Building a Robust Industrial Ethernet Network In Water and Wastewater Treatment Plants (WWTP)

May 14, 2014
The control and management of a Water and Wastewater Treatment Plant (WWTP) is a complex task that requires constant supervision.
The control and management of a Water and Wastewater Treatment Plant (WWTP) is a complex task that requires constant supervision. The typical geography of a WWTP covering hundreds of acres is not uncommon making networking these plants a large and robust task. And, as networking becomes more common, many older plants and remote stations which previously had no network are implementing SCADA systems linked with Ethernet.
A reliable Ethernet Network within Water and Wastewater Treatment Facilities is required, in order to:
  • Obtain precise control – any data error may result in the release of pollutants into the environment.
  • Flexibility on the connectivity for a typical SCADA (Supervisory Control and Data Acquisition) system linked with a Master Terminal Unit (MTU), and Remote Terminal Units (RTU); in order to perform remote data collection, and control devices, such as control pumps, gates, aerators, flow meters/sensors for the process.
  • Increase remote monitoring performance with Human Machine Interface (HMI) from remote stations.
There are several major features of the Industrial Ethernet Switch that would benefit WWTP Management:
  • Ethernet Network Redundancy
  • Flexible Fiber connectivity
  • Increased Determinism
  • Network Management
  • Advanced Event Handling
  • High Reliabilities
  • Cost Effective
Ethernet Network Redundancy
Having a redundant Ethernet network is extremely important to WWTP management. Many WWTP networks are still legacy, either built with stand-alone stations or have traditional Star Topology Ethernet Networks. Without network redundancy valuable data from field devices will be dropped if any stations encounter a defective device, severed link, or any other issue that may arise.
A Ring Topology Redundancy Ethernet Network contains a “Self-Healing” function that features the ability to re-build the network and re-route data immediately using a backup path. Most typical Ethernet Switches built with the traditional STP/RSTP network recovery protocol have a limitation downtime of about 2~3 seconds; which means there’s a risk that some data will be dropped within this period.
To prevent downtime, a firmware configuration called “Redundancy Network” can be used in popular Industrial Managed Switches such as the Antaira LNX-802 Series.
The built-in User-Friendly web console allows the user to easily configure the Redundancy Network by clicking the “Drop-down” menu and choosing the standard STP/RSTP or Antaira Ring network recovery protocol setup. The user can also assign any uplink ports from switch to switch to form a Ring Topology Network.
Benefits: Configuration of the redundancy network with Antaira’s proprietary fast network recovery protocol allows WWTPs to build a Robust Network and achieve a Self-Healing Network <20ms (up to 250 Switches) in order to prevent any network downtime or accidental shutdown.
The below figures demonstrate a Star vs. Ring Network Topology:
Flexible Fiber connectivity
Wastewater Treatment Plant Network coverage can span for miles and miles, therefore, fiber optics are the best choice to extend long distance connections from station to station.
The standard Ethernet cable has a limited cable uplink distance of <100Meters (326ft), but a Fiber Optics cable can have distance implemented up to 2Km with Multi-Mode Fiber, or from 15Km up to 120Km with Single-Mode Fiber.
Bandwidth with Fiber Optics:
  • In the past, the Wastewater Treatment Plant network design for field sites or pump stations consisted of a 100Fx fiber uplink network for low data rate transmission measurement equipment, such as Flow Meters, Sensors, Valves, etc.
  • Today, the implementation of a wider bandwidth network is a trend, due to requirements for networking of multiple field sites or station devices, in order to allow the SCADA system from an Administration Control center to execute remote status monitoring and control of devices such as, Radio Modem, HMIs, PLCs, VoIP, Surveillance Cameras, etc.
Benefits of Fiber Optics:
  • Expand distance between Administration Center and Stations
  • Prevent Electrical Noise Interference
  • Save on fiber cabling by building a Fiber Ethernet Ring Topology
Antaira Industrial Managed Switches provide wide range options of 10/100/1000Tx Ethernet in RJ45, and 100Fx or 1000SX/LX Fiber Connection models in SC, ST, and LC connector interface options. All models are ruggedly designed for operating in wide Ambient Weather and Temperature ranges:
  • Standard version: 0 to 60°C
  • Extended Temperature version: - 40 to 75°C
Increase Determinism
Within WWTP facilities, measurement devices, control or communication equipment, is required to report real-time data to the SCADA system; but other equipment, such as VoIP, or Surveillance Cameras, do not require this.
To build a reliable Ethernet Network within the WWTP, a Redundancy Network Feature is not the only consideration. Increased Determinism is also important within the Network, in order to perform real-time data transmission.
An Industrial Managed Switch with built-in Network Management Software is required, in order to increase determinism for all field equipment data transmission.
VLAN 802.1Q
A Virtual LAN (VLAN) is a logical network grouping that limits the broadcast domain, which allows a user to isolate network traffic, so only the members of the same VLAN will receive traffic from similar VLANs.
Allows user to segment the entire control network into different groups of substation equipment and transmit data to the same VLAN ID group.
  • Effective Traffic Control
  • Enhanced Network Security
  • Simple Network Management
IGMP Snooping
The Internet Group Management Protocol (IGMP) is an internal protocol of the Internet Protocol (IP) suite. IP manages multicast traffic by using switches, routers, and hosts that support IGMP. Enabling IGMP allows ports to detect IGMP queries, report packets, and manage IP multicast traffic through the switch.
Allows users the ability to direct multicast traffic equipment data (e.g. PLCs, Video) to travel to those end destinations that require that specific kind of traffic.
  • To prevent hosts on a local network from receiving traffic for a multicast group they have not explicitly joined.
  • Improve Performance and Real Time responsiveness
  • Saves Bandwidth
QoS (Quality of Service)
The QoS function can be configured using the 8,4,2,1 weight fair queue scheme to process priority queue from Highest to lowest. While the system is processing, 1 frame of the lowest queue, 2 frames of the low queue, 4 frames of the middle queue, and 8 frames of the high queue will be processed at the same time in accordance with the 8,4,2,1 policy rule.
This process allows the user to prioritize Traffic from higher priority control devices, such as I/O, drives or PLCs, in order to perform real-time control. Devices that are not time-critical, such as operator displays, HMIs and supervisory PCs, are assigned low priorities. If communication traffic is high, the switch processes the high priority messages before the low priority messages.
  • Ensures Important Data is delivered consistently and predictably.
Network Management
Web based management console User Friendly setup/configuration Network Online Monitoring
  • Allows Field Engineers to remotely access the switches monitoring their connectivity status.
Advanced Event Handling
System Event Log
Users can set up the mail server IP, mail account, password, and forwarded email account for receiving an event alert:
  • Enable Syslog/SMTP within Switches’ web console, the event log will be sent to system log server/SMTP server.
  • Also, per port log (link up, link down, and both) events can be sent to the system log server/SMTP server with the respective checkbox ticked.

