AUTOMATED RELAY TESTER

Transcription

1 AUTOMATED RELAY TESTER We in C&S are faced with never ending challenges to find ways to improve safety, efficiency and productivity of the services that we render as well as the tasks we perform. At the same time, it seems that we are consistently placed in the position of answering these challenges in an environment of ever increasing scarcity of resources. As we all know, changes in the way we perform our work in C&S come slowly, probably due to the fact that our jobs are so closely intertwined with the issue of safety. However, intuitively we know that if we are performing our work in the same manner as was done a generation ago, we probably need to take a close look at the activity and ask ourselves if there might be a safer or more efficient way to accomplish the task. Such was the thought process behind development of the relay tester on Norfolk Southern that I am pleased to talk about here today. We recognized the challenges of improving the accuracy test results, improving the efficiency of the relay testing process, and improving the accessibility to relay test and inventory data.

2 In an effort to address these challenges, early last year Norfolk Southern entered into a contract with Ultra-Tech Enterprises for the development of a prototype automated relay testing system. The prototype, built to NS specifications by the vendor, was delivered in July of this year. Tester design allows for automated simultaneous testing of 64 relays, and provides for automated recording of test results. Relays are tested without the requirement for removing from the rack or monitoring contact operation. In a moment, I will discuss the tester s design in detail which enables these and other features, but for you to fully appreciate what we were trying to accomplish, it is first necessary for me to briefly describe the most common methodology presently used in the testing of relays. Today, to successfully test a location with vital relays, the following steps must be observed: Present Testing Procedure First, track time must be obtained at the site where testing is to be done. Next, test equipment must be applied. For locations with rack-mounted or plug-in type relays, this requires that relays be removed from the rack and inserted into the test plugboard. Next, energy applied to the coil is manually increased to 2

3 coil saturation found at the full applied voltage, followed by energy being decreased in a gradual manner while observing the relay contacts for heel to front opening, or dropaway. Once dropaway is observed, the measured value at dropaway is recorded. Energy is then decreased to the zero point, followed by gradually increasing until heel to front contact closure, or pickup, occurs. Once pickup is observed, the measured value at pickup is recorded. The above steps are repeated for all relays that require testing at the site. However, due to the volume of train traffic, maintenance personnel would not normally be successful in obtaining uninterrupted test time, but instead, would be required to relinquish and reacquire track time numerous times before testing can be completed. Although there have been a few attempts in recent years to employ modern technology to improve the relay testing process, we at Norfolk Southern believe that these devices did not go far enough in dealing with all the issues that we were most interested in addressing, including the need for increased testing throughput. 3

4 Tester Description Combining a unique yet innovative hardware and software design with commercially available database software, the tester achieves the desired objectives of improving the efficiency and accuracy of the testing process. At the same time, the tester fosters the establishment of databases containing very useful relay specification and test data. To understand how the tester accomplishes these objectives, it is best to start with a brief explanation of the tester s functional diagram. Referring to the diagram, the tester hardware consists of a laptop computer, a server or data router, and nodes connected in a LAN configuration. The laptop computer contains the software that executes the testing process as well as the databases needed for testing. The computer communicates to the LAN through the data router, which controls the LAN and handles communication with the nodes. The nodes are the interface points with the relays under test. Actual connections are made to the relays through use of connectivity devices that are specific to the relay types. 4

5 From a software standpoint, design can be best summed up by describing the three databases used by the tester. These are the manufacturer specification database, the characteristic curve database, and the historical database. In a moment I will briefly describe each, but first, to assist you in understanding these databases, it is necessary for me to make mention the importance preparatory activities to the function of the tester. As I describe these databases and the tester s other operational prerequisites, it will probably occur to you that there are a considerable number of tasks required to prepare the tester for testing. On the surface, these tasks might appear to be very time consuming and maybe even burdensome. However, you should be relieved to find out that many of these tasks are one time activities for the railroad as a whole, with others being one time activities per site. In addition, many of the tasks can be performed before the tester is brought to the field. As it turns out, only a small subset of these tasks are required each time the tester is brought to a site. 5

6 Tester Databases The first database we will examine is the manufacturer specification database. This database is an integral part of the tester, and creation of this database is a one time activity for the railroad as a whole. For the tester to evaluate a relay s performance in terms of pickup and dropaway, the tester must have information on values for these parameters as specified by the relay manufacturer. In addition to these, the database contains other important information needed for evaluation of relay performance such as working parameters, slow acting timing values, and coil resistance. Although we would have liked to have an automated means to enter the data, we found that the wide variation in format of the manufacturer s specification datasheets dictated that this be a manual entry exercise. Considering that this entry was to be done for the many hundreds of models of relays that require testing, this was to indeed be a very time consuming activity. However, the good news is that this is a one time activity due to the tester employing commercially available Microsoft Access as its database software, with the capability to export files to other laptops being used with other testers. In addition, once all relays are entered into the database, Access will allow us to take advantage of 6

