Danfoss VLT AutomationDrive FC 300 Design Manual page 56

Product Introduction
Load
3 3
Speed
Figure 3.32 Typical Braking Cycle
380–500 V
N90K-N160
N200-N250
P315-P800
525–690 V
N55K-N315, P355-P400
P500-P560
P630-P1M0
Table 3.18 Braking at High Overload Torque Level
Danfoss offers brake resistors with duty cycle of 5%, 10% and 40%. If a 10% duty cycle is applied, the brake resistors are
able to absorb braking energy for 10% of the cycle time. The remaining 90% of the cycle time is used on dissipating excess
heat.
Make sure the resistor is designed to handle the required braking time. The maximum permissible load on the brake resistor
is stated as a peak power at a given intermittent duty cycle. The brake resistance is calculated as shown:
2
U dc
Rbr Ω =
Ppeak
where
P =P xM
peak motor
As can be seen, the brake resistance depends on the intermediate circuit voltage (U
Size
FC 302
3x380–500 V*
FC 302
3x525–690 V
Table 3.19 Brake Limits
* Power size dependent
54
ta tc tb to ta tc tb
T
Cycle time (s)
[%]xη xη [W]
br motor VLT
Brake active
810 V/795 V
1084 V
Danfoss A/S © Rev. 2014-02-10 All rights reserved.
Design Guide
to ta
Time
Braking duty cycle at 100%
600 Continuous
600 Continuous
600
600
600
600
Warning before cut-out
84 V/828 V
1109 V
Braking duty cycle at over torque
torque (150/160%)
40%
40%
40%
40%
).
dc
Cut-out (trip)
850 V/855 V
1130 V
10%
10%
10%
10%
10%
10%
MG34S222