12.8 L: PROTECTION
752 SIEPYEUOQ2A01A AC Drive Q2A Technical Manual
■ L2-30 KEB ZeroSpeed Operation
No.
(Hex.)
Name Description
Default
(Range)
L2-30
(045E)
Expert
KEB ZeroSpeed Operation
Sets the operation when the output frequency decreases below the zero level (DC braking
injection starting frequency) during KEB deceleration when L2-01 = 1 [RideThru@PwrLoss =
Enabled and L2-50 = 2 to 4 [RidThruMode@PwrLoss= KEB Mode, KEB Stop Mode, or KEB
Decel to Stop].
1
(1, 2)
1 : Baseblock
2 : DC/SC Braking
Does DC injection braking and short circuit braking as specified by b2-04 [DCInj Time@Stop] and b2-13 [SCB
Time@Stop].
■ L2-31 KEB StartV Offset Level
No.
(Hex.)
Name Description
Default
(Range)
L2-31
(045D)
Expert
KEB StartV Offset Level
Sets the KEB start voltage offset.
Determined by A1-02
(400 V Class: 0 - 200 V)
The drive uses this formula to calculate the KEB start voltage:
KEB start voltage = L2-31 + L2-05 [UV Detection Lvl (Uv1)]
■ L2-50 RidThruMode@PwrLoss
No.
(Hex.)
Name Description
Default
(Range)
L2-50
(###)
Expert ##??##
RidThruMode@PwrLoss
Sets the drive operation after a momentary power loss..
0
(0 - 4)
0 : Timer Controlled
When power returns in the time set in L2-02 [RideThrough Time@Power Loss], the drive will restart. If power
does not return in the time set in L2-02, the drive will detect Uv1.
The drive momentarily turns OFF its output after a power loss. If the power returns in the time set to L2-02, the
drive will do Speed Search and try to continue operation.
If the DC bus voltage is less than or equal to the Uv1 detection level for the time set in L2-02, the drive will detect
Uv1 and output a fault signal.
Note:
• The necessary time for the drive to restart after power returns is different for different drive capacities.
• The upper limit of the possible momentary power loss Ride-Thru time is different for different drive models.
1 : While CPU Active
When power returns and the drive control circuit has power, the drive will restart. This will not trigger Uv1.
When there is a momentary power loss, the drive output will turn OFF. If the power returns and the drive control
circuit has power, the drive will do Speed Search and try to continue operation. This will not trigger Uv1. This
function lets the power loss be longer than when L2-01 = 1.
2 : KEB Mode
If power does not return in the time set in L2-02, the drive will detect Uv1.
When the drive detects momentary power loss, the drive will use regenerative energy from the motor through
KEB operation to decelerate. When you return power in the time set in L2-02, the drive will accelerate to the
frequency reference value that was 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.
3 : KEB Stop Mode
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
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