System event type selection:

  • Device cold start,
  • Device warm start,
  • Authentication Failure
  • Network topology change
Port event type selection:
  • Link UP,
  • Link Down, and
  • Link UP & Link Down.
  • Power 1 or 2 Fail
  • Ability for Field Engineers to receive event alerts through email at anytime
  • Ability to log-in to the switches to check the status remotely
  • Ability to arrange schedule for immediate or future maintenance/repair
High Reliabilities
Most applications and equipment within WWTP facilities are found in an outdoor environment, so the ambient weather will affect the life cycle of any equipment in these field sites. Even though many sites will obtain a NEMA Enclosure to protect any measurement devices or control/communication equipment, a high industrial grade Ethernet Switch with Wide Temperature Operating support is important.
Antaira’s Industrial Managed Switch families are designed to contain open IEEE standard technologies, IEC Industrial Grade Test Level, High MTBF, and Wide Operating Temperatures of – 40 to 75 Degree C to support any Harsh Environment within a WWTP.
Cost Effective
Antaira’s Industrial Managed Switch families are designed to focus on Industrial Environment Networking, and provide a User-Friendly Web Console design that is easily understood and applied, even by personnel with limited experience in networking and communications. This ease of use, and cost effective solution makes it a very important method of networking for overall WWTP applications.
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