5.8 L: Protection FunctionsYASKAWA ELECTRIC SIEP C710616 27G YASKAWA AC Drive A1000 Technical Manual 275Parameter Details5Setting 4: KEB Ride-Thru as long as CPU has powerThe drive decelerates using regenerative energy from the motor until the power returns and then restarts. If the motor hascome to a stop before, the power returns. If the drive control power gets lost, the drive output will shut off. A Uv1 fault isnot triggered. The type of KEB operation is determined by the setting of L2-29.Setting 5: Ramp to stop with KEB decelerationThe drive ramps to stop using the regenerative energy from the motor. Even if the power is restored, the drive willcontinue decelerating until it brings the motor to a complete stop. The type of KEB operation is determined by the settingof 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 isnot output at this time.• A Momentary Power Loss Unit is available to allow for a longer momentary power loss ride through time in the drivemodel CIMR-A2A0004 through 2A0056 and CIMR-A4A0002 through 4A0031. This option makes it possible tocontinue 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 aslong 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 thefrequency 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 FunctionWhen power loss is detected, the Kinetic Energy Backup Ride-Thru function (KEB Ride-Thru) decelerates the motor anduses 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 astextile 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 levelset 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 KEBdeceleration 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 tokeep the DC bus voltage at the level set in parameter L2-11. The resulting deceleration time is calculated based on thesystem 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 currentfrequency reference to 0. Using this setting, multiple drives can decelerate while still keeping the speed ratio betweenthose drives constant. The voltage level in the DC bus is disregarded when using this function. Braking resistor optionrequired.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 voltagelevel rises, the drive briefly holds the frequency before continuing to decelerate again.
