The Wastewater Treatment Plant in Harbin, China, is a large, state-owned enterprise that plays an important role in the environmental wastewater treatment for that region. The plant incorporates some of the most modern automation methods, and is designed to be environmentally friendly. One of the major concerns of plant managers is to improve and protect Harbin's fresh water supply.

Wenchang District's wastewater treatment plant covers a very large area. To get an idea of just how expansive the plant is, note that it has several pumping stations located outside the plant, as well as a large number of facilities inside the plant. The indoor facilities house PLCs, intelligent equipment, PH meters, computers, and servers, and include offices, mechanical bar screens, and clarifiers. With such a large variety of devices and equipment operating at the same time, it is crucial to deploy networking devices that are capable of integrating all devices into a single network that is fast, stable, resistant to failure, and highly automated.

System Description

The Yongda automation company applied Moxa's industrial Ethernet switches as their networking device of choice. One of the major reasons for choosing Moxa's switches is that they meet the wastewater treatment plant's stringent requirements for reliable and long-term operation. Networking devices used in this type of plant must be able to connect all stations within the plant's 2.7 km perimeter, and must provide reliable and fast data transmission. Moxa's ED6008-MM-SC satisfies all of the wastewater treatment plant's technical specifications, and its unique redundant ring feature even exceeds the recovery speed required by the plant.

For the case discussed here, PLCs were used as the control devices. The PLCs were set up at 10 different stations to collect information such as water level, pH factor, and water temperature. The collected data is then transmitted over the industrial Ethernet network to the central control room for processing and integrated analysis.

The Ethernet network formed by the ED6008-MM-SC multi-mode fiber optic switch uses the powerful Moxa Turbo Ring function to establish a redundant ring on the network. The Moxa Turbo Ring features a fast recovery time of under 300 ms when the network fails. The convenient management functions are also a major benefit for applications in water treatment plants. Functions include automatic network exception warnings for remote trouble shooting, and SNMP OPC Server Pro for easy integration with other devices.

Reliability and MTBF are major concerns for products used to create highly automated systems, and the ED6008-MM-SC switches have several features that answer these concerns—reliability, industrial strength, fan-less design, redundant DC power inputs, and high MTBF ratings all help ensure the reliability of network devices, and guarantee the long-term operation of the system.