GE AF-650 GP Design And Installation Manual page 78

Application Setup Examples
Figure 6.22
NOTE!
Make sure the resistor is designed to handle the required
braking time.
Size
3 x 200–240 V
3 x 380–480 V*
3 x 525–600 V
3 x 525–690 V
Table 6.22
* Power size dependent
NOTE!
Check that the brake resistor can cope with a voltage of
410 V, 850 V, 975 V or 1,130 V.
The recommended brake resistance guarantees that the
adjustable frequency drive is able to brake at the highest
braking torque (M ) of 160%. The formula can be
br(%)
written as:
2
U dc x
100
R rec Ω =
P motor x M br x η DRIVE x
(%)
η is typically at 0.90
motor
η is typically at 0.98
DRIVE
For 200 V, 480 V and 600 V adjustable frequency drives,
R at 160% braking torque is written as:
rec
107780
V R rec
200 : = Ω
P motor
375300
Ω 1)
V R rec
480 : =
P motor
428914
Ω 2)
V R rec
480 : =
P motor
630137
V R rec
600 : = Ω
P motor
832664
690 V : R rec = Ω
P motor
1) For adjustable frequency drives ≤ 10 hp [7.5 kW] shaft
output
2) For adjustable frequency drives 11–75 kW shaft output
TM
AF-650 GP Design and Installation Guide
Brake active
390 V (UDC)
810 V/795 V
943 V
1084 V
η
motor
DET-767A
The max. permissible load on the brake resistor is stated as
a peak power at a given intermittent duty cycle and can
be calculated as:
The brake resistance is calculated as shown:
2
U
dc
R
Ω =
br
P
peak
where
P = P x M [%] x η
peak motor br motor
As can be seen, the brake resistance depends on the
intermediate circuit voltage (U
The AF-650 GP brake function is settled in four areas of
line power.
Warning before cut-out
405 V
840 V/828 V
965 V
1109 V
NOTE!
If a brake resistor with a higher ohmic value is selected,
the 160% braking torque may not be achieved because
there is a risk that the adjustable frequency drive cuts out
for safety reasons.
NOTE!
If a short circuit in the brake transistor occurs, power
dissipation in the brake resistor is only prevented by using
a line switch or contactor to disconnect the line power for
the adjustable frequency drive. (The contactor can be
controlled by the adjustable frequency drive).
NOTE!
Do not touch the brake resistor, as it can get very hot
during/after braking. The brake resistor must be placed in
a secure environment to avoid fire risk.
CAUTION
Unit size 4x to 6x adjustable frequency drives contain more
than one brake chopper. Consequently, use one brake
resistor per brake chopper for those frame sizes.
x η [W]
DRIVE
).
dc
Cut-out (trip)
410 V
850 V/855 V
975 V
1130 V
6-23
6 6