Tracking Signal Fluctuations with a Graphical MultiMeter
Contents
1. 30 00 74 53 mAAC j i 10 14 58 00 45 00 High Low 86 37 nAAC 00 45 00 74 23 mAAC i 10 29 59 01 00 00 High Low 86 17 BAAC 01 00 00 73 04 mAAc i 10 44 59 61 15 00 High Low 78 36 mAAC 01 15 00 72 43 mAAC i 10 59 59 61 30 00 High Low 76 82 mAAC 01 30 00 72 48 mAAC i 23 15 00 61 45 00 High Low 77 11 AAC 01 45 00 72 63 MAAC 12 30 00 62 00 00 High Low 85 12 BAAC 02 00 00 72 31 mAAC The printer prints a line of ASCII text for each plotted data point except when High Low data type is selected The High Low data type selection causes two lines of text to be printed for each plot point The first printed line is the high reading and the second line is the low reading To stop the printing of trend data press the Enable RS232 1 softkey again Figure 4 contains a sample of the trend data collected on a PC for the load center example used in this application Each line of the printout contains the real time PC clock the data was output the elapsed time the trend data type the maximum reading and the minimum reading The elapsed time is the accumulated time since starting the trend mode While sending ohms trend data out the GMM s serial port with the glitch mode enabled the text Discon Discontinu ity appears in a column between the trend type label Sample Average or High Low and the ohms value to indicate an ohms glitch The trend data captured with the FlukeView software can be imported into a spreadsheet for further analysis2. brought into a report or archived for future reference Printing Screens The plotted graph along with other display data can be printed directly to a printer or sent to a PC for inclusion with reports To print the display first review the Printing section of the 860 Users Manual which describes how to properly setup the printer and connect it to the GMM To print a screen on a properly connected printer 1 Press the PRINT SAVE key 2 Press the Print 3 softkey To stop printing press the Stop Print 3 softkey To import GMM screens into a PC use the FlukeView 860 software on a compatible PC The screens used in this application note were imported from an 865 using the FlukeView 860 software Refer to the SW860 FlukeView Software Users Manual for proper setup and operation Tracking Long Term Trends Setting up the GMM to track data for longer than 6 to 10 hours requires the use of the battery eliminator Typically the NiCd battery pack provides up to 10 hours of operation while a set of alkaline batteries may only last 6 hours By connecting your GMM to an appropriate power source through the battery eliminator you can collect data indefinitely Although the maximum GMM display is 30 hours a GMM downloading trend data to a PC could go for a much longer period of time Other Trend Applications Using the GMM with compatible Fluke accessories provides a variety of measurement capabilities beyond those contained in the mete
3. the MIN MAX mode was started Using the data from Figure 3 and a start time of 9 30 A M the minimum load was at 4 08 P M and the maximum load occurred at 6 31 A M 8402 mAAC MAX 16256 mac 21 01 03 AVG 75 74 nec 24 05 59 MIN 64 13 nac 05 38 57 Trend SAA MIN HAX Min Max OFF Restart Pause Exit Figure 3 MIN MAX Reading Tracking Continuity Glitches Selecting trend view in the Ohms function causes an additional softkey selection to appear over softkey no 4 Normal Glitch When in Normal the TrendGraph mode operates as explained above The Glitch selection adds a narrow band under the horizontal axis of the plot area In this glitch area of the plot vertical marks indicate where fast occurring changes in continuity occur Each GMM resistance range has a predetermined trip point that enables or disables the continuity beeper Table 1 lists the trip values for the 860 Series Graphical Multimeter Range Beeper On Beeper Off 300 Ohm lt 32 Ohm gt 136 Ohm 3kOhm lt 2120hm 5725 Ohm 30kOhm lt 1 6kOhm gt 4 8 kOhm 300 kOhm lt 15 4 kOhm gt 45 5 kOhm 3MOhm lt 153 kOhm gt 459 kOhm 30 MOhm lt 66 kOhm gt 194 kOhm Table 1 Continuity Trip Points With glitch mode enabled these same trip points are used to detect a continuity glitch The GMM places a vertical bar in the glitch area of the plot when the measured resistance goes from high to low or low to high across the trip point in less than 25 mi
