YASKAWA GA800 Technical Reference page 965

Kinetic Energy
L2-29
Backup Method
0 Single Drive KEB The drive uses regenerative energy from the motor to keep the DC bus
Ride-Thru 1 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].
1 Single Drive KEB The drive uses information about the inertia of the connected machinery
Ride-Thru 2 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.
2 System KEB Ride- The drive does not monitor the DC bus voltage. The drive decelerates at
Thru 1 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.
3 System KEB Ride- The drive uses the KEB deceleration time set in L2-06 to decelerate and
Thru 2 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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KEB Ride Thru Start
When L2-01 = 3, 4, 5 [Power Loss Ride Through Select = Kinetic Energy Backup: L2-02, Kinetic Energy Backup:
CPU Power, Kinetic Energy Backup: DecelStop], the drive starts the KEB operation immediately after it detects a
momentary power loss. When one of these conditions occur, the drive will activate KEB Ride-Thru:
• KEB Ride-Thru 1 set for the MFDI terminal becomes enabled (terminal is deactivated when H1-xx = 65 or terminal
is activated when H1-xx = 66).
The drive uses the mode selected L2-29 [Kinetic Energy Backup Method] to start KEB operation.
• KEB Ride-Thru 2 set for the MFDI terminal becomes enabled (terminal is deactivated when H1-xx = 7A or terminal
is activated when H1-xx = 7B).
The drive automatically starts Single KEB Ride-Thru 2 and it ignores the setting of L2-29.
• The DC bus voltage is less than the level set in L2-05 [Undervoltage Detection Lvl (Uv1)].
The KEB operation will start as specified in L2-29.
Note:
If you try to set KEB Ride-Thru 1 and 2 to the MFDI terminals at the same time, it will trigger oPE03 [Multi-Function Input Setting Err].
n this example, the drive detects that the DC bus voltage is less than the level set in L2-05 and starts the KEB
operation. When you return power during KEB operation, the drive will continue KEB operation when the KEB Ride-
Thru is input, although the time set in L2-10 [Minimum KEB Time] expired. The motor accelerates again after you
cancel the KEB Ride-Thru.
YASKAWA SIEPC71061737D GA800 Drive Technical Reference
Table 12.66 KEB Ride-Thru Function Operation Method
Operation
Figure 12.123 KEB Operation through KEB Ride-Thru Input
12.9 L: Protection Functions
Configuration Precautions
• Set C1-09 correctly to prevent Uv1 [DC Bus Undervoltage] and ov
[Overvoltage].
• If the drive detects Uv1 during the KEB operation, decrease the value
set in C1-09.
• If the drive detects ov during the KEB operation, increase the value
set in C1-09.
• 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].
• If the drive detects ov during the KEB operation, decrease the setting
values of L3-20 and L3-21.
Use the dynamic braking option with System KEB Ride-Thru 1.
If you cannot use the dynamic braking option, use System KEB Ride-
Thru 2.
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