Inspection and test data analysis
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Understand the importance of collecting and analyzing battery data for preventive maintenance inspections. Learn to establish baselines, interpret test results, and identify potential issues through data analysis.
Inspection and test data analysis
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Presentation Transcript
Inspection and test data analysis John Polenz • 06/11/2017 • Supervisor Battery Technical Support - Vertiv
Data collection • Why collect the data if you aren’t going to do anything with it - • Except file it!
discussion • Preventive Maintenance Inspection Data • Consistent readings taken and recorded • Baselines established • Analysis of the data • Single report data analysis • Capacity Testing Data Analysis • Data recording • Unit and system data recording • Final analysis
Data analysis • So many times with battery analysis – • IT DEPENDS! • ASK Questions to help get the answers: • Was the battery recently cycled? • How long has the value been that way? • Is it recovering or getting worse? • Has anything changed that could impact the battery? • Have any corrective measures been attempted? • Have you verified system readings at the battery – not at the charger? *Additional Notes
PM Inspection DATA • Collecting Consistent readings! • Getting the right readings! • Importance of test equipment lead placement consistency • Different technicians will place test leads differently • Can negatively impact readings • Can impact trending • Misleading on actions to take *Additional Notes
Establish ohmic Baselines • Trending is best method *Additional Notes
Establish baselines • Establish Proper Baselines - Thresholds • Voltage • Internal Ohmic • Temperature • Ambient/unit • System Float • Unit float • Specific gravity *Additional Notes
Proper baselines Example: 7500 = 11250 (50% above first reading) 3750 = 5625 (50% above 6 months reading) Incorrect baselines can mask potential concerns! *Additional Notes
Specific gravity data analysis Can be hard to make correct determination *Additional Notes
Temperature swings *Additional Notes
Validation of data Float = 2.179 v/c Actual battery float requirement 2.25 v/c *Additional Notes
Validation of data • Investigation for: • Unit Float issues • Internal Resistance increase Actual float should be 535 VDC Nom. Float – 2.23 v/c Recorded – 2.246 v/c At the battery – 2.245 Exceeds manufacturer recommendations *Additional Notes
Take the Readings and move on • Sometimes it is plain • Sight! *Additional Notes
Don’t only record the data Low voltages Lower temperatures Low float setting *Additional Notes
Alarm triggers *Additional Notes
Single data set analysis • Improper threshold • It did not identify • Suspect units! • Quick visual look! The 3 units all exceed 50% above baseline using present data set *Additional Notes
Single data set analysis *Additional Notes
Contributing factors can be identified with analysis Voltage drop Over charge Under charge *Additional Notes
Lack of data for evaluation *Additional Notes
Capacity test Analysis • Capturing useable data • Capturing only system level vs. unit level • Voltage, temperature, current, time • Where the data is collected is important • UPS application – at the battery and at the UPS to aid in system design verification, *Additional Notes
Data analysis • Don’t assume the battery has failed - • Didn’t make time • Didn’t meet the ECV requirement • Cell/unit dropped out early • Example: • The following discharge testing results were observed: • On an 11 minute backup time rating, the batteries ran for approximately 16.5 minutes. • The batteries supplied over 100% capacity using the industry standard IEEE 1188, rate adjusted calculations. • At the 15 minute discharge point (before voltage drop-off) the lowest battery voltage was 9.871 • The test ran until the end cell voltage reached 1.60 volts/cell and the batteries supported an average load of 55.66kw for 16.5 minutes. *Additional Notes
Verifying report alarm thresholds Default software setting to 1.67v/c Changed to 1.50 v/c *Additional Notes
Test data • Data logging helps to make analysis easier and quicker *Additional Notes
Uniform test results *Additional Notes
Do not make battery performance assumptions till the data is analyzed • Analyze the data collected • Verify the load applied to UPS/battery • Verify published performance specification for the battery • Verify ECV cutoff setting • Verify temperature of the battery during the test • Calculate the battery capacity per IEEE 1188 *Additional Notes
Summary • Some data is better than none • The more data the better for evaluation • More data provides better trending • Better trending leads to better prevention to failures • Baselines need to be established properly • Data analysis can help to identify: • Charger issues • Environmental concerns • Failing battery • Voltage drop identification • Improper maintenance practice *Additional Notes