5.8 L: Protection FunctionsYASKAWA ELECTRIC SIEP C710616 27C YASKAWA AC Drive A1000 Technical Manual 249Parameter Details5◆ L2: Momentary Power Loss Ride-Thru■ L2-01: Momentary Power Loss Operation SelectionWhen a momentary power loss occurs (DC bus voltage falls below the level set in L2-05), the drive can be set toautomatically return to the operation it was performing when the power went out based on certain conditions.Setting 0: Disabled (default)If power is not restored within 15 ms, a Uv1 fault will result and the drive will stop the motor. The motor coasts to stop.Setting 1: Recover within L2-02When a momentary power loss occurs, the drive output will be shut off. Should the power return within the time set toparameter L2-02, the drive will perform Speed Search and attempt to resume operation. If power is not restored withinthis time (i.e., DC bus voltage level remains below Uv1 detection level L2-05), then a Uv1 fault is triggered.Setting 2: Recover as long as CPU has powerWhen a momentary power loss occurs, the drive output will be shut off. Should the power return as long as the drivecontrol circuit has power, the drive will attempt to perform Speed Search and resume the operation. A Uv1 fault is nottriggered.Setting 3: KEB Ride-Thru operation within L2-02The drive decelerates using regenerative energy from the motor until the time set in L2-02 has expired. It then tries toaccelerate back to the frequency reference. If the power does not returned within the time set in L2-02, an Uv1 fault istriggered and the drive output shuts off. The type of KEB operation is determined by the setting of L2-29.Setting 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. Note that if an input terminal set for KEB 1 (H1- = 65, 66) is triggered while the drive isdecelerating, then it will accelerate back up to speed when the input is released.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).No. Name Setting Range DefaultL2-01 Momentary Power Loss Operation Selection 0 to 5 0
