7.3 List of Periodic Replacement Parts
7-5
Chapter 7 MAINTENANCE AND INSPECTION
Measurement of discharging time
• 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, put those conditions back to the factory default ones and shut down the inverter. Then automatic
measurement is carried out (refer to the measuring procedure 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 at "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
• 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 time elapsed when the voltage is applied to the DC link
bus capacitor is counted (ON-time counting) for judging the remaining lifetime. (The ON-time counting
result can be represented as "elapsed time"(
5_26
) and as "time remaining before the end of life"
(
5_27
), as shown in the "LED monitor indication" section in Table 7.3-2.)
(1) Measuring the capacitance of DC link bus capacitor in comparison with initial one at shipment
The measuring procedure given below measures the capacitance of DC link bus capacitor, and judges and
indicates the remaining lifetime. 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, put the condition of the inverter back to the state at
factory shipment.
• Remove the option card (if already in use) from the inverter.
• In the case another inverter is connected via the DC link bus to the P(+) and N(-) terminals of the
main circuit, disconnect the wires. You do not need to disconnect a DC reactor (optional), if any.
• Disconnect power wires for the auxiliary input to the control circuit (R0, T0).
• If the remote keypad was replaced with an optional multi-function keypad after purchase, return it to
the remote keypad.
• Turn OFF all the digital input signals fed to terminals [FWD], [REV], and [X1] through [X9] of the
control circuit.
To Next Page
Loading...
