Danfoss VLT AutomationDrive FC 301 Programming Manual page 62

Parameter Descriptions
2-07 Parking Time
Range:
3.3.2 2-1* Brake Energy Funct.
3 3
Parameter group for selecting dynamic brake parameters.
Only valid for frequency converters with brake chopper.
2-10 Brake Function
Option:
[0] Off
*
[1] Resistor
brake
[2] AC brake Improves braking without using a brake resistor.
2-11 Brake Resistor (ohm)
Range:
Size [ 5.00 -
related 65535.00
*
Ohm]
2-12 Brake Power Limit (kW)
Range:
Size [ 0.001 -
related 2000.000
*
kW]
60
VLT
Function:
Function:
No brake resistor is installed.
A brake resistor is 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.
This parameter controls an overmagnetization of
the motor when running with a generatoric load.
This function can improve the OVC function.
Increasing the electrical losses in the motor
allows the OVC function to increase the braking
torque without exceeding the overvoltage limit.
NOTICE
The AC brake is not as efficient as
dynamic braking with resistor.
+
AC brake is for VVC mode in both open
and closed loop.
Function:
Set the brake resistor value in Ω. 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:
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 /2 min and
thereby specifies when a warning/alarm is
to be given.
Danfoss A/S © 01/2018 All rights reserved.
®
AutomationDrive FC 301/302
2-12 Brake Power Limit (kW)
Range:
2-13 Brake Power Monitoring
Option:
[0] Off
*
[1] Warning
[2] Trip
[3] Warning
and trip
Function:
To calculate parameter 2-12 Brake Power
Limit (kW), the following formula can be
used.
2
U V × t s
br br
P W =
br, avg R Ω × T s
br br
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
br
breaking time within the 120 s period,
T .
br
U is the DC voltage where the brake
br
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 /2 min
and then enter this
+ 20% in parameter 2-12 Brake
Power Limit (kW).
Function:
This parameter is only active in frequency
converters with a 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.
No brake power monitoring required.
Activates a warning on the display when the
power transmitted during the duty time 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.
Trips the frequency converter and shows an
alarm when the calculated power exceeds 100%
of the monitoring limit.
Activates both of the above, including warning,
trip, and alarm.
is
br
MG33MO02