To describe the design plan of hardware of PLC simulating experiment system which includes purify electrical source,carrier wave signal source,noise signal source,load network combined with the transmit character of PLC,and presenting hardware circuit diagram of each parts.

This paper discusses the existent interference problem from power supply wires in computer control sys-tem,introduces several effective methods against power supply interference,and invents a new AC clean power supply.

Reforming of Pollutant discharge (control) system of compressed air cleaning and drying unit for locomotive brake;