4. Tracking Signal Fluctuations with a Graphical MultiMeter Introduction The 860 Series of Graphical MultiMeters GMM are state of the art multimeters that use graphical features to display measurement information One of those graphical features is TrendGraph TrendGraph plots measurement data over a selected time period The GMM can plot AC and DC voltage amplitude AC and DC current amplitude AC signal frequency and ohms Not only does the GMM display the plotted data but it outputs data to a printer or a personal computer as well The TrendGraph feature is useful whenever you want to monitor a GMM measurement over time Some typical monitoring applications are line voltage for sags and surges load center current battery charging and discharging cycles temperature changes frequency changes and intermittent continuity to name just a few This application note describes the TrendGraph feature and how to use it in actual measurement situations Setting Up the GMM Connect the GMM to the circuit and select the appropriate function for the measurement desired For example plotting the current drawn from one phase of an outlet load center requires an AC current probe The current probe steps down the load center current to a range within the GMM s measurement capabilities Connect the current probe s output between the GMM s COM and mA mA jacks Select the mA mA function and clamp the current probe around the load center wi
5. is action makes the graph appear to walk toward the left just like chart paper coming out of a strip chart recorder The data point shifted off the end of the graph is gone from the GMM s memory The value measured by the GMM is represented by the placement of the plot point on the graph s vertical axis The relative time of the measurement is represented on the horizontal axis The time an event occurred can only be related to other plot points on the graph Figure 1 shows a typical TrendGraph display 12000 1O0sec Div 130V VAC Isec Sample 2 min ie Trend 307 AUTO nable ime Tine trend Mestart RS232 L ger Shorter Type Trend Figure 1 Typical TrendGraph Plot Figure 2 is an actual example of a High Low trend plot of current drawn from a load center supplying power to a building s AC outlets MINHA 8405 1SOminDi a mAAC 1SminAtign Low 36 hours Trend Saga me t Tie Trend yes tary Longer iShorter Tue i Trend Figure 2 Load Center Trend Plot While plotting the load center s current the GMM s MIN MAX mode was also running in the background The timer information displayed next to the minimum and maximum values is used to determine the actual time of day the load center s minimum and maximum load occurred Figure 3 shows the MIN MAX data taken during the load center current plotting To calculate the time of day the two events occurred simply add the timer values to the time of day
6. is based 2 Press the PRINT SAVE key 3 Press the Recall 2 softkey 4 Move the highlight bar to the desired configuration by pressing the down 1 or up 2 softkey 5 Press the Load Config 4 softkey The Load Config softkey will only appear when the function selected by the rotary switch is compatible with the highlighted configuration Outputing Trend Data If more trend data detail is required the GMM s optically isolated RS 232 interface sends out actual measurement data to a printer or a PC When connected to a PC running FlukeView 860 software all data for each plot point is sent to the PC and recorded in memory The amount of data collected is only limited by the amount of available memory in the PC You can create printed hard copy listings of the trend data as follows 1 Connect a compatible printer to the GMM s RS 232 serial port as explained in the PC and Printers Connection section of the 860 Users Manual 2 Rotate the rotary switch to Set Up and set the GMM s printer type baud rate and parity to match the printer 3 With the GMM in Trend Mode press the Enable RS232 1 softkey Started Gathering Trend on 08 09 95 at 09 30 14 Stopped Gathering Trend on 08 10 95 at 09 30 56 Records Gathered 96 i Time Tine Data ee ce ce ee ee ee ee ee ee a e a a a o a a a a a a a a a e H 09 47 57 00 15 00 High Low 75 67 mAAC 00 15 05 73 89 mAAC i i 09 59 58 0 30 00 High Low 80 28 mAAC 00
7. liseconds Gradual changes through the trip points will not trigger the glitch indication Storing Screens and Configurations The TrendGraph and other display data can be stored printed or downloaded to a PC To store displayed information 867B only 1 Press the PRINT SAVE key 2 Press the Save Screen 1 softkey 3 Press the up 2 or down 3 softkey to move the highlight bar to one of the three screen storage locations 4 Press the Save 3 softkey The label used for the stored screen is a combination of the display mode Meter Combo View etc and the measured value Storing the screen only captures an image of what is within the confines of the display This is analogous to placing a camera on the display and snapping a picture To download the GMM screen data to a PC you will need the FlukeView 860 software Refer to the software user s manual for setup connection and downloading instructions To speed up the setting of the range trend type and time interval you can save the GMM configuration settings as follows 1 Press the PRINT SAVE key 2 Press the Save Config 4 softkey 3 Move the highlight bar to one of the seven configuration memories by pressing the down 1 or up 2 arrows 4 Press the Save 3 softkey 5 Press Exit 5 to return to the selected display mode To recall the configuration 1 Ensure that the rotary function switch is set to the function on which the configuration
