System Integration; Brake Resistor Calculation; Brake Set-Up; Calculation Of Brake Resistor Resistance - Danfoss VLT Brake Resistor MCE 101 Design Manual

System Integration

4 System Integration

4.1 Brake Resistor Calculation

To ensure the optimal selection of brake resistor for a
given application, its inertia and braking profile
calculations are required.
This chapter explains the calculations required to obtain
values for optimal selection of brake resistor for a given
application.

4.1.1 Brake Set-up

The following sections use expressions and abbreviations
related to the brake set-up in Illustration 4.1.
VLT
η
= 0.98
INV
U
DC
η
= 0.9
motor
P
motor
Illustration 4.1 Brake Set-up
4.1.2 Calculation of Brake Resistor
Resistance
To prevent the frequency converter from cutting out for
protection when the motor brakes, select resistor values on
the basis of the peak braking power and the intermediate
circuit voltage:
2
Udc
R br = Ω
P peak
The brake resistor performance depends on the DC-link
voltage (U ).
dc
MG90O202
Design Guide
P
peak
P
I
avg
termo
R
br
P
b, max
P
peak,mec.
Danfoss A/S © Rev. 05/2014 All rights reserved.
U is the voltage, where the brake is activated. The FC-
dc
series brake function is settled depending on the mains
supply.
DC-link Voltage (U ), FC 51
dc
Size [V] Brake active
[V]
FC 51 1x200-240 390
FC 51 3x200-240 390
FC 51 3x380-480,
770
1.5-4.0 kW
FC 51 3x380-480,
705-770
5.5-15 kW
FC 51 3x380-480,
770
18.5-22 kW
Table 4.1 DC-link Voltage (U ), FC 51
dc
1) Adjustable with 2-14 Brake Voltage Reduce
DC-link Voltage (U ), FC 102
dc
Brake
Size [V] active
[V DC]
FC 102 3x200-240 390
FC 102 3x380-480 778
1) 943
FC 102 3x525-600
2) 1099
FC 102 3x525-600
FC 102 3x525-690 1099
Table 4.2 DC-link Voltage (U ), FC 102
dc
1) Enclosure types A, B, C
2) Enclosure types D, E, F
DC-link Voltage (U ), FC 202
dc
Brake
Size [V] active
[V DC]
FC 202 3x200-240 390
FC 202 3x380-480 778
1) 943
FC 202 3x525-600
FC 202 3x525-600 2) 1099
FC 202 3x525-690 1099
Table 4.3 DC-link Voltage (U ), FC 202
dc
1) Enclosure types A, B, C
2) Enclosure types D, E, F
Warning Cut out
before cut (trip) [V]
out [V]
410 410
410 410
800 800
1) 800 800
800 800
High Over
voltage voltage
warning alarm
[V DC] [V DC]
405 410
810 820
965 975
1109 1130
1109 1130
High Over
voltage voltage
warning alarm
[V DC] [V DC]
405 410
810 820
965 975
1109 1130
1109 1130
15
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