Hitachi LH1 Series

5-4
Chapter 5
Troubleshooting
Event ▶
Estimated cause ▶
Corrective action
Motor speed does
not increase
・Frequency source is low
・If output current is high, the overload restriction function
[bA122] lowers the frequency. To increase the acceleration
time [AC120], it is necessary to suppress the current increase..
・Overload restriction function is
in use
・Increase the frequency source or cancel any other high
priority frequency command such as jogging or multi-speed.
・The upper limit [bA102] setting may be low, and it should
be increased. The frequency limiting does not make use of
the maximum frequency, but the upper limit function.
・Frequency is being limited
・Acceleration time is long
・Acceleration time [AC120] setting is long, so will accelerate
really slowly. Shorten gradually the acceleration time.
Output frequency
is unstable
・Check for the motor basic parameters.
・Several parameters are not
adequately set
・Review the power capacity of both the inverter and motor.
・Big variation in the load
・To keep to a minimum the supply fluctuations, by using an
optional AC reactor, DC choke or and input filter,
improvement is possible.
・Supply voltage fluctuates
No torque
・Can switch in [AA121] to torque boost, sensorless vector
control, … etc.
・V/f control is in use
・If the torque in the regenerative operation is not enough,
you can use a braking resistor or regenerative braking unit.
・It is being used for lift down
application
・Review the capacity of both the inverter and motor.
・Very heavy load
In operation the
circuit breaker gets
activated
・Lower the carrier frequency [bb101]
・Increase the current sensitivity of the circuit breaker, or
replace the sensitivity current sensor/part.
・Large leakage current
Noise interferes
with the TVs and
radios nearby the
inverter
・If possible, separate the wiring from the TV and radio
・Put a zero-phase reactor either in the main supply input or
in the output.
・Irradiated noise from the
inverter