Parameter Details
12
12.9 L: Protection Functions
YASKAWA SIEPC71061753C GA500 Technical Manual 707
If the voltage level increases, the drive momentarily holds the frequency to prevent an ov before it continues to
decelerate.
Note:
When you cannot use a dynamic braking option, use System KEB Ride-Thru.
■ L2-30: KEB Zero Speed Operation
No.
(Hex.)
Name Description
Default
(Range)
L2-30
(045E)
Expert
KEB Zero Speed Operation
Sets the operation when the output frequency decreases below the zero level (DC braking
injection starting frequency) during KEB deceleration when L2-01 = 3 to 5 [Power Loss Ride
Through Select = Kinetic Energy Backup: L2-02, Kinetic Energy Backup: CPU Power, or Kinetic
Energy Backup: DecelStop].
0
(0, 1)
0 : Baseblock
1 : DC/SC Braking
Does DC injection braking and short circuit braking as specified by b2-04 [DC Inject Braking Time at Stop] and
b2-13 [Short Circuit Brake Time @ Stop].
■ L2-31: KEB Start Voltage Offset Level
No.
(Hex.)
Name Description
Default
(Range)
L2-31
(045D)
Expert
KEB Start Voltage Offset
Level
Sets the KEB start voltage offset.
Determined by A1-02
(200 V Class: 0 - 100 V,400
V Class: 0 - 200 V)
The drive uses this formula to calculate the KEB start voltage:
KEB start voltage = L2-05 [Undervoltage Detect Level (Uv1)] + L2-31
◆ L3: Stall Prevention
L3 parameters set the Stall Prevention function and overvoltage suppression function.
■ Stall Prevention
If the load is too heavy or the acceleration and deceleration times are too short, the motor can slip too much
because it cannot work at the same rate as the frequency reference. If the motor stalls during acceleration, current
increases as the slip increases to cause an oC [Overcurrent], oL2 [Drive Overload], or oL1 [Motor Overload] and
the drive will stop. If the motor stalls during deceleration, too much regenerative power will flow back into the
DC bus capacitors, and cause the drive to detect an ov [Overvoltage] fault and stop.
The stall prevention function will let the motor get to the set speed without stalling and it is not necessary for you
to change the acceleration or deceleration time settings. You can set a separate stall prevention functions for
acceleration, operating at constant speeds, and deceleration.
■ Overvoltage Suppression Function
Decreases the regenerative torque limit and increases the output frequency when the DC bus voltage increases to
prevent ov. This function can drive loads with cyclic regenerative operation, for example punch presses or other
applications with repeated crank movements. When you use this function, set L3-11 = 1 [Overvoltage Suppression
Select = Enabled].
The drive adjusts the regenerative torque limit and the output frequency during overvoltage suppression to make
sure that the DC bus voltage is not more than the level set in L3-17 [DC Bus Regulation Level].
Set these parameters as necessary when you use the overvoltage suppression function:
• L3-20 [DC Bus Voltage Adjustment Gain]
• L3-21 [OVSuppression Accel/Decel P Gain]
• L3-24 [Motor Accel Time @ Rated Torque]
• L3-25 [Load Inertia Ratio]
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