5-80 AHF Cap Reconnect Delay
Range:
Function:
25 s
*
[1 - 120 s]
Guarantees a minimum off-time for
the capacitors. The timer starts
once the AHF capacitor disconnects
and has to expire before the output
is allowed to be on again. It only
turns on again if the frequency
converter power is 20–30%.
6.1.3 DC-link Compensation Disabling
NOTICE
To prevent resonances in the DC link, disable the
dynamic DC-link compensation by setting
parameter 14-51 DC-Link Compensation
to
[0] Off
.
The FC series includes a feature which ensures that the
output voltage is independent of any voltage fluctuation in
the DC link, for example, caused by fast fluctuation in the
mains supply voltage. Sometimes, this dynamic compen-
sation can produce resonances in the DC link and should
then be disabled. Typical cases are where VLT
®
Advanced
Harmonic Filter AHF 005/AHF 010 is used on supply grids
with high short circuit ratio. Fluctuations can often be
recognized by increased acoustic noise and, in extreme
cases, by unintended tripping.
14-51 DC-Link Compensation
Option:
Function:
The rectified AC-DC voltage in the
frequency converter's DC link is
associated with voltage ripples.
These ripples can increase in
magnitude with increased load.
These ripples are undesirable
because they can generate current
and torque ripples. A compensation
method is used to reduce these
voltage ripples in the DC link. In
general, DC-link compensation is
recommended for most
applications, but pay attention
when operating in field weakening
as it can generate speed oscillations
at the motor shaft. In field
weakening, turn off DC-link
compensation.
[0]
Off
Disables DC-link compensation.
[1]
On
Enables DC-link compensation.
Programming
VLT
®
Advanced Harmonic Filter AHF 005/AHF 010
48
Danfoss A/S © 05/2019 All rights reserved.
MG80C602
6
6
Summary of Contents for AHF 010
Page 2: ......
