•
•
•
•
Op-
tion
Name
Description
[0]
Off
No brake resistor installed.
[1]
Resistor
brake
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 drives with an integral dynamic brake.
[2]
AC brake
Improves braking without using a brake resistor. This parameter controls an overmagnetization of the mo-
tor when running with a generatoric load. This function can improve the OVC function. Increasing the elec-
trical losses in the motor allows the OVC function to increase the braking torque without exceeding the
overvoltage limit.
N O T I C E
The AC brake is not as efficient as dynamic braking with resistor. AC brake is for VVC
+
mode in both open
and closed loop.
Parameter 2-11 Brake Resistor (ohm)
Table 154: Parameter 2-11 Brake Resistor (ohm)
2-11 Brake Resistor (ohm)
Default value: Size related
Parameter type: Range, 0 - 65535 Ohm
Setup: All setups
Conversion index: 0
Data type: Uint16
Change during operation: True
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 drives 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)
.
Parameter 2-12 Brake Power Limit (kW)
Table 155: Parameter 2-12 Brake Power Limit (kW)
2-12 Brake Power Limit (kW)
Default value: Size related
Parameter type: Range, 0.001 - 2000.000 kW
Setup: All setups
Conversion index: 0
Data type: Uint32
Change during operation: True
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.
P
br, avg
W
=
U
2br
V
×
t
br
s
R
br
Ω
×
T
br
s
P
br,avg
is the average power dissipated in the brake resistor, R
br
is the resistance of the brake resistor. t
br
is the active braking time
within the 120 s period, T
br
. U
br
is the DC voltage where the brake resistor is active. This depends on the unit as follows:
T2 units: 390 V
T5 units: 810 V
T6 units: 943 V/1099 V for D enclosures
T7 units: 1099 V
N O T I C E
If R
br
is not known, or if T
br
is 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)
.
AU373327181955en-000101 / 130R1208 | 99
Danfoss A/S © 2021.08
Parameter Descriptions
VLT® AutomationDrive EZ FC 321
Programming Guide