KEB is an acronym for Kinetic Energy Backup. If the drive detects a power loss or momentary power loss, it will quickly decelerate the motor. The drive uses regenerative energy from the motor to keep the main circuit operating. When you return power during motor deceleration, the drive returns operation to the status before the power loss. The KEB Ride-Thru function is different than other functions for continuous operation. If the drive detects momentary power loss, the motor will ramp to stop. It will not coast to stop. This function is applicable for applications in which it is necessary to prevent materials from running out, for example control for film and fiber lines.
The KEB Ride-Thru function has 4 methods of operation. Parameter L2-29 [Kinetic Energy Backup Method] sets the method.
When you use the KEB Ride-Thru function with one drive, set L2-29 = 0, 1 [Single Drive KEB Ride-Thru 1, Single Drive KEB Ride-Thru 2].
If deceleration in coordination with more than one drive is necessary, for example textile machinery line systems, set L2-29 = 2, 3 [System KEB Ride-Thru 1, System KEB Ride-Thru 2].
Table 1. KEB Ride-Thru Function Operation Method
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L2-29
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Kinetic Energy Backup Method
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Operation
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Configuration Precautions
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0
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Single Drive KEB Ride-Thru 1
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The drive uses regenerative energy from the motor to keep the DC bus voltage at the level set in L2-11 [KEB DC Bus Voltage Setpoint] while it adjusts the rate of deceleration.
The KEB operation continues while the drive adjusts the deceleration rate with the setting of C1-09 [Fast Stop Time].
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-
Set C1-09 correctly to prevent Uv1 [DC Bus Undervoltage] and ov [Overvoltage].
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If the drive detects Uv1 during the KEB operation, decrease the value set in C1-09.
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If the drive detects ov during the KEB operation, increase the value set in C1-09.
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1
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Single Drive KEB Ride-Thru 2
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The drive uses information about the inertia of the connected machinery to find the deceleration rate necessary to keep the DC bus voltage at the level set in parameter L2-11.
The drive uses system inertia to calculate the deceleration time. You cannot adjust this value.
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-
If the drive detects Uv1 during the KEB operation, increase the setting value of L3-20 [DC Bus Voltage Adjustment Gain] and L3-21 [OVSuppression Accel/Decel P Gain].
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If the drive detects ov during the KEB operation, decrease the setting values of L3-20 and L3-21.
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2
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System KEB Ride-Thru 1
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The drive does not monitor the DC bus voltage. The drive decelerates at the KEB deceleration time set in L2-06.
Use L2-06 to set the time necessary to decelerate from the current frequency reference to 0 Hz. More than one drive can decelerate and keep a constant speed ratio between drives.
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Use the dynamic braking option with System KEB Ride-Thru 1.
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3
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System KEB Ride-Thru 2
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The drive uses the KEB deceleration time set in L2-06 to decelerate and it also monitors the DC bus voltage.
If the voltage level increases, the drive momentarily holds the frequency to prevent an ov before it continues to decelerate.
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If you cannot use the dynamic braking option, use System KEB Ride-Thru 2.
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