October 1, 2009
Automation can provide assistance with overall plant maintenance, but make sure these items receive proper attention for their own maintenance.
by Garrett Forkner and Andy Rieland
It’s safe to say that some of the greatest advances in aggregates processing equipment in recent years have been made in the automation arena. And while the ability for producers to automate such functions as ticketing and billing has been around for at least 30 years, the past 10 years have seen tremendous progress in technology that allows for better equipment performance and more proactive equipment maintenance. Automation technology has improved plants’ abilities to produce material with more consistency, better quality, and greater productivity. At the same time, real-time automated equipment monitoring helps reduce downtime by tracking maintenance needs. In fact, there are automated systems available that can even remotely and automatically make some repairs.
In short — automation has made our lives and our jobs easier.
A high-tech watchdog
It used to be that producers only added automation capabilities to their plants as part of a new equipment acquisition. But today, existing equipment can often accept automated controllers as a retrofit. And this automation typically provides anything from basic machine control to a high level of process control to maintenance and service control.
Most companies, when they seek information about automation, are actually looking for assistance in maintaining the plant. And at the most basic level, an individual automated plant will monitor operational hours to better track scheduled maintenance.
But depending on the automation package the producer selects, a cone crusher package, for example, will enable the system to also oversee such things as differential pressure, checking the amount of coolant and the filter condition in the coolant system, and monitoring temperature and flow differentials in the supply and return lines. By monitoring the level of lubricant in the system, the automation software can help to maintain required temperature parameters. Cone crusher automation can track total motor hours, hydraulic pumps, lube pumps, main drives, and bearing temperatures for longer bearing life. If the cone crusher is a bushing-type model, the automation system often can measure for bushing wear to prevent catastrophic failure.
As for providing the crusher maintenance itself, there are currently automation packages for gyratory crushers on the market that can include such functions as automated greasing systems, which will grease the bushings as a system subcontrol. And because a primary gyratory crusher is sometimes located hundreds of yards or even miles from the rest of the plant, it can be configured to run independently or tied in to the rest of the plant, based on the producer’s needs. Its protective functions and alarms can still be set to provide alerts in the main control room.
For operational controls, an automation system can manage the feed to the processing equipment, and it can protect crushers from overload situations. It usually will handle the latter by sounding an alarm, correcting the loading, or shutting down the equipment. The automation system can track pressure for clamping and the tramp release system. Most systems will automatically adjust crusher settings for production needs or to compensate for liner changes, and they will alert maintenance personnel when it is time to change liners. And if the automated sensors detect problems, they can be configured to shut the equipment down, or they can work to eliminate the problem without shutting down the equipment by sensing variables and making adjustments.
With all of these capabilities, it might seem that an automation package would render human operators obsolete. But today’s automation packages really can’t replace the operator or field service personnel. They are, however, a big assistance in pinpointing and narrowing down the causes of problems. Additionally, automation systems provide safety benefits because remote sensing typically allows for measurement without contact. Even a basic automation package helps with troubleshooting because the data that’s collected can (and should) be checked regularly for trending, which can be interpreted to pinpoint an issue. So, for example, if the operator notes the system re-pressurizes over and over again, he or she should realize it’s not working properly and schedule a shutdown for service.
Improving performance and the bottom line
Automated packages can also help to improve overall plant performance. By logging production, the system allows the plant operator to track productive and unproductive time, so that he or she can analyze the data and compare it to the material produced. Any data can be trended, interfacing off the process equipment to provide operators and supervisors with such information as maintenance needs, schedules, and downtime hours. The operator can then adjust the plant for better performance. Historical data can be tracked remotely or onboard for higher-level management of overall site performance. All of this also helps when tracking the bottom line for the cost of operation.
In a nutshell, real-time monitoring maximizes productivity and reduces downtime by helping to identify bottlenecks, tracking equipment performance, scheduling maintenance, and troubleshooting problems. From a proactive maintenance standpoint, an automated system helps schedule and plan preventive maintenance. From a service standpoint, trending helps operators to troubleshoot, and then plan a plant shutdown and order parts before a failure occurs.
IT issues and technology advances
Advances in technology have created the ability for automation manufacturers to visit a plant’s automation system remotely to help maintain the software portion of the system. While remote service capabilities are not meant to replace a plant visit, remote software maintenance allows the manufacturer to provide system surveys, software product updates, software extensions, and troubleshooting.
Just as with home computers, developments in information technology (IT) can create issues, rendering older software and hardware obsolete. Changes in software seem to come at an alarming rate. Unfortunately, plant owners no longer need to only worry about upgrading a control system during a new equipment acquisition. Because of this, it’s important to keep PC and Windows-based controllers up to date with software and, less frequently, hardware updates.
It’s important to make sure software updates are followed and provide regular checks for security risks — this is done to avoid risks of viruses, hackers, and even accidental harm from an employee downloading a game. The risks grow when the plant is connected to an Intranet or the Internet. In the latter case, manufacturers usually recommend the implementation of a firewall. Also, as a rule of thumb, Microsoft seems to come out with a new Windows operating system approximately every four years. New functionalities and features might mean there is a need to update software or hardware for the system — before it becomes obsolete.
