L3: Stall Prevention - YASKAWA GA700 Series Technical Manual

12.9 L: Protection Functions
Note:
• If the drive detects Uv1 [DC Bus Undervoltage] during KEB operation, decrease the value of C1-09.
• If the drive detects ov [Overvoltage] during KEB operation, increase the value of C1-09.
1 : Single Drive KEB Ride-Thru 2
The drive does KEB operation and automatically calculates the deceleration rate to make sure that the main circuit
electrical energy and main current voltage from motor regenerative energy is equal to L2-11.
2 : System KEB Ride-Thru 1
The drive does not monitor the DC bus voltage and decelerates as specified by the KEB deceleration time set in
L2-06.
Use L2-06 to set the time necessary to decelerate from the current frequency reference to 0 Hz. More than one
drive can decelerate and keep a constant speed ratio between drives.
Note:
If you keep constant deceleration rates for more than one drive, it can trigger ov faults. Use the dynamic braking option with System
KEB Ride-Thru 1.
3 : System KEB Ride-Thru 2
The drive uses the KEB deceleration time set in L2-06 to decelerate and it also monitors the DC bus voltage.
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.
Name
(Hex.)
L2-30 KEB Zero Speed Operation
(045E)
Expert
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.
Name
(Hex.)
L2-31 KEB Start Voltage Offset
Level
(045D)
Expert
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.
886
V/f CL-V/f OLV CLV AOLV
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].
V/f CL-V/f OLV CLV AOLV
Sets 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
YASKAWA SIEPC71061705H GA700 Series Technical Manual
Default
(Range)
0
(0, 1)
Default
(Range)
Determined by A1-02
(200 V Class: 0 - 100 V,400
V Class: 0 - 200 V)