8. r alone You can measure temperature pressure vacuum and AC power with the appropriate accessory Plotting temperature is possible by using either the 80T 150U Universal Temperature Probe 80TK Thermocouple Module or 80T IR Infrared Temperature Probe Each of these accessories fits a specific range and application environment criteria Plotting pressure and vacuum measurements is possible using the PV350 Digital Pressure Vacuum Module The PV350 displays results in English psig or inches Hg or metric kPa or cm Hg units The 80i kW Current kW Power Probe converts a combined measurement of volts and current into one kilowatt reading The Power Probe works on both AC and DC current measuring up to 330 kilowatts Summary Tracking signal fluctuations over time is easy with the TrendGraph feature TrendGraph is just one of many functions built into the 860 Series Graphical MultiMeters This six in one meter offers versatility and accuracy in tracking down complex problems in electrical and electronic circuits There are two models in the 860 Series the economical 863 and the full featured 867B Both of the models will make the measurements mentioned in this application note Contact your nearest Fluke representative for further information
9. re or bus bar The range and wavescale settings determine the scale of the graph s vertical axis Changing the wavescale adjusts the vertical scale to 25 50 or 100 of the range setting Adjust these controls for an on scale reading before setting up the trend mode Selecting the Trend Mode Trend is one of four GMM display modes To select the Trend mode 1 Press the DISPLAY MODE key 2 Press the Trend 4 softkey The plot graph appears in the window display area of the GMM In addition the five blue softkeys change to trend control functions Setting the Time I nterval The time between plot points time interval is adjustable from 1 second to 15 minutes This range makes it possible to display from 2 minutes 120 seconds to 30 hours across the entire graph For reference the horizontal axis has a hash mark or division every tenth time interval The Time Longer 2 and Time Shorter 3 softkeys adjust the time between each plot point There are 12 time interval settings in trend mode 1 2 5 10 15 30 45 seconds and 1 2 5 10 15 minutes Each time change clears and restarts the trend graph The 1 second time interval is not available when plotting frequency To the right of the graph the GMM displays the time per sample and the total graph time Above the graph as time division the time between hash marks 10 time intervals is displayed Setting Trend Type The plotted data points can represent one of three da
10. ta types sampled average or high low The Trend Type softkey 4 selects the data type The Sampled data type selection places a data point on the graph that represents the latest measurement taken by the GMM In other words the plotted data point is equal to the digital reading displayed at that moment The Average data type selection places a data point on the graph that represents the average of all measurements taken by the GMM since the previous data point Although this measurement may seem identical to the average reading used in the GMM s MIN MAX mode it is different in that the readings are averaged for each plotted data point instead of over the entire trend time The High Low data type places a vertical bar on the plot for every data point The bottom end of the vertical bar represents the lowest sample measured since the previous data point and the top end represents the highest sample The GMM clears the minimum and maximum data registers after each data point plot and uses a new set of MIN MAX data for the next data point This selection captures any large changes that occur during the time interval Using the GMM Displaying a TrendGraph In TrendGraph mode the GMM plots 120 points of measurement data on a graph in the window display area of the GMM When a measurement is added the plot points already on the graph shift one plot point to the left and the GMM places the new measurement at the right end of the graph Th
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