YASKAWA CIMR-VU BA0001 Technical Manual page 219

This setting rarely needs to be changed.
When setting L2-05 is lower than the default setting, be sure to install an AC reactor option to the input side of the power
supply to prevent damage to drive circuitry.
n Kinetic Energy Backup (KEB) Function
In case of a power loss, the KEB function can decelerate the motor and use the rotational energy of the machine to backup/
maintain the drive DC bus for a certain period of time. This allows the drive to continue running without interrupting the output
power during a momentary power loss. Once the power is restored, the drive smoothly returns to the same operational state
before the power loss occurred. The KEB function supports two different operation modes.
KEB 1
In this mode the drive decelerates the motor based on the deceleration time set in parameter L2-06/C1-09 in order to keep the
DC bus voltage level high. When the power supply returns, it uses the time set to L2-07 or the selected acceleration time to
accelerate back to the frequency reference.
(H1-oo = 65 or 66)
Note: If L2-06 is set to 0.0 s, C1-09 is used instead. If L2-07 is set to 0.0 s, the drive reaccelerates using the selected acceleration time.
Use this method with setting parameters L2-06 and L2-07 if multiple drives must decelerate but still keep the speed ratio
between the drives constant during power loss. In this case, a braking resistor is required in order to avoid overvoltage trips.
KEB 2
In this mode the drive decelerates the motor by calculating the energy of the rotating system. The deceleration rate is
continuously adjusted so that the DC bus voltage meets the level set in parameter L2-11. The rotational energy is estimated
using the parameters L3-24 and L3-25. When the power supply returns, the drive accelerates back to the frequency reference
using the selected acceleration time.
Activation and Deactivation of the KEB Function
The KEB function requires parameter L2-01 to be set to 1 or 2 and a digital input has to be configured for the KEB 1
(H1-oo = 65/66) or KEB 2 (H1-oo = 7A/7B) command. The input has to be enabled during KEB.
KEB Ride-Thru 1 (N.C.)/2 (N.O.) on page 192
details on setting the KEB input commands.
The KEB function is automatically activated when one of the conditions below becomes true.
• The DC bus voltage falls below the level set in parameter L2-05. The KEB input has to be set within 50 ms after the KEB
function was activated, or the drive will assume the power supply has returned and attempt to restart.
• The input programmed for KEB 1 or 2 is activated. This input should be triggered by an external undervoltage detection
relay.
The KEB function ends when one of the conditions below become true.
• The KEB input was released or
• The function was activated by DC bus voltage detection and no KEB input was set within 50 ms after the KEB activation.
Figure 5.80 shows a wiring example for triggering the KEB function at power loss using digital input S6.
YASKAWA ELECTRIC SIEP C710606 18F YASKAWA AC Drive – V1000 Technical Manual
OFF
KEB Ride-Thru
Output
frequency
Figure 5.79 KEB Ride-Thru Timing Diagram for Multiple Drives
and Refer to Setting 7A/7B: KEB Ride-Thru 2 (N.C./N.O.) on page 194
ON OFF
L2-06 L2-07
5.8 L: Protection Functions
Refer to Setting 65/66:
for
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