Improving monitoring and control hardware cost at Totten Mine

Improving monitoring and control hardware cost at Totten Mine Ozzy Flores, Enrique Acuña Totten Mine, Vale Canada Limited, Sudbury, Ontario, Canada Totten Mine recently completed the project development, production ramp up phase and is running at full production, with a daily rate of 2200 tons. Totten is benefiting from an efficient automated ventilation system that includes control of main and auxiliary fans which can be started and shut down at any time from the surface central control room. In order to generate this level of control the mine utilizes a combination of industrial communication protocols (Profibus, Modbus) and Ethernet based communications (Profinet, Modbus TCP/IP). During the project phase of Totten Mine, construction relied heavily on the industrial communication protocols for monitoring and control of underground ventilation equipment such as fans, doors, dampers and ventilation monitoring stations. Since achieving full production, Totten Mine has made advances in the ability to monitor and control the ventilation equipment over Ethernet. As part of the current efforts to minimize and reduce capital and operational costs at the mine site, Totten Mine completed a study to compare the automation and control hardware currently in use with new proven technologies available in the market. The idea was to identify technologies with the potential to reduce the implementation cost for new mining levels that will be developed as part of the life of mine plan; but without compromising the current communication and control capabilities. This paper presents the initial state of the automation and control before the study, the alternatives considered, the discussion about the alternatives, the estimated savings and the final solution chosen for the mine which is currently under implementation. 1 Introduction Totten mine is one of six Vale mines in the Sudbury basin. It is located about 40 km South West of Sudbury and is the newest operating mine. During the project phase Totten was equipped with state of the art technology in terms of monitoring and control for ventilation systems. The mine has realized the benefits of such systems mainly in three areas: health and safety, production and energy savings. Monitoring the different levels and ramps from the surface control room enables the monitoring of gas and temperature conditions during the complete shift. Additionally, within the ABB 800xA program, alarms are set at different thresholds to alert if conditions change and ensures a safe underground environment for employees. Due to the capacity for controlling main fans speed, doors and regulators, the control room operator can allocate different airflow demands in different levels based on operation requirements and modify them during the shift as requested within the ventilation system limitations. As a result, the current manual control system installed at Totten mine has been able to deliver a 25% savings in terms of energy consumption compared to the same ventilation system running at full design speed. These savings have being achieved mainly at the primary level by adjusting the speed of main fans feeding the mine volume requirements and with the use of dampers in a PID (Proportional Integral Derivative) loop with airflow sensors to modulate the air volume across a level according to the expected requirements. Through the past few years of gained experience and cost reduction initiatives, the automation department has identified potential solutions for reducing the cost of the implemented systems. This has been done

without compromising current capabilities and also enabling an enhancement of system features. This paper introduces the initially installed communication and control design system and presents alternatives considered to improve the overall cost. A discussion on the relative costs and results is presented with details of the proposed new solution for the mine. 2 Initial state The initial design was composed of the typical infrastructure found at most underground mines. What is referred as the typical installation considers a controller (PLC) located in the area or level with motor control and instrumentation hardwired back to the controller. The initial design at Totten included DCS controllers located in the Electrical Sub Station (ESS) on each level access. The underground controllers communicated back to surface via an Ethernet based Process Control Network (PCN) allowing the monitoring and control signals to be displayed in Totten s Central Control Room as illustrated in Figure 1. CENTRAL CONTROL ROOM (SURFACE) ABB RIO PANEL - VMS VFD ABB RIO PANEL ABB RIO PANEL PROCESS CONTROL NETWORK U/G DCS CONTROLLER Profibus Network PCN Ethernet Network Analog / Digital Signals HPSSD Figure 1 Initial design overview schematic DAMPER (A) DAMPER (B) The initial design of the U/G ventilation control system included the following hardware components in order to provide remote control and monitoring capabilities to the Central Control Room. ABB DCS Controllers: These controllers were located at each Underground Electrical Sub Stations (ESS). The controller provided the DCS logic required for monitoring and control for the U/G Ventilation equipment located on the level. Profibus Network: Establishing communication between the DCS controllers and the underground ventilation equipment was done via an industrial communication protocol called Profibus. When initially designed, Profibus was the preferred and proven communication protocol between the DCS controllers and the underground ventilation equipment.

