What can go wrong with a capacity test

download report

Transcript What can go wrong with a capacity test

John Polenz
Emerson Network Power
Liebert Services
Prior
to the test
During the test
After the test
Just kill the input and let’er run till she drops
and see how long it runs!
 Do
you use IEEE 1188, 450, &1106 as a
reference and guide?
 Do you know what the Battery Manufacturer
requirements are?
 Most
require initial/equalize charge – Really?
 72 hour float after equalize and prior to
testing


Cool down?
Dissipation of Gas build up on plates
 Initial/equalize
Timelines for VLA can be
extensive

150 hrs vs 24 hrs
 Ensuring

Full state of Charge
Construction events
 Constant
current testing vs constant power
 System
functionality vs Battery capacity
 More than not with UPS applications

Primarily acceptance testing
 No
planning or knowledge of battery
manufacturers requirements for capacity
testing


IOM not reviewed
Timeline issues
 Test
requirements
What is the actual sizing of the battery?
You mean I have to know the sizing for the battery?
KVA/KW load
 Inverter efficiencies
 Power factor
 Aging factor
 Temperature
 Number of cells/string
 Put the info into the formulasKVA Rating X Power Factor = KW Load
KW Load ÷ Inverter Efficiency = KW Battery Load
KW Battery Load ÷ # of Cells = W/Cell requirement

This is the “WHY” you want to test as a system!
 What

prepping?
The battery has been on float for a couple of
days
 You
discover that the battery has been
discharged multiple times due to SAT
requirements
 UPS voltage setting not verified prior to the
test
 UPS End Cell Voltage not verified or known
 Voltage drop in system

Battery and UPS to battery connections
 Temperature
is not considered as an issue
 Not prepped as required by the manufacturer




Not enough time in schedule
Didn’t have the information
Didn’t realize the requirements existed
Assumed just a 15 minute battery

No data recording


Data logging equipment issues
Inadequate data collected
System data only at the UPS
 At the beginning and at the end of the test


IR testing -Thermal concerns –when do we stop
the test?

Connection concerns


High resistance –high temperatures
Battery temperature

No parameters established
Cell reversal
 Equipment malfunctions

 It


didn’t make the time!
The system only ran for 6.5 minutes instead of 8
minutes
Battery temperature was found to be 62F
 Not



System vs. individual cell/unit ECV
Some units fell below specified ECV
Test ran for 15 minutes, but battery was sized for
10 minutes?
 Not

all the units met the ECV requirement!
tested at 77F(25C)
Temperature was at 62F
 Didn’t
ensure battery was at FSOC
 Didn’t
perform initial charge
 Didn’t perform initial charge properly
 Didn’t provide 72hr float prior to testing
 No monitoring for the test – only system level
monitoring

No data to prove or disprove
 Metering
not calibrated
 Only using UPS meters to collect system data
 Time
not monitored during the test
 Not every cell/unit met the ECV cutoff –

1.60-1.67 v/c
 Didn’t
make time!
 No final data review
 No calculations to verify test results

Are not familiar with IEEE rate adjusted or time
adjusted calculations
 No
one knows actual sizing of the battery
 Test stopped before it should be


Wrong ECV
Wrong time
 No
agreement on “stop test” criteria
 Lack

of prior planning
When to stop the test is not known
 Improper


Wrong size (voltage)load bank
Can cause a fire
 Issues




equipment used
with equipment
Out of calibration
Doesn't measure properly
Doesn’t record good data to be reviewed
Doesn’t record the data at all
 Test
Equipment failures
 Facility damage
 Misinterpretation of battery capacity
 Delays in commissioning
 Additional costs incurred

Expect tests to be run until the battery makes
the numbers!
 Customer
dissatisfaction
 Battery failed
 Make

Alarms customer!
 Plan

the testing
Agreement on:




Testing parameters
Testing procedures
Capacity calculations/analysis process
Timelines
 Know



no Judgment calls prior to data analysis
the battery parameters
Sizing
Temperature impact
ECV
 Collect



proper data
System level
Cell/unit level
The more the better!
 Analyze


the data collected
IEEE 1188, 450, 1106
Rate adjusted method
 Consult
the battery manufacturer’s if there
are questions/concerns