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Resistor Braking
Braking Chopper
NBRA-6xx
Installation and Start-up Guide for NBRA-6xx
The deceleration time of an AC drive can be decreased by using
resistor braking. For this, the frequency converter has to be equipped
with a braking chopper and a braking resistor.
The standard braking choppers and braking resistors available for the
ACS 600 units are given in Table 2-1.
The choppers and the resistors are rated so that the power equal to the
short-term overload capacity of the ACS 600 can be handled during
braking. The short-term overload capacity for a Normal Use rated
ACS 600 is 110 % of the rated output power (current), and, for a
Heavy-duty Use rated ACS 600, 150 % of the rated output power
(current).
The NBRA-6xx Braking Choppers are optional devices for ACS 600
Family frequency converters.
The chopper connects the braking resistor to the intermediate circuit of
the frequency converter whenever the voltage in the intermediate
circuit exceeds the maximum limit.
The maximum limit is equal to 1.21 · 1.35 · U
on the chopper voltage selection (see Chapter 3 – Voltage Selection
and Mechanical Installation). With the selection 400V, U
with the selection 500V, U
(NBRA-66x), U
is 690V. Energy consumption by resistor losses
1max
lowers the voltage until the resistor can be disconnected. This limit is
equal to 1.19 · 1.35 · U
a fast deceleration of the drive typically causes the voltage to rise in the
intermediate circuit.
Note: Drive Parameter 20.5 (20.7 for ACP 600) OVERVOLTAGE CTRL
must be set to OFF to enable chopper operation.
The chopper control board supervises system status and detects
failures such as:
• braking resistor and resistor cable short circuits
• chopper (IGBT) short circuit
• chopper control board failure.
Chapter 2 – Overview
is 500 V; with the selection >500V
1max
. The energy generated by the motor during
1max
. U
is dependent
1max
1max
is 415 V;
1max
2-1
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