7 its timesaving search, sort and query tools in the managing our systemwide base of relays. The second database used by the tester is the characteristic curve database, creation of which also is a one time activity. This database was created for the purpose of achieving one of the tester s primary design objectives, in-rack testing. In-rack testing means that we can test a plug-in type relay without requiring the removal of the relay from its mounting plugboard, but rather, leaving it in the rack. Achieving this requirement meant that the tester would be able to determine relay pickup and dropaway by monitoring the electrical behavior of the voltage across or current through the relay coil, without monitoring the behavior of the relay contacts. Characteristic curves, one for pickup and one for dropaway of each relay model to be tested, were established by evaluating the performance of several representative relays of that model. Since this process included monitoring of the relay contacts for the actual pickup and dropaway points, each characteristic curve is marked to indicate the point at which pickup or dropaway occur. During actual testing, the stored characteristic curves are compared to the measured values which allow establishment of the pickup and dropaway points of the relay under test. In addition to enabling in-rack 7

8 testing, the use of the curves essentially removes the human factor in the interpretation of test results, one of the primary objectives of the tester. Our third and final database is the historical database. This database contains information on all relays that are in service at all the locations where the relay tester is to be used. In addition, this database contains both current and historical test result data for all relays at these locations. In the historical database, there are a number of fields which require definition, including site ID, rack ID, model, catalog or drawing number, serial number and nomenclature. Although the tester obtains this information via manual entry, the tester employs a number of techniques which allows the user to expedite the process. As in the case with the manufacturer specification database, standard Access database data entry templates have been set up to aid the user in the data entry process. This is most easily illustrated by briefly walking through some of the steps required to configure a new location including racks, and the entry of a few relays. First, a new site is defined by entering the Site ID, district, division, milepost and description. Second, the user defines racks by specifying a rack ID along with the number of rows and columns. Next, the user 8

9 defines relays one at a time to the rack, accomplished by double clicking on the appropriate block on the rack grid template, followed by identifying the desired relay model using the relay template. On this panel, specific model numbers can be quickly located using the database search and sort functions. Relay entry is completed by entering the relay s nomenclature and serial number. Relays with identical model numbers can be entered sequentially using the like last button, with entry made complete by entering the serial number and nomenclature. With all relays entered in all racks at a site, the historical database is ready to accept test data. However, before testing can commence, the last prerequisite, site preparation, must be done Site preparation One time Activities Site preparation activities can be segregated into those which are one time activities and those which are required prior to each time testing is performed at a given site. One time activities include application of barcodes, and application of the connectivity blocks. Barcodes are applied to all relays for the purpose of identity verification, with barcodes also playing a role in the visual inspection process. Barcodes contain coded 9

10 information on circuit nomenclature, model number, and serial number, with the latter two items also printed in text on the barcode for user identification. With relay entry completed, the tester prints barcodes and the user applies them to each relay. With barcodes applied, the next step is application of the connectivity blocks. Connectivity blocks and their associated edge connectors or paddles as we will call them, constitute the connectivity devices which allow relays under test to be electrically connected to the tester. The B-1 relay version of the block shown here, is inserted behind the test nut on the 3E post. There is a version that can be used with B-2 relays, and shelf type relays as well. The special design of the block, along with its associated paddle allows the tester to be quickly inserted into the positive side of the coil circuit. When mounted on the 3E post, the block makes a separate connection with the negative or 1E side of the coil. Contacts internal to the block allow it to basically act as a receptacle to the paddle, and plugging the paddle into and removing from the block enables the tester to be quickly added and removed from the relay coil circuit. Blocks are designed to remain permanently in place on the plugboard if desired, or can be applied prior to and removed after each use. 10

11 Site preparation Activities Required at Each Use With connectivity blocks applied to all relays, the only activities remaining are those required each time testing is performed. Included in these activities are the insertion of the paddles, and verification of the relay s identity using the barcode reader. First, with tester software placed in the verification mode and node self tests performed, preparations are made complete by all paddles being inserted into the connectivity blocks. The purpose of verification is to make sure the tester uses proper manufacturer specification data for its tests, and that test data is applied to the correct relay. The hardware employed by this process includes a barcode reader connected into the serial port of the tester s laptop computer, numbered tags affixed to each paddle s connectivity cable, and correspondingly numbered buttons on the nodes. Verification is accomplished by the user first depressing a numbered button on the node, and then scanning the barcode on the relay connected to the correspondingly numbered paddle. When this is done, the computer correlates the node connectivity point and thus the tester software with the particular relay being scanned. In addition, as a double check, 11