Underground Ventilation Equipment: The initial Underground Ventilation Equipment that was controlled comprised the following: o Fans (On/Off): Fans that required On/Off control utilized an ABB Universal Motor Controller () in order to provide overload protection as well as monitoring and control. Communication between the s and the DCS controller was established via Profibus. o Fans (Variable Frequency Drive): Fans that required variable speed control utilized an ABB Universal Motor Controller (VFD) in order to provide monitoring and speed control. Communication between the VFD s and the DCS controller was established via Profibus. Initially main fans and some of the largest auxiliary fans were equipped with VFD s. Due to operational issues to keep VFD s running underground only the main fans on surface are currently equipped with VFD s. o Ventilation Monitoring Stations (VMS s): Requirements to monitor CO, Airflow, Temperature (dry bulb), and Relative Humidity throughout the mine were initially designed with ABB Remote I/O (RIO) Panels and hardwired transmitters. These ABB RIO Panels were designed to have individual transmitters for CO (Dräger), Airflow (Accutron), Temperature and Relative Humidity (Vaisala) individually wired to analog inputs on the ABB RIO Panels. Communication between the ABB RIO Panels and the DCS controllers was established via Profibus. o Flextor Dampers: In order to control the airflow volume on each level the Flextor Dampers utilized Auma Actuators to modulate large mechanical Dampers to the open area required to establish the airflow requirements. For monitoring and control the initial design utilized ABB Remote I/O (RIO) Panels to hardwire the Auma Actuators control and monitoring signals. These ABB RIO Panels were designed to have the position feedback, fault indication, mode operation (local or remote), and desired set point wired to analog inputs and outputs as well as digital inputs. o High Pressure Steel Sectional Doors (HPSSD s): These doors help control ventilation throughout the mine by maintaining an open position to allow a desired airflow through the door. In order to monitor and control these doors the initial design only provided a desired set point via an analog output signal and position feedback via an analog input signal from the nearest DCS Controller or the nearest VMS. These doors were used as ventilation controls in locations that required infrequent access and still required regulation, for example the bottom of certain ventilation raises or ventilation transfer drifts. The initial ventilation control system did not have redundancy within the DCS controllers; which was problematic in the project development phase due to the frequent communication failures from damaged Profibus cables. When communication was offline the remote operation of fans, VMSs and monitoring was not available. However, the automation team developed a control philosophy that allowed full local control from pushbuttons on the fan starters so that the ventilation equipment did not have to rely solely on the DCS logic and Profibus communication network to establish control.

The cost of completely automating the underground ventilation infrastructure was significant; with the majority of the cost associated with the requirement of ABB hardware in order to establish Profibus communication between the underground DCS controllers and the fans ( s), RIO Panels (VMS s and Flextors). An additional cost of Engineering was required to develop multiple schematics and wiring diagrams as well as labor costs for installation and wiring all the various electrical and communication panels. 3 Control strategies considered In an effort to increase automation capabilities and at the same time reduce the cost of extending the automation infrastructure at Totten mine, the Automation team began to look at alternatives in hardware and technology. The objective was to minimize costs, but maintain or improve the control and monitoring capabilities of the existing hardware. The options were evaluated based on the following criteria: cost, technical capability or functionality, ease of installation, maintainability and best practices from other mines if pertinent. It is important to note that at the beginning of the evaluation process the communication capabilities of the DCS controllers over Ethernet had not been tested. Therefore, the initial hardware alternatives focused on finding a solution that was able to communicate over Profibus. However, the testing of Ethernet was being conducted in parallel to the hardware alternative evaluations. As the evaluation continued the focus shifted to fully explore the capabilities of the DCS controller over Ethernet and the evaluations of alternative hardware expanded to include solutions that were able to communicate over Ethernet instead of Profibus, as the ability to use Ethernet would allow the mine to leverage the extensive underground Ethernet and Wireless network installed at Totten. Below is a breakdown of each ventilation hardware component and the major items the Automation team focused on improving. 3.1 Ventilation Monitoring Stations (VMS) The high cost of RIO Panels, associated Engineering requirements (schematics, loop diagrams, wiring diagrams and network drawings among others) and Installation factors forced the team to look at alternatives. The evaluation started with solutions that would utilize a communication protocol rather than hard-wired signals back to the DCS or RIO Panels. Figure 2 illustrates the original design. The different costs considered for the VMS are listed as follows. RIO Panels o ABB panel Individual Transmitters o Accutron M Series unit o Dräger (CO sensor) o Vaisala (Dry bulb temperature and relative humidity) Engineering Costs o Schematics o Wiring Diagrams Installation o Large Panels o Extensive Wiring o Numerous Cables

