12.7 L: Protection Functions
330 YASKAWA SIEPYEULA5001C LA500 Technical Manual
◆ L3: Stall Prevention
L3 parameters set the Stall Prevention function and overvoltage suppression function.
■ Stall Prevention
If the load is too heavy or the acceleration and deceleration times are too short, the motor can slip too much
because it cannot work at the same rate as the frequency reference. If the motor stalls during acceleration, current
increases as the slip increases to cause an oC [Overcurrent], oL2 [Drive Overload], or oL1 [Motor Overload] and
the drive will stop. If the motor stalls during deceleration, too much regenerative power will flow back into the
DC bus capacitors, and cause the drive to fault out from ov [Overvoltage] and the drive will stop.
The stall prevention function will let the motor get to the set speed without stalling and it is not necessary for you
to change the acceleration or deceleration time settings. You can set a separate stall prevention functions for
acceleration, operating at constant speeds, and deceleration.
■ L3-01: Stall Prevention during Accel
No.
(Hex.)
Name Description
Default
(Range)
L3-01
(048F)
Expert
Stall Prevention during
Accel
Sets the method of the Stall Prevention During Acceleration.
1
(0 - 1)
Stall prevention during acceleration prevents the stalling and stopping of motors when the drive detects oC
[Overcurrent], oL2 [Drive Overloaded], or oL1 [Motor Overload] when you apply a large load during
acceleration or when you set sudden acceleration times related to load inertia.
0 : Disable
The Stall Prevention function does not operate during acceleration, and acceleration occurs for the set acceleration
time. If the acceleration time is too short, the motor does not fully accelerate during the set time, which causes the
drive to detect oL1 or oL2 and the motor to stop.
1 : Enabled
Enables the Stall Prevention During Acceleration function. Operation is different for different control methods.
• V/f Control, Open Loop Vector Control, or EZ Open Loop Vector Control
When the output current is more than the value set in L3-02 [Stall Prevent Level during Accel], the drive stops
acceleration. The drive stops deceleration when the output current is less than L3-02 - 15%. The Stall
Prevention function level automatically decreases for constant output ranges.
Figure 12.28 Stall Prevention During Acceleration when Using Induction Motors
• Open Loop Vector Control for PM
When the output current is more than L3-02, the drive stops acceleration. When the time set in L3-27 [Stall
Prevention Detection Time] is expired and the output current = L3-02, the drive will start deceleration as
specified by the value set in L3-22 [PM Stall Prevention Decel Time]. The drive starts acceleration again when
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