11.10 n: Special Adjustment878 YASKAWA ELECTRIC SIEP C710617 01B YASKAWA AC Drive GA700 Technical Manual– Continuous regenerative loads– Reacceleration is required during deceleration• Motor loss increases during the high slip braking process. Use this function under conditions of duty timefactors of 5% ED or less and braking times of 90 seconds or less. Braking time varies depending on the loadinertia and motor characteristics.• The configured deceleration time is ignored during the high slip braking process. To stop motors in accordancewith the configured deceleration time, set L3-04 = 4 [Decel Stall Prevention Selection = Overexcitation/HighFlux].• High slip braking cannot be used to perform deceleration at user-defined speeds. To perform deceleration atuser-defined speeds, use the overexcitation deceleration function.• Motors cannot be reaccelerated during the high slip braking process until the motor has stopped completely andthe Run command is input again.• High slip braking and the KEB Ride-Thru function cannot be used simultaneously. If both functions areenabled, oPE03 [Multi-Function Input Setting Err] is detected.■ Overexcitation DecelerationOverexcitation deceleration is used to quickly decelerate motors without connecting braking resistors to the drive.Overexcitation deceleration enables motors to be stopped more quickly than with normal ramp to stop processes.Overexcitation deceleration generates significant braking torque through motor overexcitation by increasingexcitation current during deceleration.The deceleration time can be adjusted for overexcitation deceleration by specifying the deceleration speed.Reacceleration of motors can also be performed during deceleration. Entering the Run command duringoverexcitation deceleration cancels overexcitation deceleration and the drive reaccelerates to the specified speed.To enable this function, set L3-04 =4, 5 [Decel Stall Prevention Selection = Overexcitation/High Flux,Overexcitation/High Flux 2].When L3-04 = 4 , motors decelerate for the currently valid deceleration time [C1-02, C1-04, C1-06, or C1-08].Increase the deceleration time when ov [Overvoltage] occurs.When L3-04 = 5, the drive decelerates using the [C1-02, C1-04, C1-06, or C1-08] while adjusting thedeceleration rate to keep the DC bus voltage at the level set to L3-17 [DC Bus Reg Level]. The actual stoppingtime will be longer or shorter than the set deceleration time depending on the motor characteristics and the loadinertia.Notes on Overexcitation Deceleration• Do not use Overexcitation Deceleration in combination with a braking resistor option.• Do not use Overexcitation Deceleration for the following applications. Connect a braking resistor to the driveinstead of using Overexcitation Deceleration.– Frequent repetition of sudden decelerations– Continuous regenerative loads– Low inertia machines– Machines that have no tolerance for torque ripples• Motor loss increases during overexcitation deceleration. Use this function under conditions of duty time factorsof 5% ED or less and braking times of 90 s or less. Braking time varies depending on the load inertia and motorcharacteristics.• Overexcitation deceleration can be used with OLV control and CLV control, but cannot provide as significanteffect as V/f Control because it needs to secure torque accuracy.• The following functions are disabled during braking using Overexcitation Deceleration 2, depending on thecontrol mode combined.– Hunting Prevention Function (V/f Control Mode)– Torque Limit Speed Control (Open Loop Vector Control Mode)
