Interval data overfl ow in 100W+ Series ERT modules WHITE PAPER

Transcription

1 Interval data overflow in W+ Series ERT modules Expanding traditional meter consumption data to better monitor usage and water loss. By Allen Rogers WHITE PAPER

2 W+ SERIES ERT MODULES Itron s W+ series ERT modules provide several valuable features that expand traditional meter consumption data into much greater detail. One such feature is the module s ability to store Interval Data. Interval Data is created by partitioning meter register consumption into specific time slots. The W+ ERT module automatically partitions and stores 0 days of consumption data into 0 hourly intervals. Once filled, each interval is continually updated with new usage information, and when requested, by the meter data collection application, such as: FDM, MV-RS, FCS, and FN the data is transferred in the form of hourly or daily totals that can then be used to generate customer usage reports encompassing one day of hourly intervals, 0 days of hourly intervals, or 0 days of daily intervals. The total consumption amounts that can be stored in each interval are based on the meter/register resolution, and are constrained to an absolute value for both positive and negative flow directions. The maximum amounts allowed for various meter resolutions are shown below. MAXIMUM POSITIVE INTERVAL LIMITS EXPRESSED IN GALLONS Meter 2.. / Positive Daily 00 2,.2,000 2,0. 0,000 2,00,. 00,000 2,,000,.,000, ,0,000 3,. 0,000,000 MAXIMUM NEGATIVE INTERVAL LIMITS EXPRESSED IN GALLONS Meter / Negative Daily , , -0, , -00,000,.,00 0 -,000,000,. -,,000

3 MAXIMUM POSITIVE INTERVAL LIMITS EXPRESSED IN CUBIC FEET Meter /0 / , 2,0 2,00 2,, ,.,. Converting Minute Cubic Feet to Gallons ,. 3,. 3,. Positive Daily 0 00,000 0,000 00,000,000,000 Converting Daily Cubic Feet to Gallons.,,0,00,,000,0,000 MAXIMUM NEGATIVE INTERVAL LIMITS EXPRESSED IN CUBIC FEET Meter /0 / ,000-0,000-00, ,. Converting Minute Cubic Feet to Gallons ,. -,. Notes:. U.S. Gallons and Cubic Feet are illustrated however limit amounts apply to all units of measure. 2. Per Minute interval data are for reference only and if exceeded do not activate the Overfl ow Flag. Negative Daily , -, -,00 Converting Daily Cubic Feet to Gallons ,2 -,2-2, -,2, AWWA MAX CONTINUOUS FLOW RATES BY SIZE For a recommend number of meter resolution dials please see the AWWA Max Flow Rates below. Size /", /" x 3/" 3/" " /2" 2" 3" 2" 3" " 2" 3" " " " Type GPM , ,000,00 Number of s maybe Low High Low High Low High Low High Low High

4 As indicated, the meter/register resolution has a direct effect on the amount of measured fl ow that can be stored for any one interval. As meter resolution changes by a multiple of ten, the interval bucket size also changes by a multiple of ten. Thus, programming an ERT module for less-count resolution increases the allowable interval size that can be stored, and as a consequence, reduces the likelihood of an Interval Overfl ow. When overfl ow occurs, the consumption value for that interval will be recorded as zero and further totalization of the accumulated daily value will be halted. The examples below are views of hourly and daily intervals as seen in FDM Tools. The graph lists various water consumption amounts from midnight through 3:00 p.m. on April, 20 with several intervals indicating zero usage. The graph label also indicates an overfl ow, and thus the recorded usage in at least one of the intervals has exceeded its maximum limit. The Daily version of the graph will also refl ect an overfl ow occurred. Each interval s detail must be examined in the Properties list to determine which hour overfl owed. This is highlighted in the example for the day shown in the chart. HOURLY CHART FOR APRIL TH The ERT module transfers the previous hour s data when an Extract Interval Data command is received. In the above chart, the 2:00 p.m. data was transferred at the :00 p.m. request. The transfer time is selectable within each meter data collection application. DAILY CHART FOR APRIL TH PROPERTIES In the highlighted example, the time of :00: Z represents an international dateline time that is fi ve hours greater than the U.S. CDT time for the hour segments shown in the chart. Times shown in the hourly chart example have been adjusted for this difference.

