5.8 L: Protection Functions
♦ L3: Stall Prevention
When the load is too heavy or acceleration ramps are too short, the motor may be unable to keep up with the speed
reference, resulting in excessive slip. During acceleration, this usually causes an overcurrent fault (oC), drive overload
(oL2), or motor overload (oL1). The drive can prevent the motor from stalling and still reach the desired speed without
the user needing to change the acceleration or deceleration ramp settings. The Stall Prevention function can be set
separately for acceleration, operating at constant speeds, and deceleration.
■ L3-01: Stall Prevention Selection during Acceleration
Stall Prevention during acceleration (L3-01) prevents tripping with overcurrent (oC), motor overload (oL1), or drive
overload (oL2) faults common when accelerating with heavy loads.
L3-01 determines the type of Stall Prevention the drive uses during acceleration.
No.
Name
Setting Range
Default
L3-01
Stall Prevention Selection during Acceleration
0 to 2
1
Setting 0: Disabled
No Stall Prevention is provided. If the acceleration time is too short, the drive may not be able to get the motor up to
speed fast enough, causing an overload fault.
Setting 1: Enabled
Enables Stall Prevention during acceleration.
If the output current rises above the Stall Prevention level set in L3-02, then the drive stops accelerating. Acceleration
will not resume until the output current falls 15% below the setting in L3-02.
The Stall Prevention level is automatically reduced in the constant power range.
Output current
Setting 2: Intelligent Stall Prevention
The drive disregards the selected acceleration time and attempts to accelerate in the minimum time. The acceleration rate
is adjusted so the current does not exceed the value set to parameter L3-02.
■ L3-02: Stall Prevention Level during Acceleration
Sets the output current level at which the Stall Prevention during acceleration is activated.
No.
Name
Setting Range
Default
L3-02
Stall Prevention L evel during Acceleration
0 to 150% <1>
<1>
<1> The upper limit and default value are determined by the carrier frequency reduction (L8-38).
• Lower L3-02 if stalling occurs when using a motor that is relatively small compared to the drive.
• Also set parameter L3-03 when operating the motor in the constant power range.
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YASKAWA ELECTRIC SIEP C710616 33D YASKAWA AC Drive L1000A Technical Manual