The most valuable asset for many utilities is the distribution system. It is also one of the most difficult assets to manage because of the geographic dispersal, dynamic nature and sheer number — for many utilities, millions — of distribution assets that have to be managed.
Previously at Public Service Company of New Mexico (PNM; Albuquerque, New Mexico, U.S.) the standard practice for inspecting the distribution system was to hand the linemen a stack of paper forms and send them out into the field to patrol a section of the system. The linemen would return with their stacks of paper forms, which were dutifully placed in a file cabinet and, after gathering dust for a period of years, later disposed of. Emergency maintenance conditions discovered during the patrols were addressed, but the vast majority of maintenance conditions and the history of the information pertaining to those conditions were lost. Little benefit was derived from the inspection process, because aggregating the individual paper inspection forms into meaningful business intelligence would have been time consuming and costly. Continuing the paper-form method of inspection would have resulted in the same guesswork regarding where to apply limited maintenance dollars to best maintain the distribution system.
This process was obviously inefficient and ineffective, and over time, it became completely unacceptable for a variety of reasons. Increased regulatory reporting requirements, relentless pressure from executive management to reduce costs and improve the bottom line, while at the same time focusing on customer demands for improved reliability, together dictated that something be done.
Initially, PNM sought to identify and purchase an existing solution to meet its requirements. The main requirements were the ability to:
Provide high-speed logging of the condition of lines, poles and distribution equipment using mobile computers.
Prioritize and summarize work that needs to be done to keep the distribution system in good repair.
Track the overall condition of the distribution system to help in the budgeting and planning of system maintenance.
Several existing systems were evaluated, but attempts to purchase a turnkey system were unsuccessful. PNM's answer was to embark on the development of a system that would meet its requirements.
Starting in the spring of 2001, PNM began working with EDM International Inc. (Fort Collins, Colorado, U.S.) to develop and implement a distribution inspection and asset management system that would supplement its existing AM/FM system. That collaborative effort resulted in the Automated Line Patrol System (ALPS), which is a mobile electric distribution asset management system that emphasizes asset condition assessment and repair tracking. This system has enabled PNM to more closely track the actual condition of each component and better schedule maintenance as appropriate.
Development and Implementation Plan
PNM developed and implemented ALPS as a four-stage project:
Stage 1: Develop and deploy overhead line and pole inspection, and reporting functionality.
Stage 2: Develop overhead equipment and services inspection functionality.
Stage 3: Develop ground line and underground equipment inspection functionality.
Stage 4: Incorporate inventory capabilities.
The initial driver in determining how the project was staged was the availability of funds. In 2001, the money was available for developing and implementing Stage 1 of the project. Development of ALPS began in earnest in the spring of 2001. By October 2001, Stage 1 was complete and eight contractors were in the field capturing inspection information on the distribution system. This effort continued through the end of 2001.
During the development of Stage 1, the speed with which an inspection could be performed was always in mind. Simply put, there was so much to inspect and so little time to do it in that the rate at which the inspections took place had to be high but also accurate. The average inspection rate achieved was 100 poles/day per inspector. In 10 weeks, inspectors examined 49,000 poles. Capturing this large volume of distribution-system condition data has given PNM insight into the overall condition of its overhead distribution system. This insight has allowed PNM to focus its maintenance dollars most effectively on the higher-priority maintenance items.
Stage 2 of the project, the development and implementation of overhead equipment and services inspection functionality, was completed in 2002. Stage 3, the development of pole ground line and underground equipment inspection functionality, was completed in 2004. Stage 4, the ability to conduct field inventory with GPS coordinates, remains to be implemented at PNM, although the functionality has been developed by EDM. Extensive field-data collection efforts like that performed during Stage 1 have not been undertaken due to financial constraints in recent years, but the application is still used to report conditions observed during regular operations and to track the maintenance performed as a result of the conditions reported during Stage 1.
The ALPS software was developed with the end user in mind. PNM linemen were involved in the development of ALPS from the beginning. For the most part, everything is located on one screen with other smaller input screens popping up as necessary, so there is no toggling between several screens. This keeps the inspection fast. List boxes and drop-down selection boxes were utilized whenever possible to eliminate typing by the inspectors. The only typing required of the inspectors is for comments, if they choose to enter any.
Throughout the project, a flowchart approach was used to design each module. Fig. 1 depicts the flow chart created for illustrating the process for recording various problems associated with an insulator.
PNM does not physically number its poles, so without a GIS or mapping system, there would be no way of knowing what pole number to record observed conditions on. For this reason, ALPS was linked to PNM's existing Intergraph GIS system, which allows the inspectors to see where they are on the map using GPS tracking and to select a pole from the map, automatically opening and/or moving to that pole record within ALPS. EDM worked with Graphic Technologies Inc. (GTI; Madison, Alabama, U.S.) to create this functionality through Intergraph's FieldView application. If the pole number is known, simply typing it in or selecting it from a drop-down list within ALPS will take the user to that pole.
- Recording conditions during routine patrols
There are three separate forms on which conditions identified during patrols can be recorded: one for pole/structure components, a second for overhead equipment components and a third for underground components. EDM developed the condition recording functionality in such a way that the choices for each item and subsequent paths are all determined from tables within the database, allowing for easy modifications without having to modify any code within the application. A utility can choose to enter any or all of the following items for any of the major components: condition, material, material type, service type, quantity, maintenance priority, estimated crew size, estimated man-hours and comments.
