
•
•
•
•
[1] Ctrl. ramp-down
[2] Ctrl. ramp-down, trip
[5] Kinetic back-up, trip
[7] Kin. back-up, trip w recovery
N O T I C E
This parameter cannot be changed while the motor is running.
Parameter 14-10 Mains Failure
is typically used where short mains interruptions (voltage dips) are present. At 100% load and a short
voltage interruption, the DC voltage on the main capacitors drops quickly. For larger drives, it only takes a few milliseconds before
the DC level drops to about 373 V DC, and the IGBTs cut off and lose the control of the motor. When mains is restored, and the IGBTs
start again, the output frequency and voltage vector do not correspond to the speed/frequency of the motor, and the result is nor-
mally an overvoltage or overcurrent, mostly resulting in a trip lock.
Parameter 14-10 Mains Failure
can be programmed to avoid this
situation. Select the function according to which the drive must act when the threshold in
parameter 14-11 Mains Fault Voltage Level
is reached.
Op-
tion
Name
Description
[0]*
No
func-
tion
The drive does not compensate for a mains interruption. The voltage on the DC link drops quickly and motor
control is lost within milliseconds to seconds. This situation results in a trip lock.
[1]
Ctrl.
ramp-
down
Control of the motor remains with the drive, and the drive performs a controlled ramp down from
parameter
14-11 Mains Fault Voltage Level
. If
parameter 2-10 Brake Function
is
[0] Off
or
[2] AC brake
, the ramp follows the
overvoltage ramping. If
parameter 2-10 Brake Function
is
[1] Resistor Brake
, the ramp follows the setting in
pa-
rameter 3-81 Quick Stop Ramp Time
. This selection is useful in pump applications, where the inertia is low and
the friction is high. When mains is restored, the output frequency ramps the motor up to the reference speed. If
the mains interruption is prolonged, the controlled ramp down may bring the output frequency down to
0 RPM, and when the mains is restored, the application is ramped up from 0 RPM to the previous reference
speed via the normal ramp-up. If the energy in the DC link disappears before the motor is ramped to 0, the
motor is coasted.
Limitation:
See the introduction text in this parameter.
[2]
Ctrl.
ramp-
down,
trip
The functionality is the same as in
[1] Ctrl. ramp-down
, except in this option a reset is necessary for starting up
after power-up.
[3]
Coast-
ing
Centrifuges can run for 1 hour without supply. In those situations, it is possible to select a coast function at
mains interruption, together with a flying start, which occurs when the mains is restored.
[4]
Kinetic
back-
up
Kinetic back-up ensures that the drive keeps running as long as there is energy in the system due to the inertia
from motor and load. This is done by converting the mechanical energy to the DC link and maintaining control
of the drive and motor. This can extend the controlled operation, depending on the inertia in the system. For
fans, it is typically several seconds; for pumps up to 2 s; and for compressors only for a fraction of a second.
Many industry applications can extend controlled operation for many seconds, which is often enough time for
the mains to return.
e3
0b
c9
18
.1
0
U
SP-11*1.35
Ref
n [RPM]
t [S]
A B C D E
A
DC
U
DC
[V]
t [S]
Illustration 83: Kinetic Back-up
AU275636650261en-000101 / 130R0334
454 | Danfoss A/S © 2022.12
Parameter Descriptions
VLT AutomationDrive FC 301/302
Programming Guide