YASKAWA GA800 Technical Reference page 971

If the drive detects momentary power loss, the drive will use regenerative energy from the motor and ramp to stop.
When you return power in the time set in L2-02, the drive will accelerate to the frequency reference value that the
drive used before the power loss. If you do not return power in the time set to L2-02, the drive will detect Uv1 and the
drive output will turn OFF. L2-29 [Kinetic Energy Backup Method] sets the type of KEB operation.
4 : Kinetic Energy Backup: CPU Power
When power returns and the drive control circuit has power, the drive will restart.
The drive decelerates using regenerative energy from the motor until the power returns and then restarts when a
momentary power loss is detected. When power is restored during deceleration, the drive accelerates the motor again
to the frequency reference value used before the power loss. If the motor comes to a stop before the power returns, the
drive loses control power and the drive output shuts off. A Uv1 is not triggered when power is restored while power to
the CPU in the drive is maintained. L2-29 sets the type of KEB operation.
5 : Kinetic Energy Backup: DecelStop
When power returns, the drive will continue to decelerate until the motor fully stops.
If the drive detects momentary power loss, the drive will use regenerative energy from the motor and ramp to stop.
When you return power to the drive, the drive will continue to decelerate until the motor comes to a full stop. After
you return power, the drive will ramp to stop in the set deceleration time. L2-29 sets the type of KEB operation.
Note:
When you set L2-01, make sure that you know these items:
• You can use a Momentary Power Loss Unit on models 2004 to 2056 and 4002 to 4031 for a longer momentary power loss ride through
time. A Momentary Power Loss Unit makes it possible to continue operation of the drive after a maximum of 2 seconds of power loss.
• When you set L2-01 = 1 to 4, keep the magnetic contactor on the drive input side ON and keep the control signal while the drive does KEB
operation.
• When L2-01 = 1 to 5, Uv [DC Bus Undervoltage] will flash on the keypad while the drive is attempting to recover from a momentary
power loss. The drive will not output a fault signal at this time.
• When you use a magnetic contactor between the motor and the drive, keep the magnetic contactor closed while the drive does KEB
operation or tries to restart with Speed Search.
• Keep the Run command active during KEB operation. The drive cannot accelerate back to the frequency reference when the power returns.
• When L2-01 = 3 to 5, if the control power supply voltage is less than the CPU operation level during KEB Ride-Thru, it will trigger Uv1.
• When the CPU is inactive, b1-17 [Run Command at Power Up] sets operation at power up.
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L2-02: Power Loss Ride Through Time
No.
Name
(Hex.)
L2-02 Power Loss Ride Through
Time
(0486)
This function is applicable when L2-01 = 1, 3 [Power Loss Ride Through Select = Enabled for L2-02 Time, Kinetic
Energy Backup: L2-02]. If power loss operation is longer than the time set in this parameter, the drive will detect Uv1
[DC Bus Undervoltage], turn OFF output, and the motor will coast to stop.
Note:
• The length of time that the drive can recover after a power loss changes when drive capacity changes.
• The upper limit of the possible momentary power loss Ride-Thru time changes when drive capacity changes.
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L2-03: Minimum Baseblock Time
No.
Name
(Hex.)
L2-03 Minimum Baseblock Time
(0487)
Sets the length of time that the drive will wait for the residual voltage in the motor to dissipate in estimation to the
secondary circuit time constant of the motor. If oC [Overcurrent] or ov [DC Bus Overvoltage] occur at the start of
Speed Search, after power returns, or during DC Injection Braking, increase this setting.
YASKAWA SIEPC71061737D GA800 Drive Technical Reference
V/f CL-V/f OLV CLV AOLV
Sets the maximum time that the drive will wait until trying to restart after power loss.
V/f CL-V/f OLV CLV AOLV
Sets the minimum time to continue the drive output block (baseblock) after a baseblock.
12.9 L: Protection Functions
Description
OLV/PM AOLV/PM CLV/PM EZOLV OLV/PM
Description
OLV/PM AOLV/PM CLV/PM EZOLV OLV/PM
Default
(Range)
Determined by o2-04, C6-01
(0.0 - 25.5 s)
Default
(Range)
Determined by o2-04, C6-01
(0.1 - 5.0 s)
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