Danfoss VLT AutomationDrive FC 300 Operating Instructions Manual page 48

4 How to Programme
[1] Resistor brake
[2] AC brake
2-11 Brake Resistor (ohm)
4
Range:
50. Ohm* [5. - 32000. Ohm]
2-12 Brake Power Limit (kW)
Range:
5.000 kW* [0.001 - 500.000 kW]
For 200 - 240 V units:
For 380 - 480 V units
For 380 - 500 V units
For 575 - 600 V units
This parameter is only active in frequency converters with an integral dynamic brake.
2-13 Brake Power Monitoring
Option:
[0] * Off
[1] Warning
[2] Trip
[3] Warning and trip
If power monitoring is set to
overload of the resistor. It is also possible to generate a warning via a relay/digital outputs. The measuring accuracy of the power monitoring depends
on the accuracy of the resistance of the resistor (better than ± 20%).
48
A brake resistor is incorporated in the system, for dissipation of surplus brake energy as heat. Con-
necting 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.
Is selected to improve braking without using a brake resistor. This parameter controls an overmag-
netization 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 over voltage limit. Please note that AC brake is not as effective as
dynamic breaking with resistor.
AC brake is for VVC
Function:
Set the brake resistor value in Ohms. This value is used for monitoring the power to the brake
resistor in par. 2-13
with an integral dynamic brake.
If the selection is xxxx use this parameter. If the selection is xxx.xx, use par. 3-81
Time .
Function:
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.
390 2 ×
dutytime
P resistor =
R × 120
778 2 ×
dutytime
P resistor =
R
× 120
810 2 ×
dutytime
P resistor
=
R
× 120
943 2 ×
dutytime
P resistor
=
R × 120
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
duty time.
No brake power monitoring required.
Activates a warning on the display when the power transmitted over 120 s exceeds 100% of the
monitoring limit (par. 2-12
The warning disappears when the transmitted power falls below 80% of the monitoring limit.
Trips frequency converter and displays an alarm when the calculated power exceeds 100% of the
monitoring limit.
Off [0] or Warning [1], the brake function remains active, even if the monitoring limit is exceeded. This may lead to thermal
MG.33.AC.02 - VLT is a registered Danfoss trademark
®
VLT
+ and flux mode in both open and closed loop.
Brake Power Monitoring
. This parameter is only active in frequency converters
Brake Resistor (ohm)
Brake Power Limit (kW) ).
AutomationDrive FC 300 Operating
Instructions
Quick Stop Ramp
), the DC link voltage, and the resistor