5 PREVENTING INTERVAL OVERFLOW Today, utilities and consumers are much more concerned about water conservation than they were just a few years ago. This has driven the need to create more sophisticated meters to capture and report smaller units of measurement. As a result, manufacturers are developing higher resolution meters and registers to better monitor usage and water loss. Several companies now offer nine-dial residential meters measuring in ths of a gallon. It s estimated the average household member uses between 0- gallons of water per day for a family of four, this would be approximately 320 to 00 gallons on an average day. As seen in the interval overfl ow tables, this amount of usage is within the daily limit for a meter measuring in ths of a gallon. However, additional sporadic usage, such as lawn watering, could easily exceed this value and lead to an interval overfl ow. To counter this limitation, Itron designed the W+ ERT module with an adjustable offset feature called Truncation. By defi nition, truncation is simply the process of right-shifting a specifi c number of the meter s consumption digits stored in the ERT module to eliminate and prevent displaying in the meter data collection application. As noted earlier, a change in truncation value produces a corresponding change in the interval overfl ow limit. Available truncation values and the effect each would have on a particular encoder meter or a nine-, eight-, or seven- dial pulser register are listed in the table to the right. Pulser registers, having resolutions lower than seven-dial, should be selected from the FC300 Endpoint Tools drop down list under Programming and not apply a truncation value higher than zero. To prevent interval data overfl ow, refer to the Maximum Interval Size charts and choose a truncation value that will encompass the maximum anticipated water usage during a single hour, plus 20 percent to account for unexpected events. Choosing too large of a value might prevent an interval overfl ow, but it would also unnecessarily limit the number of displayed meter/register digits. SIMILAR INFORMATION FROM OTHER METER DATA COLLECTION APPLICATIONS IS SHOWN BELOW. FCS MV-RS ENCODER OR,, AND DIAL PULSER METERS Truncation Values Number of Meter/ Register Digits ove r fl o w ove r fl o w Resulting Number of Digits Displayed in the Meter Application

6 BELOW ARE FC300SR SCREENSHOTS OF HOW TRUNCATION WOULD BE IMPLEMENTED FOR AN ENCODED REGISTER: Initiate Programming Register Selection Required Register Selected Default Truncation Value New Value Selected Programming Confi rmed Initial Consumption Value Value after Truncation

7 EFFECTS OF TRUNCATION ON OTHER ERT MODULE FUNCTIONS While the primary utilization of truncation is to prevent interval overfl ow in high resolution meters, other ERT module functions are also affected. Leak Detection Flag: This function is based on a comparison of the previous least signifi cant consumption digit to that of the current reading. A meter/register measuring in ths would set the leak fl ag with only a very small change in continuous fl ow. This would likely contribute to unintended repetitive leak fl ags, while truncating to a lower measurement resolution would minimize or eliminate those occurrences. Meter Right Sizing: Right Sizing is the process of analyzing water fl ow measurements within a selectable interval of time, over a specifi c number of days, to determine if the meter is sized appropriately for the amount of water being consumed. Because the comparison is based on using the reported consumption count, a change in truncation value above zero will reduce the resolution of the data being compared this could impact the decision about the correct meter size. For example, a meter with a resolution of one gallon and a truncation of zero might record several intervals of rightsizing data for a given time interval, whereas the same meter with a truncation value of three has a reading resolution of 0 gallons this amount of water fl ow might be too high for it to register data within the same time interval. Changing the time interval to a longer period might provide suffi cient consumption data to determine appropriate rightsizing. Reverse Flow: A tamper fl ag that is based on a comparison of the current least signifi cant meter consumption digit to the previous one. As in the above example, if the current least signifi cant digit s consumption value is one gallon, with a truncation of zero, and the truncation value changes to three, then reverse fl ow would now be based on a change of 0 gallons as a consequence, the reverse fl ag might never set, even though the meter s actual consumption value in gallons would have set the fl ag. Meter Quiet Mode: This is a special factory-ship mode that allows the ERT module to automatically switch to Normal Mode after detecting a small change in consumption. Typically, a change of plus or minus one count would allow the transition to occur. However, if a truncation value greater than zero is programmed, the count change needed to implement the Normal Mode switchover would increase accordingly. WHEN IS IT APPRPPRIATE TO USE THE TRUNCATION FUNCTION? Truncation is a valuable option to consider in reducing interval overfl ow. However, truncation affects other ERT module functions, and the decision for its use should be weighed against those additional changes and the impact they will have on your overall system performance needs. Join us in creating a more resourceful world. To learn more visit itron.com While Itron strives to make the content of its marketing materials as timely and accurate as possible, Itron makes no claims, promises, or guarantees about the accuracy, completeness, or adequacy of, and expressly disclaims liability for errors and omissions in, such materials. No warranty of any kind, implied, expressed, or statutory, including but not limited to the warranties of non-infringement of third party rights, title, merchantability, and fi tness for a particular purpose, is given with respect to the content of these marketing materials. Copyright 20 Itron. All rights reserved. 3WP-0 2/ CORPORATE HQ 2 North Molter Road Liberty Lake, WA 0 USA Phone: Fax:.0..33