Specifications
50
Prevents Motor from Stalling
Stall prevention selection during accel
L3-01
Stall prevention level during accel L3-02
Stall prevention limit during accel L3-03
Stall prevention selection during decel
L3-04
Stall prevention selection during run L3-05
Stall prevention level during run L3-06
（1）Stall prevention during acceleration
A function to prevent the motor from stalling when an
excessive load is applied to the motor during
acceleration or at rapid acceleration.
By setting L3-01 to 1, the motor stops acceleration and
holds the frequency if inverter output current exceeds
150 ％ (L3-02 set value) of inverter rated current.
When output current is 135 ％ (L3-02 set value
−15 ％
)
or less, acceleration starts again. Inverter rated output
current is regarded as 100 ％.
（2）Stall prevention during run
A function to prevent the motor from stalling reducing inverter
output frequency automatically when a transient overload
occurs while the motor is running at a constant speed.
By setting L3-05 to 1 or 2, the stall prevention during running
is enabled only in the V/f control mode. Deceleration starts
when inverter output current exceeds 160 ％ (L3-06 set value)
of inverter rated current during constant speed operation.
While output current exceeds 160 ％ (L3-06 set value), the
motor continues decelerating in the set deceleration time.
When inverter output current is 158 ％ (L3-06 set value −2 ％)
or less, the motor accelerates up to the set frequency in the set
acceleration time.
（3）Stall prevention during deceleration
A function to extend the deceleration time automatically
according to the size of main circuit DC voltage so that
overvoltage may not occur during deceleration. When a
braking resistor (optional) is used, be sure to set L3-04
to 0 or 3.
The following shows an example of the stall prevention
during deceleration when 1 is set to L3-04.
Stall prevention level during acceleration is automatically
reduced by the following equation in the constant output area
(output frequency ≧ max. voltage frequency E1-06).
However, in order to avoid this stall prevention level in
the constant output area from being reduced more
than necessary, use L3-03 to set the limit.
＊ Factory setting: L3-03 = 50 ％
Output Current
Motor Current
150% of Inverter
Rated Current
Output Frequency
Time
Time
＊
（L3-02）
（L3-02）−15 ％
＊ Output frequency is controlled so that stall status may
not be caused in the meantime.
Factory setting of L3-02 is 150 ％. By setting L3-01 to 0, the stall
prevention during acceleration will be disabled.
（ ）
Motor Current
160% of
Inverter Rated
Current
Output Frequency
Time
Time
＊1
＊2
＊2
（L3-06）
＊1 Frequency is reduced to prevent stalling in the meantime.
＊2 Unless output current is less than the set level, output
frequency is held at the minimum value.
Factory setting is 120 ％. By setting L3-05 to 0, the stall prevention
during running will be disabled.
（ ）
Time
Set Detection
Time
Output Frequency
Control Deceleration Time to Prevent
Overvoltage When Stall Prevention during
Deceleration Operates
L3-04 Setting
1
0
2
3
Stall Prevention during Deceleration
Disabled
Enabled (when braking resistor is mounted)
Enabled (Stops deceleration when main circuit
DC voltage is closed to the overvoltage level.
Starts deceleration again after recovery of voltage.)
Optimum adjustment (Decelerates in the shortest
time according to main circuit DC voltage.
Setting of deceleration time is disregarded.)
Stall prevention level during acceleration in constant output area
＝
Stall prevention level
during accel (L3-02)
Max. voltage frequency (E1-06)
× ―――――――――――
Output frequency