YASKAWA A1000 Technical Manual page 275

Setting 4: KEB Ride-Thru as long as CPU has power
The drive decelerates using regenerative energy from the motor until the power returns and then restarts. If the motor has
come to a stop before, the power returns. If the drive control power gets lost, the drive output will shut off. A Uv1 fault is
not triggered. The type of KEB operation is determined by the setting of L2-29.
Setting 5: Ramp to stop with KEB deceleration
The drive ramps to stop using the regenerative energy from the motor. Even if the power is restored, the drive will
continue decelerating until it brings the motor to a complete stop. The type of KEB operation is determined by the setting
of parameter L2-29.
Notes on Settings 1 through 5
• "Uv" will flash on the operator while the drive is attempting to recover from a momentary power loss. A fault signal is
not output at this time.
• A Momentary Power Loss Unit is available to allow for a longer momentary power loss ride through time in the drive
model CIMR-A2A0004 through 2A0056 and CIMR-A4A0002 through 4A0031. This option makes it possible to
continue running after up to two seconds of power loss.
• When a magnetic contactor between motor and drive is used, be sure that the magnetic contactor remains closed as
long as the drive performs KEB operation or attempts to restart with Speed Search.
• Make sure the Run command is kept active during KEB operation. Otherwise the drive cannot accelerate back to the
frequency reference when the power returns.
• When L2-01 is set to 3, 4, or 5, KEB Ride-Thru will be executed as specified in L2-29.

KEB Ride-Thru Function
When power loss is detected, the Kinetic Energy Backup Ride-Thru function (KEB Ride-Thru) decelerates the motor and
uses regenerative energy to keep the main circuit operating. Despite power loss, the drive output is not interrupted.
For applications driven by a single drive, choose between Single Drive KEB Ride-Thru 1 and 2 (L2-29 = 0 or 1).
For applications where multiple drives have to perform KEB operation while keeping a certain speed ratio (such as
textile machinery), select between System KEB Ride-Thru 1 and 2, (L2-29 = 2 or 3).
Single Drive KEB Ride-Thru 1 (L2-29 = 0)
Once KEB Ride-Thru begins, the drive uses regenerative energy from the motor to keep the DC bus voltage at the level
set to L2-11 while adjusting the rate of deceleration based on the time set to C1-09.
Note: If undervoltage occurs in the DC bus (Uv1), shorten the Fast Stop Time (C1-09). If overvoltage occurs (oV), increase the KEB
deceleration time.
Single Drive KEB Ride-Thru 2 (L2-29 = 1)
The drive uses information about the inertia of the connected machinery to determine the deceleration rate necessary to
keep the DC bus voltage at the level set in parameter L2-11. The resulting deceleration time is calculated based on the
system inertia and cannot be adjusted.
System KEB Ride-Thru 1 (L2-29 = 2)
Drive decelerates at the KEB deceleration time set to L2-06. L2-06 is the time required decelerate from the current
frequency reference to 0. Using this setting, multiple drives can decelerate while still keeping the speed ratio between
those drives constant. The voltage level in the DC bus is disregarded when using this function. Braking resistor option
required.
System KEB Ride-Thru 2 (L2-29 = 3)
Drive decelerates based on the KEB deceleration time set to L2-06 while monitoring the DC bus voltage. If the voltage
level rises, the drive briefly holds the frequency before continuing to decelerate again.
YASKAWA ELECTRIC SIEP C710616 27G YASKAWA AC Drive A1000 Technical Manual
5.8 L: Protection Functions
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