2-12 Brake Power Limit (kW)
Range:
Function:
U
br
is the DC voltage where the brake
resistor is active, depending on the unit
as follows:
T2 units: 390 V
T4 units: 778 V
T5 units: 810 V
T6 units: 943 V/1099 V for D – F frames
T7 units: 1,099 V
NOTICE!
If R
br
is not known or if T
br
is
different from 120 s, the practical
approach is to run the brake
application, readout
16-33 Brake
Energy /2 min
and then enter + 20%
in
2-12 Brake Power Limit (kW)
.
2-13 Brake Power Monitoring
Option:
Function:
This parameter is only active in adjustable
frequency drives with an integral dynamic brake.
This parameter enables monitoring of the power
to the brake resistor. The power is calculated
based on the resistance (
), the DC link voltage, and the
resistor duty time.
[0] Off
No brake power monitoring required.
[1] Warning
Activates a warning on the display when the
power transmitted over 120 s exceeds 100% of
the monitoring limit (
).
The warning disappears when the transmitted
power falls below 80% of the monitoring limit.
[2] Trip
Trips adjustable frequency drive and displays an
alarm when the calculated power exceeds 100%
of the monitoring limit.
[3] Warning
and trip
Activates both of the above, including warning,
trip and alarm.
If power monitoring is set to
[0] Off
or
[1] Warning
, the
brake function remains active, even if the monitoring limit
is exceeded, possibly leading to thermal overload of the
resistor. It is also possible to generate a warning via a
relay/digital output. 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: 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
alarm in the event of a fault.
NOTICE!
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
300 ms without braking.
2.
The DC link ripple amplitude is measured for
300 ms with the brake turned on.
3.
If the DC link ripple amplitude while braking is
lower than the DC link ripple amplitude
before b 1%:
Brake check has failed by
returning a warning or alarm.
4.
If the DC link ripple amplitude while braking is
higher than the DC link ripple amplitude
before b 1%:
Brake check is OK.
[0] Off Monitors brake resistor and brake IGBT for a short-
circuit during operation. If a short-circuit occurs,
Warning 25 appears.
NOTICE!
Remove a warning arising with
[0] Off
or
[1] Warning
by
cycling the line power supply. The fault must be
corrected first. For
[0] Off
or
[1] Warning
, the adjustable
frequency drive keeps running even if a fault is located.
This parameter is only active in adjustable frequency drives
with an integral dynamic brake.
Programming
Instruction Manual
60
Danfoss A/S © Rev. 2014-02-07 All rights reserved.
MG37A222
6
6
Summary of Contents for VLT AutomationDrive FC 302
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