7-3
Chap. 7 MAINTENANCE AND INSPECTION
7.3.1 Judgment on service life
The inverter has the life prediction function for some parts which measures the discharging time or counts the voltage applied
time, etc. The function allows you to monitor the current lifetime state on the LED monitor and judge whether those parts are
approaching the end of their service life.
The life prediction function can also issue early warning signals if the life time alarm command LIFE is assigned to any of the
digital output terminals. (Refer to "[ 3 ] Early warning of lifetime alarm" later in this section.)
Table 7.3 lists the parts whose service life can be predicted and details the life prediction function. The predicted values should
be used only as a guide since the actual service life is influenced by the surrounding temperature and other usage environments.
Table 7.3 Life Prediction
Object of life
prediction
Prediction function End-of-life criteria Prediction timing On the LED monitor
85% or lower of the initial
capacitance at shipment
(See "[ 1 ] Measuring the
capacitance of DC link bus
capacitor in comparison with
initial one at shipment" on page
7-4.)
At periodic
inspection
(H98: Bit 3 = 0)
5_05
(Capacitance)
Measurement of discharging time
Measures the discharging time of
the DC link bus capacitor when
the main power is shut down and
calculates the capacitance.
85% or lower of the reference
capacitance under ordinary
operating conditions at the user
site
(See "[ 2 ] Measuring the
capacitance of DC link bus
capacitor under ordinary
operating conditions" on page
7-5.)
During ordinary
operation
(H98: Bit 3 = 1)
5_05
(Capacitance)
DC link bus
capacitor
ON-time counting
Counts the time elapsed when the
voltage is applied to the DC link
bus capacitor, while correcting it
according to the capacitance
measured above.
Exceeding 87,600 hours
(10 years)
During ordinary
operation
5_26
(Elapsed time)
5_27
(Time remaining
before the end of life)
Electrolytic
capacitors on
printed circuit
boards
Counts the time elapsed when the
voltage is applied to the
capacitors, while correcting it
according to the surrounding
temperature.
Exceeding 87,600 hours
(10 years)
During ordinary
operation
5_06
(Cumulative run time
Cooling fans Counts the run time of the cooling
fans.
Exceeding 87,600 hours
(10 years)
During ordinary
operation
5_07
(Cumulative run time
Notes for the judgment on the service life of the DC link bus capacitor
The service life of the DC link bus capacitor can be judged by the "measurement of discharging time" (
c to f
) or "ON-time
counting" (
g
)
.
c
The discharging time of the DC link bus capacitor depends largely on the inverter's internal load conditions, e.g. options
attached or ON/OFF of digital I/O signals. If actual load conditions are so different from the ones at which the
initial/reference capacitance is measured that the measurement result falls out of the accuracy level required, then the
inverter does not perform measuring.
d
The capacitance measuring conditions at shipment are extremely restricted--e.g., with the remote keypad mounted and all
input terminals being OFF--in order to stabilize the load and measure the capacitance accurately. Those conditions are,
therefore, different from the actual operating conditions in almost all cases. If the actual operating conditions are the same
as those at shipment, shutting down the inverter power automatically measures the discharging time; however, if they are
different, no automatic measurement is performed. To perform it, put those conditions back to the factory default ones and
shut down the inverter. For the measuring procedure, see [ 1 ] given on the next page.
e
To measure the capacitance of the DC link bus capacitor under ordinary operating conditions when the power is turned
OFF, it is necessary to set up the load conditions for ordinary operation and measure the reference capacitance (initial
setting) when the inverter is introduced. For the reference capacitance setup procedure, see [ 2 ] given on page 7-5.
Performing the setup procedure automatically detects and saves the measuring conditions of the DC link bus capacitor.
Setting bit 3 of H98 data to 0 restores the inverter to the measurement in comparison with the initial capacitance measured
at shipment.
f
If the multi-function keypad is mounted, the inverter does not measure the discharging time automatically since the
inverter's conditions are different from the ones applied at shipment. It is, therefore, necessary to perform the setup
procedure mentioned in
e
above to enable the measurement under ordinary operating conditions.
To make an accurate judgment on the service life of the DC ink bus capacitor (accurate measurement of the capacitance),
select the judgment procedure according to the keypad type and the measuring conditions, following the flowchart given on
the next page.
CTi Automation - Phone: 800.894.0412 - Fax: 208.368.0415 - Web: www.ctiautomation.net - Email: info@ctiautomation.net
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