L3: Stall Prevention - YASKAWA U1000 Series Technical Manual

5.8 L: Protection Functions
 L3: Stall Prevention
When the load is too high or acceleration and deceleration times are too short, the motor may be unable to keep up with
the frequency reference, resulting in excessive slip. During acceleration, this usually causes an overcurrent fault (oC),
overload (oL2), or motor overload (oL1). During deceleration, it can cause the drive to fault out from overvoltage (oV).
The drive can prevent the motor from stalling and still reach the desired speed without the user needing to change the
acceleration or deceleration time 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 overload
(oL2) faults common when accelerating with heavy loads.
L3-01 determines the type of Stall Prevention the drive should used during acceleration.
No.
L3-01
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, thus tripping an overload fault.
Setting 1: Enabled
Enables Stall Prevention during acceleration. Operation varies, depending on the control mode.
• V/f Control, V/f Control with PG, and Open Loop Vector Control:
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.
Limit during Acceleration/Deceleration on page
Figure 5.91
264
Name
Stall Prevention Selection during Acceleration
Output current
Stall Prevention Level
During Acceleration
L3-02
L3-02
-15%
Output frequency
Controls the output frequency
to prevent the motor from stalling
Figure 5.91 Stall Prevention During Acceleration for Induction Motors
265.
common_TMonly
YASKAWA ELECTRIC SIEP C710636 03A YASKAWA U1000 Technical Manual
Setting Range
0, 1, 3
Refer to L3-03: Stall Prevention
Time
Time
Default
1