Operating instructions

2-12 Brake Power Limit (kW)
Range: Function:
Application
dependent
*
[Application
dependant]
Set the monitoring limit of the brake
power transmitted to the resistor.
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:
P
resistor
=
390
2
× dutytime
R
× 120
[W]
For 380 - 480 V
units
P
resistor
=
778
2
× dutytime
R
× 120
[W]
For 380 - 500 V
units
P
resistor
=
810
2
× dutytime
R
× 120
[W]
For 575 - 600 V
units
P
resistor
=
943
2
× dutytime
R
× 120
[W]
This parameter is only active in frequency converters with an
integral dynamic brake.
2-13 Brake Power Monitoring
Option: Function:
This parameter is only active in frequency
converters with an integral dynamic brake.
This parameter enables monitoring of the power
to the brake resistor. The power is calculated on
the basis of the resistance (par. 2-11 Brake
Resistor (ohm), the DC link voltage, and the
resistor duty time.
[0]
* Off No brake power monitoring is required.
[1] Warning Activates a warning on the display when the
power transmitted over 120 s exceeds 100% of
the monitoring limit (par. 2-12 Brake Power Limit
(kW)).
The warning disappears when the transmitted
power falls below 80% of the monitoring limit.
[2] Trip Trips the frequency converter 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 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 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 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 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 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 discon-
nection 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
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 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 frequen-
cy converter keeps running even if a fault is located.
2-16 AC brake Max. Current
Range: Function:
100.0 % * [Application
dependant]
Enter the maximum permissible
current when using AC brake to avoid
overheating of motor windings. The AC
brake function is available in Flux
mode only (FC 302 only).
Parameter Description
VLT
®
HVAC Drive Programming Guide
MG.11.CA.02 - VLT
®
is a registered Danfoss trademark 47
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