This delay prevents an unintentional restart if the drive detects that mains is back at an acceptable level, but
not being consistently back.
The purpose of this function is to handle mains drop in low inertia applications, where the drive must continue
running to make a ride-through by reducing the speed until the grid returns to full voltage. During the voltage
drop, the speed ramps down using parameter 3-81 Quick Stop Ramp Time until voltage returns. After that, nor-
mal ramp up is used. The DC link is not regulated since this is not possible in a low-inertia application without
any generative power in the motor/load. The selection is valid for IPM and SPM motors in Flux. To ensure that
the function is activated, set parameter 14-11 Mains Failure Voltage Level higher than the expected voltage drop
level. The quick ramp down must be set fast enough to endure a significant load drop to allow the control to
run at reduced voltage, and it must be slow enough not to reach standstill before voltage returns - if possible. If
speed reaches 0, it stays there until voltage returns and ramps up. If an alarm is required at standstill, it can be
programmed in the SLC. An optional delay, set in parameter 40-14 Mains Loss Duration, can be activated before
ramping up to bypass and ripple on the DC link when power returns.
Parameter 14-11 Mains Fault Voltage Level
Table 709: Parameter 14-11 Mains Fault Voltage Level
14-11 Mains Fault Voltage Level
Default value: Size related
Parameter type: Range, 100 - 800 V
Change during operation: True
This parameter defines the threshold voltage at which the function in parameter 14-10 Mains Failure is activated. Select the detec-
tion level depending on the supply quality. For a supply of 380 V, set parameter 14-11 Mains Fault Voltage Level to 342 V. This results
in a DC detection level of 462 V (parameter 14-11 Mains Fault Voltage Level x 1.35).
N O T I C E
Converting from VLT 5000 to FC 300: Even though the setting of the mains voltage at mains fault is the same for VLT 5000 and FC
300, the detection level is different. Use the following formula to obtain the same detection level as in VLT 5000: Parameter 14-11
Mains Fault Voltage Level (VLT 5000 level) = value used in VLT 5000 x1.35/sqrt(2).
Parameter 14-12 Response to Mains Imbalance
Table 710: Parameter 14-12 Response to Mains Imbalance
14-12 Response to Mains Imbalance
Default value: [0] Trip lock
Change during operation: True
N O T I C E
Make sure that the setting in parameter 0-03 Regional Setting matches the actual grid.
Operation under severe mains imbalance conditions reduces the lifetime of the motor. Conditions are considered severe if the mo-
tor is operated continuously near nominal load (for example, a pump or a fan running near full speed). Select the level of operation
when mains imbalance conditions occur. Options [5] Fast trip lock to [7] Fast warning are based on a principle which enures detec-
tion of a missing mains phase within 2 s and responds according to the selection. See parameter 14-17 Fast Mains Phase Loss and
parameter 14-18 Fast Mains Phase Loss Min Power. A minimum load on the drive of 2% nominal power is required for detection of
missing mains phase.
AU275636650261en-000101 / 130R0334 | 457Danfoss A/S © 2022.12
Parameter Descriptions
VLT AutomationDrive FC 301/302
Programming Guide
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