8 Fault Diagnosis
205
The motor speed is
unstable. The motor
speed fluctuates when
operating with a light
load.
The stall prevention level during
running is too low.
Because the Stall Prevention Level
during Running (n094) is too low, the
output current reaches the set level
and the speed drops.
Check if the Stall Prevention Level
during Running (n094) is set to an
appropriate value.
The load is too heavy.
If the load is too heavy, stall prevention
is activated, the output frequency is
stopped, and the acceleration time is
lengthened.
Reduce the load.
The carrier frequency is too
high.
If operating the motor with a light load,
a high carrier frequency may cause
the motor speed to fluctuate.
Decrease the carrier frequency (n080).
The V/f set value is too high for
a low-speed operation.
Because the set value for the V/f is too
high, over-excitation occurs at low
speeds.
Set the V/f (n011 to n017) according to
the load characteristics.
The maximum frequency (n011)
and maximum voltage frequen-
cy (n013) were incorrectly ad-
justed.
Example: To operate a 60-Hz motor at
40 Hz or less, the maximum frequency
and base frequency are set to 40 Hz.
Set the maximum frequency (n011)
and the maximum voltage frequency
(n013) according to the motor
specifications.
The Inverter is used for an
operation at 1.5 Hz or less.
Do not use the V7 Inverter for an
operation that runs at 1.5 Hz or less.
For an operation at 1.5 Hz or less, use
a different Inverter model.
The analog reference input is
unstable and has noise
interference.
Increase the set value for the filter time
constant (n062).
The LED of the Digital
Operator is unlit.
The power is not being
supplied.
The breaker or other component on
the power input side is not turned ON,
and the power is not being supplied.
Check if the power is being supplied.
Because the Digital Operator is not
correctly mounted, the display does
not appear.
Mount the Digital Operator correctly.
Short-circuit bar for ter1
and +2 is not connected.
Confirm that the short-circuit bar is
connected properly.
POWER charge indicator lamp
lights but the Digital Operator
does not give any display after
the power supply is turned ON.
Since the main circuit fuse is blown,
replace the Inverter.
Trouble
Cause
Corrective Actions
