Eaton PowerXL DC1 20 Series Installation Manual page 50

2 Engineering
2.7 Braking resistances
~
Mains
=
46
In the case of units with a frame size of FS2 or FS3, brake resistor DX-BR3-
100 (P = 200 W) can be inserted underneath the heat sink. In addition,
D
parameter P-34 must be set to a value of 1 in order to protect against thermal
overloads (braking chopper activated with electronic overload protection).
Figure 15: DC1 variable frequency drive with a frame size of FS2
and a DX-BR3-100 brake resistor
It is often difficult to specify a suitable brake resistor for specific applications.
This is due to the fact that not all of the application conditions required for
sizing will be available when the engineering stage starts. Because of this,
and as a simplification, brake resistors are instead usually classified for two
load groups:
• Low duty: Low load with short braking duration and low duty factor
(up to about 25 %), e.g., for horizontal conveyors and handling
equipment for bulk cargo and general cargo, end carriages, sliding doors,
and turbomachinery (centrifugal pumps, fans).
• High duty: High load with long braking duration and high duty factor
(at least 30 %), e.g., for elevators, downhill conveyors, winders,
centrifuges, flywheel motors, and large fans.
R
B
DC+ BR
=
Figure 16: Braking cycle, fast motor stop with external brake resistor
DC1...20... and DC1...OE1 Variable Frequency Drives 02/20 MN040059EN www.eaton.com
Motor
M
P
PEAK
~
P
RD
n
P
t t
Brems OFF
t
C
t
t
t
Brems