12.8 L: PROTECTION
762 SIEPYEUOQ2A01A AC Drive Q2A Technical Manual
Figure 12.132 Stall Prevention Operation during Deceleration
1 : Automatic Decel Reduction
The drive adjusts the deceleration rate to keep the DC bus voltage at the L3-17 [DCBus Regul.Level] level. This
makes the shortest possible deceleration time and will not let the motor stall. The drive ignores the selected
deceleration time and the possible deceleration time cannot be less than 1/10 of the set deceleration time.
This function uses these parameters to adjust the deceleration rate:
• L3-20 [DCBus VoltAdj Gain]
• L3-21 [OVSup Acc/Dec Gain]
• L3-24 [Acc@Rated Torque]
• L3-25 [Load Inertia Ratio]
Note:
The deceleration time is not constant. For applications where the precision of the stop position is very important, use a dynamic braking
option and set L3-04 = 0. If an ov occurs, set L3-04 = 3.
2 : Gen Purpose w/ DB Resistor
A braking resistor is necessary for this setting. The braking resistor and the drive work together for the Stall
Prevention during deceleration function.
3 : HiFlux Overexcitation
Enables Overexcitation/High Flux and enables a shorter deceleration time than when L3-04 = 0.
Note:
• If the overexcitation time is long and you decelerate frequently, the drive can detect oL1 [Motor Overload] faults. If the drive detects
oL1, decrease the deceleration time or install a braking resistor to the drive.
• The deceleration time during Overexcitation Deceleration changes when the motor characteristics and machine inertia change. Adjust
the n3-13 [OverExcBr Gain] and n3-23 [OverExcBr Operation] levels. Refer to “n3: HIGHSLIP/OVEREXCITATION BRAKE” for
more information.
4 : HiFlux2 Overexcitation
Enables Overexcitation/High Flux 2. This function decreases the possible deceleration time more than
Overexcitation/High Flux.
The drive decreases motor speed and tries to keep the DC bus voltage at the L3-17 level.
If the drive detects oL1, decrease the values set in n3-13 and n3-21. If the drive detects ov, increase the values set
in C1-02, C1-04, C1-06, and C1-08 [Decel Time 4].
Note:
• During Overexcitation/High Flux 2, the drive disables Hunting Prevention in V/f Control and also disables Speed Control that uses
torque limit in OLV Control.
• Refer to “n3: HIGHSLIP/OVEREXCITATION BRAKE” for more information.
■ L3-51 StallP@RUNDecTime
No.
(Hex.)
Name Description
Default
(Range)
L3-51
(0459)
StallP@RUNDecTime
Sets the function to enable and disable Stall Prevention During Run.
0
(Determined by A1-02)
0 : Dec Time 1 (C1-02)
1 : Dec Time 2 (C1-04)
◆ L4: SPEED DETECTION
L4 parameters set the output of signals to the MFDO terminals, for example frequency agree and speed detection.
The drive detects motor speed in CLV or CLV/PM control methods.
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