Figure 2 Original Ventilation Monitoring Station Design ABB Remote I/O Panel The options considered for the VMS s are listed as follows: Accutron Profibus: Accutron provided a potential solution that utilized a Communication Gateway (Anybus) to convert Modbus to Profibus as presented in Figure 3. However the solution was a proof of concept with the risk of not providing reliable communication back to the DCS. The solution also required extensive configuration setup to get the unit online. Figure 3 Accutron Profibus option Maestro Profibus: Maestro provided another potential solution that utilized and completely integrated a system that was able to provide not only Air Flow but CO, RH, and Temperature sensors, all in a single integrated unit. The unit utilized a Modbus communication link to communicate to each sensor which allowed the unit to transmit this data over Ethernet (Modbus TCP/IP) as presented in Figure 4. Figure 4 Maestro Profibus option However, at this point the Ethernet communication capabilities of the DCS were still not proven. Therefore, Maestro was required to provide a Profibus solution in order for the mine DCS to communicate to the Vigilante unit. The proposed solution also required a Communication Gateway (Anybus) which again required extensive configuration setup to bring the unit online; however, the communication was seen to be reliable.

Maestro Modbus TCP/IP: Since the Maestro Vigilante already had Ethernet (Modbus TCP/IP) communication capabilities it was the preferred solution to test with the DCS. At this point the DCS communication capabilities with Ethernet had been proven and the mine was ready to begin communicating to devices on the Ethernet network as presented in Figure 5. However the Profibus connection was maintained until the Ethernet network connection proved to be reliable. Figure 5 Maestro Modbus TCP/IP option VMS hardware selected: Totten s automation team selected the Maestro Vigilante solution for Ventilation Monitoring Stations moving forward, as presented in Figure 6, until such a time when other equivalent competitive solutions are readily available in the market. Figure 6 VMS hardware selected option The ability to communicate via Ethernet (Modbus TCP/IP) and provide additional diagnostic capabilities was a major factor in the decision to select this device. The compact size and integration between all the sensors in a single panel was also a benefit with the Vigilante. The most advantageous feature of this device is its ability to be powered over Ethernet. With the fully integrated instrument cluster, the engineering cost for individual schematics and wiring diagrams were eliminated and with the ability to be powered via Ethernet (POE), there was no longer the need for installation of multiple cables. Essentially this reduced the installation time to that required to erect a small panel and attach a single Category 5 (CAT5) cable. The initial estimate indicated that a savings of 40% of the initially installed system could be achieved. 3.2 Flextors Dampers The same cost of the RIO Panels, Engineering requirements (schematics, loop diagrams, wiring diagrams, network drawings, etc), and Installation factors also lead to a review of options for

the Flextor Damper automation requirements. The evaluation started with reviewing solutions that would utilize a communication protocol rather than hard-wired signals back to the DCS or RIO Panels as presented in Figure 7. The different component costs considered for the flextor damper are listed as follows: RIO Panels o ABB panel Limited Control / Monitoring o Position Feedback o Position Set point o Fault Feedback o Mode of Operation Local/Remote Engineering Costs o Schematics o Wiring Diagrams Installation o Large Panels o Extensive Wiring o Numerous Cables ABB RIO PANEL DAMPER (A) DAMPER (B) Figure 7 Original Flextor Damper Design ABB Remote I/O Panel The options considered for the flextor damper are listed as follows: Siemens RIO Profibus & Profinet: Evaluation of the RIO hardware from Siemens included determining the cost of the hardware and designing a sample panel layout. Despite the fact that the RIO solution met the communication and hardware requirements the cost of the hardware yielded minimal cost savings in comparison to the existing ABB solution. Also, the size of the panel in order to accommodate the hardware was of similar size to the existing solution.

