Danfoss VLT Series Programming Manual page 51

Parameter Description
3.4.2 2-1* Brake Energy Funct.
Parameter group for selecting dynamic braking parameters.
Only valid for drives with brake chopper.
2-10 Brake Function
3 3
Option:
[0] Off
*
[1] Resistor
brake
[2] AC brake
2-11 Brake Resistor (ohm)
Range:
Size [
related 65535.00
*
Ohm]
2-12 Brake Power Limit (kW)
Range:
Size [ 0.001 -
related 2000.000
*
kW]
50
VLT
Function:
Available selections depend on 1-10 Motor
Construction:
[0] Asynchron:
[0] off
[1] Resistor brake
[2] AS brake
[1] PM non salient:
[0] off
[1] Resistor brake
No brake resistor installed.
Brake resistor incorporated in the system, for
dissipation of surplus brake energy as heat.
Connecting a brake resistor allows a higher DC
link voltage during braking (generating
operation). The Resistor brake function is only
active in frequency converters with an integral
dynamic brake.
AC Brake will only work in Compressor Torque
mode in 1-03 Torque Characteristics.
Function:
5.00 - Set the brake resistor value in Ohms.
This value is used for monitoring the
power to the brake resistor in
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 two
decimals, use 30-81 Brake Resistor
(ohm).
Function:
2-12 Brake Power Limit (kW) is the expected
average power dissipated in the brake
resistor over a period of 120s. It is used as
the monitoring limit for 16-33 Brake
Energy /2 min and thereby specifies when a
warning/ alarm is to be given.
To calculate 2-12 Brake Power Limit (kW),
the following formula can be used.
U br 2 V × t br s
P br,avg W =
R br Ω × T br s
MG.11.CC.02 - VLT
®
HVAC Drive Programming Guide
2-12 Brake Power Limit (kW)
Range:
2-13 Brake Power Monitoring
Option:
[0] Off
*
[1] Warning
[2] Trip
[3] Warning
and trip
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%).
®
is a registered Danfoss trademark
Function:
P is the average power dissipated in
br,avg
the brake resistor, R is the resistance of
br
the brake resistor. t is the active breaking
br
time within the 120 s period, T
U is the DC voltage where the brake
br
resistor is active. This depends on the unit
as follows:
T2 units: 390V
T4 units: 778V
T5 units: 810V
T6 units: 943V / 1099V for D – F frames
T7 units: 1099V
NOTE
If R is not known or if T
br br
from 120s, the practical approach is to
run the brake application, readout
16-33 Brake Energy /2 min and then
enter this + 20% in 2-12 Brake Power
Limit (kW).
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
(2-11 Brake Resistor (ohm), the DC link voltage,
and the resistor duty time.
No brake power monitoring is required.
Activates a warning on the display when the
power transmitted over 120 sec. exceeds 100%
of the monitoring limit (2-12 Brake Power Limit
(kW)).
The warning disappears when the transmitted
power falls below 80% of the monitoring limit.
Trips the frequency converter and displays an
alarm when the calculated power exceeds
100% of the monitoring limit.
Activates both of the above, including
warning, trip and alarm.
.
br
is different