L3: Stall Prevention - YASKAWA GA700 Technical Manual

Set L2-06 to the time necessary to decelerate from the frequency reference to 0 Hz when a momentary power loss
is detected. Deceleration can be performed while maintaining constant deceleration rates for multiple drives.
Note:
Doing so may cause ov faults to occur. Use the dynamic braking option with System KEB Ride-Thru 1.
3 : System KEB Ride-Thru 2
The drive performs deceleration over the deceleration time set in L2-06 while monitoring the DC bus voltage.
If the DC bus voltage rises, the frequency is momentarily held steady to prevent an ov issue while deceleration
continues.
Note:
Use System KEB Ride-Thru 2 when the dynamic braking option cannot be used.
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L2-30: KEB Zero Speed Operation
No.
Name
(Hex.)
L2-30 KEB Zero Speed
Operation
(045E)
0 : Baseblock
1 : DC/SC Braking
Performs DC injection braking and short circuit braking in accordance with b2-04 [DC Inject Braking Time at
Stop] and b2-13 [Short Circuit Brake Time @ Start].
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L2-31: KEB Start Voltage Offset Level
No.
Name
(Hex.)
L2-31 KEB Start Voltage
Offset Level
(045D)
The KEB start voltage is calculated with the following expression.
KEB start voltage = L2-05 [Undervoltage Detect Level (Uv1)] + L2-31
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L3: Stall Prevention

L3 parameters set the Stall Prevention function and overvoltage suppression function.
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Stall Prevention
The motor may experience excessive slip because it cannot keep up with the frequency reference when the load is
too high or acceleration and deceleration times are too short. If the motor stalls during acceleration, current
increases in accordance with the increase in slip, which causes an oC [Overcurrent], oL2 [Drive Overloaded], or
oL1 [Motor Overload] and the drive to stop. If the motor stalls during deceleration, it can cause excessive
regenerative power to flow back into the DC bus capacitors, and eventually cause the drive to fault out from ov
[DC Bus Overvoltage] to be detected and the drive to stop.
The stall prevention function prevents the motor from stalling and while allowing the motor to reach the desired
speed without requiring the user to change the acceleration or deceleration time settings. The stall prevention
function can be set separately for acceleration, operating at constant speeds, and deceleration.
■
Overvoltage Suppression Function
Suppresses ov by decreasing the regenerative torque limit and slightly increasing the output frequency when the
DC bus voltage rises. This function can drive loads with cyclic regenerative operation, such as a punch press or
other applications that involve repetitive crank movements. Set L3-11 = 1 [OV Suppression Function Select =
Enabled] when using this function.
The regenerative torque limit and the output frequency are adjusted during overvoltage suppression so that the DC
bus voltage does not exceed the level set to L3-17 [ DC Bus Reg Level].
YASKAWA ELECTRIC SIEP C710617 01B YASKAWA AC Drive GA700 Technical Manual
V/f CL-V/f OLV CLV AOLV
Selects the operation when the output frequency drops below the zero level
(DC braking injection starting frequency) during KEB deceleration when
L2-01 = 3 to 5 [Momentary Power Loss Ope Select = KEB Mode, KEB Stop
Mode, or KEB Decel to Stp].
V/f CL-V/f OLV CLV AOLV
Configures the KEB start voltage offset.
Description
OLV/PM AOLV/PM CLV/PM EZOLV OLV/PM
Description
OLV/PM AOLV/PM CLV/PM EZOLV OLV/PM
11.9 L: Protection Function
Default Setting
(Range)
0
(0, 1)
Default Setting
(Range)
Determined by A1-02
(200 V Class: 0 - 100
V, 400 V Class: 0 -
200 V)
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