5.8 L: Protection Functions
220 YASKAWA ELECTRIC SIEP C710616 30B YASKAWA AC Drive T1000A Technical Manual
n L3-04: Stall Prevention Selection during Deceleration
Stall Prevention during deceleration can control the deceleration based on the DC bus voltage and prevent an overvoltage
fault caused by high inertia or rapid deceleration.
Setting 0: Disabled
When this setting is used, the drive decelerates according to the set deceleration time. With high inertia loads or rapid
deceleration, an overvoltage (ov) fault may occur. In this case use braking options or switch to another L3-04 selection.
Setting 1: General-purpose Stall Prevention
With this setting the drive tries to decelerate within the set deceleration time. When the DC bus voltage exceeds the Stall
Prevention level, the drive pauses deceleration. Deceleration continues as soon as the DC bus voltage drops below that
level. Stall Prevention may be triggered repeatedly to avoid an overvoltage fault. The DC bus voltage level for Stall
Prevention depends on the input voltage setting E1-01.
Note: 1. This setting should not be used in combination with a Dynamic Braking Resistor or other braking options. If Stall Prevention during
deceleration is enabled, it will be triggered before the braking resistor option can operate.
2. This method may lengthen the total deceleration time compared to the set value. If this is not appropriate for the application consider
using a braking option.
Figure 5.84 illustrates the function of Stall Prevention during deceleration.
Figure 5.84
Figure 5.84 Stall Prevention During Deceleration
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. This way the shortest possible deceleration time is achieved while the motor is protected from stalling. The
deceleration time that has been selected is disregarded, but the achievable deceleration time cannot be smaller than 1/10
of the set deceleration time.
This function uses the following parameters to calculate the deceleration rate:
• DC Bus Adjustment Gain (S6-04)
• Accel/Decel Calculation Gain (S6-05)
• Motor Acceleration Time (S6-02)
• Load Inertia Ratio (S6-03)
• Additional DC Bus Capacitors (L3-26)
• DC Bus Capacity (S6-01)
For descriptions regarding the S6 parameters refer to section S6: Power KEB Function on page 260.
Note: As the deceleration time is not constant, Intelligent Stall Prevention should not be used in applications where stopping accuracy
is a concern. Use braking options instead.
No.
<1> Settings 3 through 5 are not available in OLV/PM. Settings 2 through 5 are not available in AOLV/PM and CLV/PM.
Name Setting Range Default
L3-04 Stall Prevention Selection During Deceleration 0 to 5 <1> 1
Drive Input Voltage Stall Prevention Level during Deceleration
200 V Class 377 Vdc
400 V Class 754 Vdc
Output Frequency
Deceleration characteristics
when Stall Prevention was
triggered during deceleration
Time
specified deceleration time
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