Maestro AD4 / AD8 Ethernet Remote I/O Profibus: Evaluations of the AD4 /AD8 RIO hardware from Maestro with Profibus communication included testing the hardware in the Totten test environment in order to determine if the hardware was a viable alternative. Since the Ethernet capability of the DCS controller was not proven at this point, a protocol gateway that would convert the native communication of the AD4 (Modbus TCP/IP) to Profibus needed to be incorporated as presented in Figure 8. This proved to be very cumbersome in terms of initial configuration and required individual configurations dependent on the device the AD4 was controlling (VMS or Flextor). MAESTRO AD4 DAMPER (A) DAMPER (B) Figure 8 Maestro AD4 / AD8 Ethernet Remote I/O Profibus option Maestro AD4 / AD8 Ethernet Remote I/O Modbus TCP/IP: Evaluations of the AD4 /AD8 RIO hardware from Maestro with Modbus TCP/IP communication included testing the hardware in the Totten test environment in order to determine if the hardware was a viable alternative as presented in Figure 9. The testing concluded that communication over Modbus TCP/IP was a viable alternative and included the benefit of eliminating the protocol gateway (Anybus Gateway) that was required in the initial evaluation of the Maestro AD4 / AD8 RIO. Another advantage was that the unit was able to be powered over Ethernet (POE). Auma Actuator Profibus: The Automation team initially considered communicating directly to the Auma actuators via Profibus; and evaluated the communication parameters available via Profibus in order to determine if the appropriate controls and monitoring parameters were available. This evaluation consisted of reviewing the communication manuals and discussions with the Auma manufacture, where it was determined that Profibus would be a viable alternative instead of hardwiring the signals to a RIO panel. The cost analysis determined that there was only a slight increase in price associated with equipping the Auma actuators with communication capabilities.

DAMPER (A) DAMPER (B) Figure 9 Maestro AD4 / AD8 Ethernet Remote I/O Modbus TCP/IP option Auma Actuator Ethernet (Modbus TCP/IP): At this point in the evaluation process, the Automation team had proven the Ethernet capabilities of the DCS controllers. Therefore, the Auma actuators were able to be evaluated through communication via Ethernet and proved to be a success by easily integrating the Ethernet Auma actuators into the Totten test environment. Full control and monitoring capabilities were established and it was discovered that there were significant diagnostic features available by utilizing the communication capabilities of the Auma actuator instead of hard wiring the signals to RIO panels. Flextor Damper hardware selected: Initially the Automation team selected the Maestro AD4 RIO solution for interfacing with the Flextor Damper Auma Actuators and began implementing the Automation designs for several levels. However, after the completion of the Ethernet testing with the DCS Controllers, the Automation team chose to operate the Flextor Dampers with Auma actuators with Ethernet communication as presented in Figure 10. DAMPER Figure 10 Flextor damper hardware selected option Despite a small increase in price for an actuator with Ethernet, the overall cost of the Automation of the Flextor Damper is greatly reduced because the RIO panels are no longer required. Eliminating the RIO panels reduced the cost of hardware, engineering requirements (Schematics, Wiring Diagrams, and Panel Layouts) and installation since previous multiple runs

of cables and wiring were reduced to termination of a power cable and a single communication cable (CAT5). 3.3 On/Off Fan Control The initial design considered local DCS controllers at each ESS and communication to fan starters utilizing Profibus in addition to the ABB hardware utilized to establish this type of communication between the DCS controller and the s. This strategy had a higher fixed cost which initiated the automation team to look at alternatives for On/Off fan control. The component costs considered for the on/off fan control are listed as follows: Fan Starter Hardware o ABB o 24V DC Power Supply o Profibus Connector DCS Hardware o Local DCS controller required o Profibus Communication Modules Engineering Costs o Schematics (Fans, Pumps, Jumbo, DCS Panel) o Wiring Diagrams (Fans, Pumps, Jumbo, DCS Panel) o Panel Layout (DCS Panel) Installation o Large Panels (DCS Panel) o Extensive Wiring (Fan Starters, DCS Panel) o Numerous Cables (Fans Starter, DCS Panel) The options considered for the On/Off fan control are as follows: Procentec Profibus Hub: The first alternative evaluated was the Procentec Profibus Hub which was a more cost effective solution by providing multiple network Profibus connections to a single DCS controller. Rather than multiple ABB Profibus communication modules within the DCS cabinet, the Procentec Profibus Hub allowed for a single ABB Profibus communication module; which reduced the number of communication modules resulting in a significant savings since these modules are very expensive. Schneider Electric - Tesys T: Another Vale Mine was utilizing the Tesys T for On/Off fan control so it was chosen as a viable alternative to evaluate in order to leverage existing experiences. The Automation team evaluated the Tesys T by successfully integrating a single unit into the Totten test environment. The Tesys T did offer the same remote control capabilities with some additional monitoring capabilities as well as utilizing Ethernet (Modbus TCP/IP) for communication. However, after completing the evaluation it was discovered that the Tesys T could not duplicate the local control functionality that the ABB provided. In terms of cost the Tesys T did offer some cost reduction, the unit itself was less expensive than the ABB and it did not require a separate 24V DC power supply since the unit was able to be powered with 120V AC. ABB 100.3 with Profinet PNQ Module: ABB had released their newest version of the 100, the 100.3, which was able to connect to the ABB PNQ Module.

