12.9 L: Protection Functions
706 YASKAWA SIEPC71061753C GA500 Technical Manual
When you return power while KEB is operating, the drive continues KEB operation until the time set in L2-10 is
expired. When the DC bus voltage is less than the level of L2-05 [Undervoltage Detection Lvl (Uv1)] in one of
these conditions, KEB operation continues until the time set in L2-10 is expired:
• L2-01 = 3 [Power Loss Ride Through Select = Kinetic Energy Backup: L2-02]
• L2-01 = 4 [Kinetic Energy Backup: CPU Power]
• L2-01 = 5 [Kinetic Energy Backup: DecelStop]
• KEB Ride-Thru 1/2 [H1-xx = 65, 66, 7A, or 7B] is input into the drive.
When you input KEB Ride-Thru, KEB operation continues after the time set in L2-10 is expired. When you
cancel KEB Ride-Thru, the motor accelerates again. When you do not input KEB Ride-Thru during the time set in
L2-10, the drive accelerates to the frequency reference that the drive had before power loss in the applicable
acceleration time.
When L2-01 = 3, 4, or 5, and the DC bus voltage is a minimum of the value of L2-11 [KEB DC Bus Voltage
Setpoint], the drive accelerates again after the time set in L2-10 is expired. When the DC bus voltage is less than
the L2-11 value, KEB operation continues after the time set in L2-10 is expired.
Note:
• When L2-01 = 0, 1, or 2 [Disabled, Enabled for L2-02 Time, or Enabled while CPU Power Active], increase the value of L2-10. Set
L2-10 to cancel KEB operation if the KEB Ride-Thru is not input.
• Setting L2-10 to 0 ms disables the function of L2-10.
■ L2-11: KEB DC Bus Voltage Setpoint
No.
(Hex.)
Name Description
Default
(Range)
L2-11
(0461)
Expert
KEB DC Bus Voltage
Setpoint
Sets the target value that controls the DC bus voltage to a constant level in Single Drive KEB
Ride-Thru 2. Sets the DC bus voltage level that completes the KEB operation for all other KEB
methods.
Determined by E1-01
(Determined by E1-01)
■ L2-29: Kinetic Energy Backup Method
No.
(Hex.)
Name Description
Default
(Range)
L2-29
(0475)
Expert
Kinetic Energy Backup
Method
Sets the KEB function operation mode.
0
(0 - 3)
Set L2-01 = 3, 4, or 5 [Power Loss Ride Through Select = Kinetic Energy Backup: L2-02, Kinetic Energy
Backup: CPU Power, or Kinetic Energy Backup: DecelStop] or KEB Ride-Thru 1/2 [H1-xx = 65, 66, 7A, or 7B],
to enable the KEB function.
0 : Single Drive KEB Ride-Thru 1
The drive monitors the DC bus voltage and uses regenerative energy from the motor to hold the DC bus voltage at
the level set in L2-11 [KEB DC Bus Voltage Setpoint].
The KEB operation continues and the deceleration rate changes as specified by C1-09 [Fast Stop Time].
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.
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