Danfoss VLT AutomationDrive EZ FC 321 Programming Manual page 267

VLT® AutomationDrive EZ FC 321
Programming Guide
Op- Name Description
tion
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. The funcitonality is the same as in [1] Ctrl. ramp-down, except in this option a reset is necessary for starting up
ramp-
after power-up.
down,
trip
[3] Coast- Centrifuges can run for 1 hour without supply. In those situations, it is possible to select a coast function at
ing mains interruption, together with a flying start, which occurs when the mains is restored.
[4] Kinetic Kinetic back-up ensures that the drive keeps running as long as there is energy in the system due to the inertia
back- from motor and load. This is done by converting the mechanical energy to the DC link and maintaining control
up 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.
U [V]
DC
U
DC
SP-11*1.35
n [RPM]
Ref
Illustration 74: Kinetic Back-up
A
B
C
The DC level during [4] Kinetic backup equals parameter 14-11 Mains Fault Voltage Level x 1.35. If the mains does
not return, U
coasts. If the mains returns while in kinetic back-up mode, U
Voltage Level x 1.35. This is detected in 1 of the following ways:
•
If U
DC
• If the speed is above the reference. This is relevant if the mains comes back at a lower level than before, for
example parameter 14-11 Mains Fault Voltage Level x 1.35 x 1.02. This does not fulfil the criterion in point 1,
and the drive tries to reduce U
speed. This cannot be done as the mains cannot be lowered.
• If running mechanically. The same mechanism as in point 2 applies, but the inertia prevents the speed from
going above the reference speed. This leads to the motor running mechanically until the speed is above
the reference speed and the situation in point 2 occurs. Instead of waiting for that criterion, point 3 is intro-
duced.
[5] Kinetic The difference between kinetic back-up with and without trip is that the latter always ramps down to 0 RPM
bac-up, and trips, regardless of whether mains returns or not. The function does not detect if mains returns. This is the
trip reason for the relatively high level on the DC link during ramp-down.
Danfoss A/S © 2021.08
A B C D E A
t [S]
t [S]
Normal operation
Mains failure
Kinetic back-up
is maintained as long as possible by ramping the speed down towards 0 RPM. Finally, the drive
DC
> parameter 14-11 Mains Fault Voltage Level x 1.35 x 1.05.
to parameter 14-11 Mains Fault Voltage Level x 1.35 by increasing the
DC
Parameter Descriptions
D Mains return
E Normal operation: Ramping
increases above parameter 14-11 Mains Fault
DC
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