YASKAWA A1000 Technical Manual page 285

Setting 1: Decelerate using C1-02
If the current exceeds the Stall Prevention level set in parameter L3-06, then the drive will decelerate at decel time
(C1-02, C1-04, C1-06, C1-08). Once the current level drops below the value of L3-06 minus 2% for 100 ms, the drive
accelerates back to the frequency reference at the active acceleration time.
Setting 2: Decelerate using C1-04
Same as setting 1 except the drive decelerates at decel time 2 (C1-04).

L3-06: Stall Prevention Level during Run
Sets the current level to trigger Stall Prevention during run. Depending on the setting of parameter L3-23, the level is
automatically reduced in the constant power range (speed beyond base speed). A setting of 100% is equal to the drive
rated current.
The Stall Prevention level can be adjusted using an analog input. Refer to
Settings on page 260 for details.
No.
L3-06
<1> The upper limit and default for this setting is determined by C6-01 and L8-38.

Overvoltage Suppression Function
This function suppresses overvoltage faults by decreasing the regenerative torque limit and slightly increasing the output
frequency when the DC bus voltage rises. It can be used to drive loads with cyclic regenerative operation, such as a
punch press or other applications that involve repetitive crank movements.
The regenerative torque limit and the output frequency are adjusted during ov suppression so that the DC bus voltage
does not exceed the level set in parameter L3-17. In addition to the parameters explained below, ov suppression also uses
these settings for frequency adjustment:
• 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: 1. The motor speed will exceed the frequency reference when overvoltage suppression is triggered. Consequently, overvoltage
suppression is not appropriate in applications that require a perfect match between the frequency reference and the motor speed.
2. Disable overvoltage suppression when using a braking resistor.
3. Overvoltage may still occur if there is a sudden increase to a regenerative load.
4. This function is enabled only when operating just below the maximum frequency. Overvoltage suppression does not increase the
output frequency beyond the maximum frequency. If this is required by the application, increase the maximum frequency and change
the base frequency setting.

L3-11: Overvoltage Suppression Function Selection
Enables or disables the overvoltage suppression function.
No.
L3-11
Setting 0: Disabled
The regenerative torque limit and the output frequency are not adjusted. A regenerative load may trip the drive with an
overvoltage fault. Use this setting if dynamic braking options are installed.
Setting 1: Enabled
When the DC bus voltage rises due to regenerative load, an overvoltage fault is prevented by decreasing the regenerative
torque limit and increasing the output frequency.
YASKAWA ELECTRIC SIEP C710616 27G YASKAWA AC Drive A1000 Technical Manual
Name
Stall Prevention Level During Run
Name
Overvoltage Suppression Function Selection
5.8 L: Protection Functions
Multi-Function Analog Input Terminal
Setting Range
30 to 150%
<1>
Setting Range
0 or 1
Default
<1>
5
Default
0
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