The selections for each of these items are limited based on the component or combinations of previously entered items, thereby expediting input while minimizing the chance for errors. Every selection is made by clicking on the desired item in the list. Each mouse click brings up the next selection box that is short-listed with the available items. Fig. 2 illustrates the process of recording a pole condition. Once the pole button is selected, a list of possible pole conditions appears, and once a pole condition is selected, a list of pole materials appears. This process continues until the maintenance priority list appears and the condition is logged.
While pop-up screens are used to ease input, a summary of the entries is shown on the main screen (Fig. 3).
The rating system developed for classifying the maintenance conditions found during the inspections uses four priority levels:
- E = Emergency repair needed within 24 hours
- 1 = Repair needed within one month
- 2 = Repair needed within one year
- 3 = Repair needed within four years.
The PNM linemen worked with the PNM engineers and EDM developers to create the rating criteria for each potential maintenance condition. Extensive training was conducted to help ensure consistency between inspectors.
Once the conditions are recorded, the inspectors can enter estimates for crew resources necessary to make the repairs. This information can be used to further refine budget estimates.
- Pole groundline inspections
In an effort to record and track all distribution inspection and maintenance data within one application, a pole groundline inspection module was created. Contract crews can use this module to record their inspection activities directly within ALPS, or the electronic data provided by contract crews can be converted into the required ALPS format. One advantage of using the module in the field is that it incorporates the D-Calc pole damage assessment software that was created by EDM, which allows for maintenance decisions to be made based on more quantitative information rather than traditional minimum shell-thickness rejection criteria. The inspectors can perform a damage assessment at any location along a pole by clicking on a button, which launches the D-Calc application and passes relevant information to the application. The inspectors then model the damage and push a button to calculate remaining pole properties based on the damaged section. Results are passed back to ALPS, where they could be used to make or modify recommendations or further prioritize pole maintenance activities (Fig. 4).
- Automatic photo acquisition
When performing inspections, it is important to do everything possible to help ensure that the proper maintenance recommendations are being made. The addition of automated photo acquisition has not only helped with the development of training materials but also allows for maintenance recommendations to be discussed and possibly modified by other individuals back at the office without the need to go back into the field. All an inspector has to do is take a picture of the condition with a digital camera, plug the camera into the computer and click on a button in ALPS to acquire the image. A preview of the image is displayed and, once satisfied with the image, the inspector can click a button to link it to the inspection record (Fig. 5).
Stage 1 Deployment Results
The following results were obtained from the Stage 1 inspections of 49,000 structures on the PNM distribution system (Fig. 6).
More than 25,000 maintenance items were identified during the Stage 1 inspections. PNM now possessed the data necessary to make informed maintenance decisions. The information depicted in Fig. 6 is high-level data. In order to make use of such data, the capability to turn it into more specific information was necessary. ALPS offers this capability through many reporting options.
Reports can be generated in ALPS using any of the selection criteria or any combination of these criteria. For instance, if it is desirable to know the 20 most frequent maintenance items on the distribution system by component type and the associated condition, a report could be generated (Fig. 7).
With this specific information comes knowledge. The report shows that equipment requiring the installation of bird guards constitutes PNM's largest number of “Priority 1” maintenance items (Fig. 8). With this knowledge, action can be taken by instituting a program to install bird guards where required. Another ALPS report can be generated to determine where the poles that require bird guards are located. By generating an additional report within ALPS, we can also determine the crew type needed and the number of hours required to accomplish the work.
At this point, all of the information necessary to produce tangible results is available: the maintenance item, the priority of the maintenance, the location where the maintenance needs to be performed, the quantity of bird guards needed, the crew type, the equipment required, and the man-hours needed to complete the work can all be determined.
PNM's distribution inspection program has progressed and improved considerably from the days of paper inspection forms. PNM has a tool in ALPS that can quickly and accurately provide critical, specific information on the health of the distribution system. ALPS allows for the efficient and effective planning and scheduling of activities associated with the inspection and maintenance of the distribution system, and increases efficiencies of overall corporate asset management. PNM has consistently been in the top quartile in SAIDI minutes since 2001, receiving the No. 1 ranking in 2001. Better asset management through the use of ALPS has contributed to these results. Ultimately, ALPS enables PNM to develop strategies and solutions that turn data into information, information into knowledge, knowledge into actions, and actions into results.
Wes Wilson is a senior engineer responsible for transmission maintenance and asset management tools for the Public Service Company of New Mexico. Wilson, who holds a BSME degree from New Mexico State University and an MBA from Texas Christian University, also directed the successful implementation of TAMIS at the Public Service Company of New Mexico. email@example.com
Bill Ranken is a professional engineer responsible for distribution automation and process improvement for the Public Service Company of New Mexico (PNM). Ranken has directed the successful implementation of outage management, geospatial information, distribution SCADA, computer-based line patrol and real-time boiler control systems. He also is chairman of the reliability improvement process analysis team at PNM. Ranken has a BSEE degree from the University of New Mexico and is a registered professional engineer in New Mexico. firstname.lastname@example.org
Michael R. Abbey is the lead for software development and marketing activies at EDM. He received the BS degree in architectural engineering in 1994 from the University of Wyoming and has been employed as a structural engineer, application analyst and project manager at EDM since 1996. Abbey is involved in the EPRI-sponsored AIM (Assessment and Inspection Methods) project developing methodology for inspection of overhead transmission lines. email@example.com