Danfoss VLT Programming Manual page 48

Parameter Description
2-15 Brake Check
Option: Function:
Select type of test and monitoring function to
check the connection to the brake resistor, or
whether a brake resistor is present, and then
display a warning or an alarm in the event of a
fault. The brake resistor disconnection function is
tested during power-up. However the brake IGBT
test is performed when there is no braking. A
warning or trip disconnects the brake function.
The testing sequence is as follows:
1. The DC link ripple amplitude is measured
for 300ms without braking.
2. The DC link ripple amplitude is measured
for 300ms with the brake turned on.
3. If the DC link ripple amplitude while
braking is lower than the DC link ripple
amplitude before braking + 1 %. Brake
check failed, return a warning or alarm.
4. If the DC link ripple amplitude while
braking is higher than the DC link ripple
amplitude before braking + 1 %. Brake
check OK.
[0] Off Monitors brake resistor and brake IGBT for a short-
circuit during operation. If a short-circuit occurs, a
*
warning appears.
[1] Warning Monitors brake resistor and brake IGBT for a short-
circuit, and to run a test for brake resistor
disconnection during power-up
[2] Trip Monitors for a short-circuit or disconnection of the
brake resistor, or a short-circuit of the brake IGBT.
If a fault occurs the frequency converter cuts out
while displaying an alarm (trip locked).
[3] Stop and Monitors for a short-circuit or disconnection of the
trip brake resistor, or a short-circuit of the brake IGBT.
If a fault occurs the frequency converter ramps
down to coast and then trips. A trip lock alarm is
displayed.
[4] AC brake
NOTE
Remove a warning arising in connection with Off [0] or
Warning [1] by cycling the mains supply. The fault must be
corrected first. For Off [0] or Warning [1], the frequency
converter keeps running even if a fault is located.
®
VLT HVAC Drive Programming Guide
2-16 AC brake Max. Current
Range:
100.0 %
2-17 Over-voltage Control
Option:
[0]
[2]
NOTE
The ramp time is automatically adjusted to avoid tripping of
the frequency converter.
®
MG.11.CB.02 - VLT is a registered Danfoss trademark
Function:
[Application Enter the maximum permissible
*
dependant] current when using AC brake to
avoid overheating of motor
windings. The AC brake function is
available in Flux mode only (FC 302
only).
Function:
Over-voltage control (OVC) reduces the risk of the
frequency converter tripping due to an over
voltage on the DC link caused by generative power
from the load.
Disabled No OVC required.
Enabled Activates OVC.
*
3 3
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