11.9 L: Protection Functions
946 YASKAWA ELECTRIC SIEP C710617 05F YASKAWA AC Drive GA700 Technical Manual
Table 11.70 KEB Ride-Thru Function Operation Method
L2-29
Kinetic
Energy
Backup
Method
Operation Configuration Precautions
0 Single Drive
KEB Ride-Thru
1
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].
• 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.
1 Single Drive
KEB Ride-Thru
2
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.
• 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 value of L3-20 and L3-21.
2 System KEB
Ride-Thru 1
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.
Use the dynamic braking option with System KEB
Ride-Thru 1.
3 System KEB
Ride-Thru 2
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.
If you cannot use the dynamic braking option, use
System KEB Ride-Thru 2.
■ 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.
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