Danfoss VLT FC 102 Programming Manual page 74

Parameter Descriptions
2-11 Brake Resistor (ohm)
Range:
Size
related 65535.00
*
Ohm]
3 3
2-12 Brake Power Limit (kW)
Range:
Size
related 2000.000 kW]
*
72
Function:
Set the brake resistor value in Ω.
[ 5.00 -
This value is used for monitoring
the power to the brake resistor in
parameter 2-13 Brake Power
Monitoring. This parameter is only
active in frequency converters with
an integral dynamic brake.
Use this parameter for values
without decimals. For a selection
with 2 decimals, use
parameter 30-81 Brake Resistor
(ohm).
Function:
[ 0.001 - Parameter 2-12 Brake Power Limit
(kW) is the expected average power
dissipated in the brake resistor over
a period of 120 s. It is used as the
monitoring limit for
parameter 16-33 Brake Energy
Average and thereby specifies when
a warning/alarm is to be given.
To calculate parameter 2-12 Brake
Power Limit (kW), the following
formula can be used.
2
U V × t
br br
P W =
br, avg
R Ω × T
br br
P is the average power
br,avg
dissipated in the brake resistor, R
is the resistance of the brake
resistor. t is the active breaking
br
time within the 120 s period, T
U is the DC voltage where the
br
brake resistor is active. This
depends on the unit as follows:
T2 units: 390 V
T4 units: 810 V
T5 units: 810 V
T6 units: 943 V/1099 V for D – F
frames
T7 units: 1099 V
NOTICE
If R is not known, or if T
br
different from 120 s, the
practical approach is to run
the brake application, read
parameter 16-33 Brake Energy
Average and then enter this
+ 20% in parameter 2-12 Brake
Power Limit (kW).
Danfoss A/S © 10/2019 All rights reserved.
®
VLT HVAC Drive FC 102
2-13 Brake Power Monitoring
Option:
[0]
*
s
[1]
s
br
.
br
[2]
[3]
[4]
[5]
is
[6]
br
[7]
[8]
[9]
[10]
[11]
[12]
[13]
Function:
NOTICE
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 based on
the resistance (parameter 2-11 Brake
Resistor (ohm)), the DC-link voltage,
and the resistor duty time.
Off No brake power monitoring is
required.
If power monitoring is set to [0] Off
or [1] Warning, 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%).
Warning 120s Activates a warning when the
power transmitted over 120 s
exceeds 100% of the monitoring
limit (parameter 2-12 Brake Power
Limit (kW)).
The warning disappears when the
transmitted power drops below
80% of the monitoring limit.
Trip 120s Trips the frequency converter and
shows an alarm when the
calculated power exceeds 100% of
the monitoring limit.
Warning & trip Activates both of the above,
120s including warning, trip, and alarm.
Warning 30s
Trip 30s
Warning & trip
30s
Warning 60s
Trip 60s
Warning & trip
60s
Warning 300s
Trip 300s
Warning & trip
300s
Warning 600s
M0010001