The advantage of remote service capabilities is that the customer avoids downtime and the cost of a field service call, while usually realizing higher performance of the automation system. A DSL, fiber optic, or cable Internet connection is best for remote access to the automation system, although this is not always possible, given the remote nature of some aggregate operations. In this case, a connectivity solution could be provided through radio link or satellite connection.
System maintenance begins with the order
Without a doubt, an automation system helps to maintain aggregate processing equipment. But in an arguably dirty environment, what’s the best way to maintain the automation package itself? Who watches the watchdog?
Maintenance of the automation system begins at the ordering process. Producers should be familiar with the location and operating climate within which the system will work. Specify this information to the automation manufacturer or contractor so he or she can design the correct type of enclosure for programmable logic controllers (PLC) and terminals. The National Electrical Manufacturers Association (NEMA) provides ratings for panel seals to indicate their resistance to such environmental concerns as wet or dusty conditions. The main or mobile command center (MCC) building can also be protected against the environment. Keep temperatures in mind — for the high end and low end of tolerances. Additional environmental control features can be added for the system, such as heaters for winter and air conditioning for hot climates, which could indicate a need for specific ductwork.
When specifying the order, producers should keep in mind, as well, where the human-machine interface (HMI) will be sitting — whether in the central control room or in a remote area. Location can determine a need for a climate-controlled enclosure. And while it might seem that a PLC would be more cost-effective, keep future needs in mind with the automation order. For example, a touch screen monitor is actually easier to swap out down the road than a manual panel that needs diagnostics and greater work at replacement.
At the planning stage, good communication with the system developer will make the installation go more smoothly for everyone involved — when both parties know not only what is on site and the facility’s climate, but also what’s being integrated with the automation. Communication will ensure return on investment, ultimately protecting equipment assets down the line.
Good housekeeping should start with the installation. For purposes of smoother installation, and easier inspections over time, make sure the contractor installs and clearly labels the cables. It might take a little longer to neatly lay in all the cables, but it will pay off in the long run if a need arises for troubleshooting.
Today’s sensors are actually very rugged sensing elements. Different sensors are made for different environments, so as long as the designer/manufacturer knows environmental parameters, the system’s sensors should be designed to take the daily abuse dealt out in any given setting. But no matter how rugged a sensor might be, misuse or abuse will cause failure. Something as simple as a hose rubbing a sensor limit switch will ultimately ruin the sensor. Make sure that, during the installation, sensors are placed in an area that will minimize their contact with the environment. It’s understandable that there are some limits to where sensors actually can be placed. An enclosure for them is the best scenario.
Regular maintenance tips
Daily: As part of a pre-startup routine, verify that the system is reading and providing information; verify that there are no issues between the sensor and the HMI system — i.e. the computer. Basically, any parameter that might cause the machine to shut down should be checked daily within the system — such as lubricant pressure.
Weekly: Monitor trending. For example if a bearing temperature is rising, it could signal impending failure. Schedule the maintenance before it causes unplanned downtime. Check for dust buildup, corrosion, and other environmental effects on sensors, controls, and equipment units. If the controls and/or sensors are dirty, clean them.
Monthly: If control enclosures are exposed to any sort of climate extremes, whether heat, cold, or moisture, do a thorough visual inspection on a monthly basis. And keep general housekeeping in mind as time goes on. Protect all cables and lines not only from dusty environments, but also other equipment. For instance, dripping oil on cable labels will disintegrate the labels and render them unreadable when it comes to troubleshooting or maintenance needs.
Annually: Every installation is different because every application is different. From the size of the material to be processed, to the environmental and climate conditions, all of these parameters work together to create different conditions for the automation system that helps to run the processing equipment. Most manufacturers recommend an annual preventive maintenance visit for automation systems. During a maintenance visit, the specialist will test system functionality, revise configurations if necessary, adjust and calibrate the system, update the software, and provide additional training for the daily system users.
Producers are adding automation to their operations — not only with new plants, but also as part of retrofitting existing operations. Automation can provide anything from basic machine control to a high level of process control to maintenance and service control. Automated packages help improve the bottom line through real-time monitoring that maximizes productivity and reduces downtime by tracking performance, scheduling maintenance, and troubleshooting problems. It is important that the automation package is installed with the correct specifications for climate and environmental protection; and by following recommended system checks, operations can ensure their systems function properly for the long-term with minimal problems.
Garrett Forkner is product support engineer for FLSmidth Excel. He has a bachelor’s degree in mechanical engineering with six years of experience in automation and controls. He can be contacted via e-mail at firstname.lastname@example.org. Andrew Rieland is manager of electrical design for FLSmidth Inc. He has a bachelor’s degree in electrical engineering, a master’s in business administration, and seven years of experience in machine control systems. He can be contacted via e-mail at email@example.com.