12 the tester annunciates the scanned relay s serial number and nomenclature using synthesized voice, and at the same time, momentarily energizes that relay. In this fashion, the user is able to make positive verification that the tester is connected to the intended relay, and at the same time, make a visual inspection of the relay. Once this process repeated for each relay connected to each node, the verification process is complete. With verification completed, the last prerequisite for testing is disconnecting all sources of battery and commercial power within the instrument shelter under test. Deenergization of these energy sources is necessary due to the fact that during testing, the tester will energize numerous relays simultaneously. Since the shelter s circuitry may not be designed to accommodate simultaneous energization of certain relay combinations, it is necessary to disable all energy sources within the instrument shelter to prevent possible damage to relays, wiring or other hardware. 12

13 Testing With verification completed and energy busses disabled, testing can commence. When the command is given, each of the eight nodes begins sequential testing of the relays to which they are connected. Each node is connected to a maximum of eight relays, and testing is performed sequentially within the node until all relays connected thereto are tested. Testing in each node is concurrent with testing in all other nodes such that the tester is testing a maximum of eight relays at any one time. Time required for testing of a relay depends on the types of relays being tested, with slow acting relays requiring additional test time. Typically, each relay requires two minutes to test, which means testing of 64 relays requires 20 minutes or so to test. If slow acting relays are connected to the node, testing is slowed due to tester having to wait the slow acting time interval between incremental current or voltage changes. Testing normally requires no user intervention nor human interpretation of test results. Upon completion, the tester records the test data, and advises the user of any relays which test results fell outside acceptable limits. Once testing is complete, the user removes the paddles and restores energy busses as required. 13

14 Unique Features Which Add Flexibility to Testing Now I would like to step back a minute and briefly share with you some of the challenges we faced during development of the tester, while at the same time, discuss some of the features which were incorporated to make the tester more versatile and easy to use. During development, we had to address a few design issues whose means of resolution would dictate the degree to which the tester would be accepted by the users. Our closets were full of devices now gathering dust whose designers had good intentions but whose designs did not meet the needs of the end users. One central issue we faced was the design of the connectivity devices. We knew that we had to come up with a design which was easy to use while at the same time technically sound. Luckily, we realized early on that the best way to address this and other issues was to consult with those who would ultimately determine the success of the device, our field signal forces. After several meetings with the end users, we came up with a connectivity device which is easy to use by virtue of its quick disconnect design, and technically sound to the extent that it can be left permanently mounted in the instrument shelter if desired. During these meetings, there were even a few surprises in terms of 14

15 uncovering needs that were unanticipated in the early design. An example of this was the need for a means to clear up for train operations during the verification phase. At one of these meetings, it was pointed out that considering the time required to perform verification, there could be many locations where the volume of train movements would prevent us from performing the entire verification phase without having to clear up for trains. To address this issue, plug couplers were incorporated into the node design which allows the tester to be quickly added and removed from the relay coil circuits. Clearing up is accomplished by moving the plug coupler from the red colored or test receptacle to the green colored or run train receptacle on each node, an activity which can be done in a few minutes. Although this sounds simple, considerable complexity was added due to the requirement that the tester electronically verify the integrity of the cables to comply with disarragement considerations. Use of these colored plugs for clearing up during verification added tremendous flexibility to the use of the tester as it minimizes the duration of any necessary interruptions to the verification phase. 15

16 Prototype Performance Now that I have given you a brief overview of tester features and operational characteristics, I m sure by now you are anxious to hear how the tester has performed. Although we are still relatively early in our evaluation, the tester has performed well in testing we have done thus far. We took delivery of the prototype in July, and immediately set out to employ the system in testing of two mainline locations in the heart of Atlanta. With each location housing approximately 100 B-1 vital relays of various types, and passing an average of 50 train movements day, we felt these locations would be ideal for evaluating the testers attributes and features. I am happy to report that during these tests, the tester performed up to our expectations, encountering virtually no unanticipated problems during testing. Setup and verification phases went well, with the synthesized voice proving to be a great tool aiding in the process. Selection of these locations with heavy train traffic enabled thorough evaluation of the clearing up feature, which proved to be a very valuable tool in maximizing test time. Test results for all relays were stored on the tester s disk drive, and were printed out on NS s prescribed forms for our review. Overall, we encountered no 16

17 significant problems, with the tester meeting and in some areas exceeding our expectations. Summary I would now like to summarize where we have been with this project and what long term opportunities we see for this system. Although we believe we are off to a great start, we are mindful of the fact that we are at only the beginning of what will likely be a lengthy development process. We have much to do in our following through with our long term plan to incorporate all relays at all other locations into the tester s databases enabling testing at these sites. Although activities which lie ahead such as population of the databases seem very daunting at the moment, we can be encouraged by the knowledge that these will be one time activities for the railroad as a whole. We can be further inspired by the fact that as we add locations to the tester s database, we will be building a very useful systemwide inventory of relays used at our relay based interlockings and control points on Norfolk Southern. We are looking forward to these challenges, knowing that when we are successful in implementing our use of the tester, we will have made significant improvement in the accuracy and efficiency of the relay testing process on Norfolk Southern. Thank you for your attention, 17

18 and with that, I would like to entertain any questions you may have. Brian Sykes Norfolk Southern Corp. August 31,