Danfoss VLT AutomationDrive FC 300 Design Manual page 152

FC 300 Design Guide
The monitoring limit is a product of the maximum
duty cycle (120 sec.) and the maximum
power of the brake resistor at that duty cycle.
See the formula below.
For 200 - 240 V units:
For 380 - 480 V units
For 380 - 500 V units
For 575 - 600 V units
2-13 Brake Power Monitoring
Option:
*
Off
Warning
Trip
Warning and Trip
Function:
This parameter is only active in frequency
converters with an integral dynamic brake.
Allows monitoring of the power to the brake
resistor. The power is calculated on the basis of
the resistor ohm value (par. 2-11), the DC link
voltage, and the resistor duty time. If the power
transmitted over 120 s exceeds 100% of the
monitoring limit (par. 2-12) and Warning [1] is
selected, a warning appears on the display.
The warning disappears if the power goes below
80%. If the calculated power exceeds 100%
of the monitoring limit and Trip [2] is selected
in par. 2-13 Power Monitoring, the frequency
converter trips and displays an alarm.
If power monitoring is set to Off [0] or Warning
[1], the brake function remains active, even if the
monitoring limit is exceeded. This may lead to
thermal overload of the resistor. It is also possible
to have a warning via a relay/digital outputs.
The measuring accuracy of the power monitoring
depends on the accuracy of the resistance of
the resistor (better than ± 20%).
2-15 Brake Check
Option:
*
Off
Warning
Trip
Stop and Trip
Function:
This parameter is only active in frequency
converters with an integral dynamic brake.
default setting ( )
*
152
How to Programme
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display text [ ] value for use in communication via serial communication port
MG.33.B4.02 - VLT is a registered Danfoss trademark
Enables the intergration of a test and monitor
function, which displays a warning or an alarm. On
power-up, the functions is tested for disconnection
of the brake resistor. The test is carried out during
braking. Testing for disconnection of the IGBT,
however, is carried out when there is no braking.
A warning or trip disconnects the brake function.
The testing sequence is as follows:
The DC link ripple amplitude is measured
1.
for 300 ms without braking.
The DC link ripple amplitude is measured for
2.
300 ms with the brake turned on.
If the DC link ripple amplitude while braking
3.
is lower than the DC link ripple amplitude
before braking + 1 %. Brake check failed,
return a warning or alarm.
If the DC link ripple amplitude while braking
4.
is higher than the DC link ripple amplitude
before braking + 1 %. Brake check OK
Select Off [0]. This function still monitors whether
the brake resistor and the brake IGBT short-circuit
during operation. If so, a warning appears. Select
Warning [1] to monitor the brake resistor and
brake IGBT for to short-circuiting. During power-up
disconnection of the brake resistor is checked.
NB!:
Remove a warning arisen in connection
with Off [0] or Warning [1] by cycling the
mains supply. The fault must be corrected
first. With Off [0] or Warning [1], the frequency
converter keeps running even if a fault is located. In
the case of Trip [2], the frequency converter cuts
out while displaying an alarm (trip locked). This
happens if the brake resistor is short-circuited, is
disconnected, or if the brake IGBT is short-circuited.
2-17 Over-voltage Control
Option:
*
Disabled
Enabled (not at stop)
Enabled
Function:
The Over-voltage Control is selected to reduce the
risk for the drive to trip by an over voltage on the
DC link caused by generative power from the load.
Enabled (not at stop), means that OVC is active
except when stopping with a stop signal applied.
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