T
ta
tc
tb
to
ta
tc
tb
to
ta
130BA167.10
Load
Time
Speed
Figure 3.32 Typical Braking Cycle
Cycle time (s)
Braking duty cycle at 100%
torque
Braking duty cycle at over torque
(150/160%)
380
–
500 V
N90K-N160
600
Continuous
10%
N200-N250
600
Continuous
10%
P315-P800
600
40%
10%
525–690 V
N55K-N315, P355-P400
600
40%
10%
P500-P560
600
40%
10%
P630-P1M0
600
40%
10%
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:
Rbr Ω =
Udc
2
Ppeak
where
P
peak
=P
motor
xM
br
[%]xη
motor
xη
VLT
[W]
As can be seen, the brake resistance depends on the intermediate circuit voltage (U
dc
).
Size
Brake active
Warning before cut-out
Cut-out (trip)
FC 302
3x380–500 V*
810 V/795 V
84 V/828 V
850 V/855 V
FC 302
3x525–690 V
1084 V
1109 V
1130 V
Table 3.19 Brake Limits
* Power size dependent
Product Introduction
Design Guide
54
Danfoss A/S © Rev. 2014-02-10 All rights reserved.
MG34S222
3
3
Summary of Contents for VLT AutomationDrive FC 300
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