Yaskawa F7 Drive Programming Manual - Manual (Page 126)

Programming 118
L2 Momentary Power Loss Ride-thru Function
When momentary power loss recovery is enabled (L2-01 ≠0), a speed search is executed to catch the potently spinning motor
shaft. This speed search will occur regardless of the setting of b3-01 “Speed Search Selection”.
L2-01 Momentary Power Loss Detection Selection
L2-02 Momentary Power Loss Ride-Thru Time
Setting Range: 0.0 to 25.5 Seconds
Factory Default: Model Dependent
The Drive allows different responses to momentary power losses. The setting of L2-01 determines whether the Drive attempts
to restart after a short loss of incoming AC power and for what length of time this capability remains active.
If L2-01= “0: Disabled”, the Drive detects a UV1 fault 15ms after power loss and automatic restarting is disabled. The Drive
cannot restart until the external run command is removed and the UV1 fault is reset.
If L2-01= “1: PwrL Ride Thru t”, the Drive restarts without the UV1 fault if power is returned within the time specified in L2-
02, the Momentary Power Loss Ride-thru Time. During the power loss but before the fault trip, the digital operator will display
a UV alarm. If L2-02 is set for a time longer than the control power supply can be sustained, a UV1 fault will not occur and the
Drive restarts upon the return of AC power. The time that the control power supply can be maintained varies with Drive size.
The larger the Drive is, the greater the potential ride-thru time.
If L2-01= “2: CPU Power Active”, the Drive ignores L2-02 and attempts a restart as long as the control power supply is still
able to maintain a minimal voltage level. In effect, setting L2-01= “2: CPU Power Active” (factory default) is programming the
Drive for maximum Power Loss Ride-thru. An equivalent setting is L2-01= “1: PwrL Ride Thru t”, with L2-02 set to a time
longer than the control power supply can be maintained after power is lost.
Note: The run command must be held during power loss for any power loss ride-thru capability to be possible. It is for this
reason that 3-wire control is not recommended for use with the Momentary Power Loss function.
L2-03 Momentary Power Loss Minimum Baseblock Time
Setting Range: 0.1 to 5.0 Seconds
Factory Default: Model Dependent
When momentary power loss recovery is enabled (L2-01 ≠0) the Drive will baseblock for a period of time specified by the L2-03
parameter. The baseblock time will be executed just prior to the speed search function in order to allow any residual magnetic
fields in the motor windings to decay before any new voltage is applied to the motor.
If the motor’s secondary circuit time constant is known, set L2-03= 0.7x (value of time constant). If an OC or OV fault occurs
during momentary power loss recovery, increase the setting of L2-03.
The L2-03 parameter also sets the baseblock time for the DC Injection Braking function (b1-03= “2: DC Injection to Stop”). If
an OC or OV fault occurs during DC Injection Braking to Stop, increase the setting of L2-03.
Setting Description
0 Disabled
1 Power Loss Ride Thru Time
2 CPU Power Active (factory default)