YASKAWA A1000 Technical Manual page 284

5.8 L: Protection Functions
Figure 5.104 illustrates the function of Stall Prevention during deceleration.
Figure 5.104
Setting 2: Intelligent Stall Prevention
With this setting, the drive adjusts the deceleration rate so that the DC bus voltage is kept at the level set in parameter
L3-17. As the result, the drive ignores the selected deceleration time and uses the shortest possible deceleration time that
will not cause the motor to stall.
This function uses the following parameters for adjusting the deceleration rate:
• DC bus voltage gain (L3-20)
• Deceleration rate calculations gain (L3-21)
• Inertia calculations for motor acceleration time (L3-24)
• Load inertia ratio (L3-25)
Note: As the deceleration time is not constant, Intelligent Stall Prevention should not be used in applications where stopping accuracy
is a concern. Use dynamic braking options instead.
Setting 3: Stall Prevention with dynamic braking option
Note: The setting of 3 is not available with models CIMR-A4A0930 and 4A1200.
Enables the Stall Prevention function while using a dynamic braking resistor. Overvoltage problems in the DC bus can
occur if Stall Prevention during deceleration is disabled (L3-04) in OLV and a dynamic braking option is installed. Set
L3-04 to 3 to remedy this situation.
Setting 4: Overexcitation Deceleration 1
Decelerates with the set deceleration rate in an overexcitation state (increasing the motor flux). The motor will decelerate
when Stall Prevention is disabled (L3-04). Setting 4 changes the selected decel time and functions to provide protection
from an overvoltage trip. Refer to
Setting 5: Overexcitation Deceleration 2
Overexcitation Deceleration 2 slows down the motor while trying to maintain the DC bus voltage at the level set to
parameter L3-17. This function shortens the achievable deceleration time more than by using Overexcitation
Deceleration 1. Setting 5 will shorten/lengthen the decel time to maintain the L3-17 bus level. Refer to
Deceleration (Induction Motors) on page 304

L3-05: Stall Prevention Selection during Run
Stall Prevention during run can prevent a motor from stalling by automatically reducing the speed when a transient
overload occurs while the motor is running at constant speed.
This parameter determines how Stall Prevention works during run.
No.
L3-05
Note: 1. This parameter is available in V/f, V/f w/PG, and OLV/PM.
2. When output frequency is 6 Hz or less, Stall Prevention during run is disabled regardless of the setting in L3-05 and L3-06.
Setting 0: Disabled
Drive runs at the set frequency reference. A heavy load may cause the motor to stall and trip the drive with an oC or oL
fault.
284
Output Frequency
specified deceleration time
Figure 5.104 Stall Prevention During Deceleration
Overexcitation Deceleration (Induction Motors) on page 304
for details.
Name
Stall Prevention Selection During Run
YASKAWA ELECTRIC SIEP C710616 27G YASKAWA AC Drive A1000 Technical Manual
Deceleration characteristics
when Stall Prevention was
triggered during deceleration
Time
Setting Range
0 to 2
for details.
Overexcitation
Default
1