5.3 Description of Function Codes 5.3.5 H codes (High performance functions)
Protection/Maintenance function (Mode selection)
H98 specifies whether to enable or disable automatic lowering of carrier frequency, input phase loss protection,
output phase loss protection, judgment threshold on the life of DC link bus capacitor, judgment on the life of DC link
bus capacitor, DC fan lock detection and braking transistor error detection by setting a bit combination.
Automatic lowering of carrier frequency (Bit 0)
This function should be used for critical machinery that requires keeping the inverter running. Even if a heat sink
overheat or overload occurs due to excessive load, abnormal surrounding temperature, or cooling system failure,
enabling this function lowers the carrier frequency to avoid tripping (OH1, OH3, OLU ). Note that enabling this
function results in increased motor noise.
Under sensorless vector control (synchronous motors), the automatic carrier frequency reduction function
does not work.
Input phase loss protection (lin ) (Bit 1)
This function detects the voltage unbalance between the phases and phase loss of 3-phase power supply. And an
alarm displays lin to stop the inverter when it detects.
In configurations where only a light load is driven or a DC reactor is connected, phase loss or line-to-line
voltage unbalance may not be detected because of the relatively small stress on the apparatus connected
to the main circuit.
Output phase loss protection (0pl: Output Phase Loss) (Bit 2)
Upon detection of output phase loss while the inverter is running, this feature stops the inverter and displays an
alarm 0pl.
Where a magnetic contactor is installed in the inverter output circuit, if the magnetic contactor goes OFF
during operation, all the phases will be lost. In such a case, this protection function does not work.
Judgment threshold on the life of DC link bus capacitor (Bit 3)
Bit 3 is used to select the threshold for judging the life of the DC link bus capacitor between the factory default
setting and a user-defined setting.
Before specifying a user-defined threshold, measure and confirm the reference level in advance.
( Function code H42)
Judgment on the life of DC link bus capacitor (Bit 4)
Whether the DC link bus capacitor has reached its life is judged by measuring the discharging time 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.
As a result, it may be mistakenly determined that the DC link bus capacitor has reached the end of its life. To avoid
such an error, you can disable the judgment based on the discharging time. (Even if it is disabled, the judgment
based on the “ON-time counting” while the voltage is applied to the DC link bus capacitor is performed.)
Refer to function code H42 for details.
Since load may fluctuate significantly in the cases described below, disable the judgment on the life during operation
even in user-defined setting mode. During periodical maintenance, either conduct the measurement with the
judgment enabled under appropriate conditions or conduct the measurement under the operating conditions
matching the actual ones.
• Auxiliary input for control power is used.
• An option card is used.
• Another inverter or equipment such as a PWM converter is connected to terminals of the DC link bus.
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