Hitachi WJ200 Series

6−21
Capacitor Life Curves
The DC bus inside the inverter uses a large capacitor as shown in the diagram below.
The capacitor handles high voltage and current as it smoothes the power for use by the
inverter. So, any degradation of the capacitor will affect the performance of the
inverter.
Capacitor life is reduced in higher ambient temperatures, as the graph below
demonstrates. Under the condition of average ambient temperature 40degC, 80% load,
24 hours operation, the lifetime is 10years. Be sure to keep the ambient temperature at
acceptable levels, and perform maintenance inspections on the fan, heat sink, and
other components. If the inverter is installed on a cabinet, the ambient temperature is
the temperature inside the cabinet.
Rectifier
Motor
Inverter Converter Internal
DC Bus
Power
Input
R/L1
S/L2
Variable-frequency Drive
T/L3
U/T1
V/T2
W/T3
A
mbient
temperature, °C
50
Years
Operation 24hours/day, 100% load
40
30
20
10
1 2 3 4 5 6 7 8 9 10
Operation 24hours/day, 80% load
Capacitor Life Curve
0