Fuji Electric FRENIC-HVAC User Manual page 675

The service life of the DC link bus capacitor can be judged by the "measurement of discharging time"
or "ON-time counting."
Measurement of discharging time of the DC link bus capacitor
- 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.
- The capacitance measuring conditions at shipment are drastically restricted, e.g., 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, revert those conditions to the factory default ones and
shut down the inverter. For the measuring procedure, see [ 1 ] given below.
- 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 ] on the next page. 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.
When the inverter uses an auxiliary control power input, the load conditions widely differ so
that the discharging time cannot be accurately measured. In this case, measuring of the
discharging time can be disabled with the function code H98 (Bit 4 = 0) for preventing
unintended measuring.
ON-time counting of DC link bus capacitor
- In a machine system where the inverter main power is rarely shut down, the inverter does not
measure the discharging time. For such an inverter, the ON-time counting is provided. The
ON-time counting result can be represented as "Elapsed time" (EneT) and "Time remaining before
the end of life" (RemT) as shown in Table 10.3, "On the LCD monitor" column.
[ 1 ] Measuring the capacitance of the DC link bus capacitor in comparison
with initial one at shipment
When bit 3 of H98 data is 0, the measuring procedure given below measures the capacitance of DC
link bus capacitor in comparison with initial one at shipment when the power is turned OFF. The
measuring result can be displayed on the keypad as a ratio (%) to the initial capacitance.
--------------------------------------- Capacitance measuring procedure ---------------------------------------
1) To ensure validity in the comparative measurement, revert the inverter condition back to the
default at factory shipment.
• Remove the option card (if already in use) from the inverter.
• In case another inverter is connected via the DC link bus to the P(+) and N(-) terminals of the
main circuit, disconnect the wires.
• Disconnect power wires for the auxiliary input to the control circuit (R0, T0).
• Turn OFF all the digital input signals on control circuit terminals [FWD], [REV], and [X1]
through [X7]. (Signals on terminals [EN1] and [EN2] can be either ON or OFF.)
• If an external frequency command potentiometer is connected to terminal [13] or [V2],
disconnect it.
• If an external apparatus is attached to terminal [PLC], disconnect it.
10.3 List of Periodic Replacement Parts
10-5