7-5
-2 Measuring the capacitance of the DC link bus capacitor (during power-off time under ordinary
operating condition)
If the measuring method for discharging condition of the DC link bus capacitor during a power-off
time under the ordinary operating condition at the end user’s installation is different from the initial
measuring method at the time of factory shipment, the capacitance of the DC link bus capacitors can
not be measured. Follow the procedure mentioned below when you measure the capacitance of the
DC link bus capacitors under the ordinary operating condition at the end user's installation.
------------------------------
Procedure for setting up measurement condition
------------------------------
1) Set function code H98 (Protection/maintenance function) to enable the user to specify the
judgment criteria for the service life of the DC link bus capacitor (Bit 3) (refer to function code
H98).
2) Place the inverter in stopped state.
3) Place the inverter in the state of power-off under ordinary operating conditions.
4) Set both function codes H42 (Capacitance of DC link bus capacitor) and H47 (Initial capacitance
of DC link bus capacitor) to "0000."
5) Switch OFF the inverter.
Measure the discharging time of the DC link bus capacitor and save the result in function code
H47 (Initial capacitance of DC link bus capacitor).
The condition under which the measurement has been conducted will be automatically
collected and saved.
During the measurement, " . . . . " appears on the LED monitor.
6) Switch ON the inverter again. Confirm that H42 (Capacitance of DC link bus capacitor) and H47
(Initial capacitance of DC link bus capacitor) hold right values. Move to Menu #5 "Maintenance
Information" and confirm that the relative capacitance (ratio to full capacitance) is 100%.
If the measurement has failed, "0001" is entered into both H42 and H47. Check
whether there has been any mistake in operation and conduct the measurement
again.
-----------------------------------------------------------------------------------------------------------------------------------
To change the settings back to the state at the time of factory shipment, set H47 (Initial capacitance
of DC link bus capacitor) to "0002"; the original values will be restored.
Hereafter, each time the inverter is switched OFF, the discharging time of the DC link bus capacitor is
automatically measured if the above condition is met.
The condition given above produces a rather large measurement error. If this mode gives
you a lifetime alarm, set H98 (Maintenance operation) back to the default setting (Bit 3
(Specify service life criteria for replacing the DC link bus capacitor) = 0) and conduct the
measurement under the condition at the time of factory shipment.
Electrolytic capacitors on the printed circuit boards
Move to Menu #5 "Maintenance Information" in Programming mode and check the cumulative run
time of the electrolytic capacitors on the printed circuit boards. This value is calculated from the
cumulative total number of hours a voltage has been applied on the electrolytic capacitor. The value
is displayed on the LED monitor in units of 1000 hours.