This module allowed up to four 100.3 to be connected to the PNQ Module. The PNQ module allowed these four s to communicate over Ethernet (Profinet) with a single CAT5 connection. The Automation team evaluated if the combination of the new 100.3 and the PNQ modules offered the same functionality as the existing Profibus s. The 100.3 and the PNQ modules were successfully integrated into Totten s test environment and all existing monitoring and controls were able to be maintained with this new hardware. Figure 11 ABB 100.3 with Profinet PNQ Module option On/Off fan control hardware selected: The Automation team initially focused on reducing the cost of expanding the Profibus network, but with the successful testing of the DCS controller communication over Ethernet (Profinet) between the controller and the newly improved 100.3 it was decided that future levels would utilize Ethernet as the preferred means of monitoring and control for On/Off fans. Therefore, the hardware selected was the combination of the ABB 100.3 and the Profinet PNQ Module. The savings included eliminating the need for multiple Profibus Communication Modules since four s would be able to be communicated to the DCS controller with a single Ethernet connection as opposed to requiring the expensive Profibus communication modules. The 100.3 are also able to be powered by 120V AC thus eliminating the need for a 24V DC Power Supply for each fan starter. However, the most significant savings realized by utilizing Ethernet instead of Profibus was eliminating the need for the Profibus connectors since the cost of a single Profibus connector was almost the price of the itself. Another significant advantage to Ethernet was that it removed the requirement of having the program for each fan reside in the local DCS controller allowing the network connection to be made to any network switch instead of the local DCS. The initial savings was estimated to be at least 60% of the initial hardware cost. Figure 12 presents the end state of the monitoring and control hardware as a result of the modifications previously described. 4 Conclusions Establishing the Ethernet communications between the underground ventilation equipment and the DCS controller proved to be the most significant innovation during the evaluation process. The selection process for each hardware alternative initially began with finding a Profibus solution however with the implementation of Ethernet as a means of communicating to the DCS Controllers the selection criteria changed and the Automation team concentrated on finding a suitable Ethernet solution for each alternative.

CENTRAL CONTROL ROOM (SURFACE) DCS MASTER CONTROLLER SURFACE UNDERGROUND PNQ22 PROCESS CONTROL NETWORK & SHARED NETWORK DAMPER VENTILATION MONITORING STATION Ethernet Network (PCN or SHARED) Wireless Network Figure 12 End state of monitoring and control hardware DAMPER Another significant decision that the Automation team made was to no longer install underground DCS controllers at the ESS. The new control and monitoring philosophy would include the implementation of a Master DCS Controller on surface with communication to the underground ventilation equipment utilizing the Ethernet network infrastructure. This design would allow a single controller to hold all the underground ventilation programming and eliminate the need for constant changes to individual controllers when equipment was installed or removed. The new design essentially eliminated the cost of the DCS hardware, panels, and wiring for future ESS s as well as significantly reducing the installation and logistic cost associated with getting this hardware underground and installed. From a programming point of view the Master DCS Controller would also allow the standardization and optimization of the DCS logic in a central controller. The Automation team could now essentially preprogram the entire ventilation requirements on future levels and if underground ventilation equipment was moved, the underground program would always exist for that piece of equipment, as opposed to transferring the program from one controller to another. The work presented in this paper allowed the automation team at Totten mine to significantly improve the time and cost to install monitoring and control hardware without compromising any of the previously available capabilities and features. In addition, more features became available in terms of the diagnostics capability of the system when required for trouble shooting. Ongoing work is quantifying the initial cost of installing the current system and the savings that have been achieved to-date. Additionally Totten mine has tracked the energy savings obtained through the implementation of the ventilation controlled system to estimate the pay back for future application at other Vale sites.