outside components of the equipment to confirm they are installed firmly and not loosen, the screws installed shall be complete. The cable laying and strapping shall be tidy and beautiful, the marks shall be complete and clear. 

7. Treatment of power line and components . The power circuit components shall be cleaned according to the methods for cleaning and purging the module. After they are assembled, they shall be tested for performance. 

8. If the device is provided with a cooling fan, be sure to check whether the cooling fan is working normally or not, and to clean , purge or replace the cooling fan, in case of that during operation of DCS, due to failure of cooling fan, the cabinet has excessive high temperature and cause failure of modules. 

9. Inspection of circuit