12.9 L: Protection Functions
972 YASKAWA SIEPC71061737D GA800 Drive Technical Reference
■ L2-04: Powerloss V/f Recovery Ramp Time
No.
(Hex.)
Name Description
Default
(Range)
L2-04
(0488)
Powerloss V/f Recovery
Ramp Time
Sets the time for the drive output voltage to go back to correct voltage after completing speed
searches.
Determined by o2-04, C6-01
(0.0 - 5.0 s)
Sets the time for voltage to recover from 0 V to the value set in E1-05 [Maximum Output Voltage].
■ L2-05: Undervoltage Detection Lvl (Uv1)
No.
(Hex.)
Name Description
Default
(Range)
L2-05
(0489)
Undervoltage Detection Lvl
(Uv1)
Sets the voltage at which a Uv1 [DC Bus Undervoltage] fault is triggered or at which the KEB
function is activated. Usually it is not necessary to change this setting.
Determined by o2-04 and
E1-01
(200 V Class: 150 - 210 V,
400 V Class: 300 - 420 V)
NOTICE: Damage to Equipment. When you set this parameter to a value lower than the default, you must install an AC reactor on
the input side of the power supply. If you do not install an AC reactor, it will cause damage to the drive circuitry.
Note:
If the low voltage detection level is near the lower limit value of L2-05, the drive will detect Uv1 during KEB Ride-Thru operation. Do not
set the value too low when you use the KEB Ride-Thru function.
■ L2-06: Kinetic Energy Backup Decel Time
No.
(Hex.)
Name Description
Default
(Range)
L2-06
(048A)
Expert
Kinetic Energy Backup
Decel Time
Sets the deceleration time during KEB operation used to decrease the maximum output frequency to
0.
0.0 s
(0.0 - 6000.0 s)
Set L2-29 = 2 or 3 [Kinetic Energy Backup Method = System KEB Ride-Thru 1 or System KEB Ride-Thru 2] to
enable this function. When L2-29 = 1, 2 , 3 [Kinetic Energy Backup Method = Single Drive KEB Ride-Thru 2, System
KEB Ride-Thru 1, System KEB Ride-Thru 2] and you do KEB Auto-Tuning, the drive will automatically set this
value.
Sets the deceleration time necessary to decelerate from the frequency reference to 0 Hz when the drive detects a
momentary power loss. If a Uv1 [DC Bus Undervoltage] fault occurs during KEB operation, decrease the
deceleration time. If an ov [Overvoltage] fault occurs, increase the deceleration time.
• L2-06 = 0
The drive automatically decreases C1-09 [Fast Stop Time] to the base value to keep the DC bus voltage above the
low voltage detection level. The drive ignores L2-02 [Momentary Power Loss Ride-Thru Time] in this condition.
• L2-06 ≠ 0
As shown in Figure 12.129, the frequency reference decelerates to the KEB frequency level as specified by the
deceleration rate set in L2-06 and then returns to the initial frequency reference as specified by C1-01 [Acceleration
Time 1]. The drive uses the setting value of the KEB frequency rate as shown in the this formula to set the KEB
frequency level:
KEB frequency level = Output frequency before power loss × (1 - (L2-02)/ (L2-06))
Figure 12.129 Kinetic Energy Backup Decel Time
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