5-73
Judgment on the life of DC link bus capacitors
Whether the DC link bus capacitor (reservoir capacitor) has reached its life is determined by
measuring the length of time for discharging after power off. The discharging time is determined
by the capacitance of the DC link bus capacitor and the load inside the inverter. Therefore, if the
load inside the inverter fluctuates significantly, the discharging time cannot be accurately
measured, and as a result, it may be mistakenly determined that the life has been reached. To
avoid such an error, you can disable the judgment on the life of the DC link bus capacitor.
Load may vary significantly in the following cases. Disable the judgment on the life during
operation, and either conduct the measurement with the judgment enabled under appropriate
conditions during periodical maintenance or conduct the measurement under the actual use
conditions.
• Auxiliary input for control power is used
• An option card or multi-function keypad is used
• Another inverter or equipment such as a PWM converter is connected to the terminals of the
DC link bus.
For details, refer to Chapter 7 "MAINTENANCE AND INSPECTION."
Detection of DC fan lock
(208 V : 50HP or above, 460 V : 75HP or above)
An inverter of 50HP or above (208 V), or of 75HP or above (460 V) is equipped with the internal
air circulation DC fan. When the inverter detects that the DC fan is locked by a failure or other
cause, you can select either continuing the inverter operation or entering into alarm state.
Entering alarm state: The inverter issues the alarm
0h1
and coasts to stop the motor.
Continuing operation: The inverter does not enter the alarm mode, and continues operation of the
motor.
Note that, however, the inverter turns on (OH) and (LIFE) signals on the transistor output
terminals whenever the DC fan lock is detected regardless your selection.
If ON/OFF control of the cooling fan is enabled (H06 = 1), the cooling fan may stop
depending on operating condition of the inverter. In this case, the DC fan lock detection
feature is considered normal (e.g.; the cooling fan is normally stopped by the stop fan
command.) so that the inverter may turn off the (LIFE) or (OH) signal output, or enable to
cancel the
0h1
alarm, even if the internal air circulation DC fan is locked due to a failure
etc. (When you start the inverter in this state, it automatically issues the run fan
command, then the inverter detects the DC fan lock state, and turn on the (LIFE) or (OH)
output or enters the
0h1
alarm state.)
Note that, operating the inverter under the condition that the DC fan is locked for long time may
shorten the life of electrolytic capacitors on the control PCB due to local high temperature inside
the inverter. Be sure to check with the (LIFE) signal etc., and replace the broken fan as soon as
possible.
To set data of the function code H98, assign functions to each bit (total 6 bits) and set it in decimal
format. The table below lists functions assigned to each bit.
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