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8-3
(1) Remove any optional cards from the inverter. Also disconnect the DC bus connections to the
main circuit P(+) and N(-) terminals from the braking unit or other inverters if connected. The
existing power-factor correcting reactor (DC reactor) need not be disconnected.
A power supply introduced to the auxiliary input terminals (R0, T0) that provides control power
should be isolated.
(2) Disable all the digital inputs (FWD, REV, X1-X9) on the control terminals. Also disconnect
RS-485 communication if used.
Turn on the main power supply. Confirm that the cooling fan is rotating and that the inverter is not
operating. (There is no problem if the "OH2 External thermal relay tripped" trip function is
activated due to the digital input terminal setting off.)
(3) Turn the main power off.
(4) Turn on the main power again after verifying that the charge lamp is completely off.
(5) Open the maintenance information on the keypad panel and confirm the capacitance values of
the built-in capacitors.
2) Life expectancy of the control PC board
The actual capacitance of a capacitor is not measured in this case. However, the integrated
operating hours of the control power supply multiplied by the life expectancy coefficient defined
by the temperature inside the inverter will be displayed. Hence, the hours displayed may not
agree with the actual operating hours depending on the operational environment.
Since the integrated hours are counted by unit hours, power input for less than one hour will be
disregarded.
3) Life expectancy of cooling fan
The integrated operating hours of the cooling fan are displayed. Since the integrated hours
are counted by unit hours, power input for less than one hour will be disregarded.
The displayed value should be considered as a rough estimate because the actual life of a
cooling fan is influenced significantly by the temperature.
Table 8-2-2 Rough estimate of life expectancy using maintenance information
Parts Level of judgment
Capacitor in main circuit 85% or less of the initial value
Electrolytic capacitor on
control PC board
61,000 hours
Cooling fan 40,000 hours (5HP or less), 25,000 hours (Over 7.5HP) (*1)
*1 Estimated life expectancy of a ventilation-fan at inverter ambient temperature of 40°C (104°F)