Resistor Braking; What This Chapter Contains; Braking Choppers And Resistors With The Acsm1-204; Braking Choppers - ABB ACSM1 Hardware Manual

Resistor braking

What this chapter contains

This chapter describes how to select, protect and wire braking choppers and
resistors. The chapter also contains the technical data.

Braking choppers and resistors with the ACSM1-204

The regen supply module is used for feeding braking energy back to the network,
and thus a braking resistor is usually not needed. However, if it is possible that the
braking capacity of the regen supply module is temporarily exceeded, a braking
resistor may be installed to increase braking capacity.
Note: Braking resistor(s) can also be installed to the ACSM1-04 drive(s) connected
to the same dc-bus.

Braking choppers

ACSM1-204 regen supply modules have a built-in braking chopper as standard
equipment. The regen supply module controls the DC-bus voltage and keeps it
within limits by default. However, if the braking capacity of the regen supply module
is exceeded during braking, the DC-bus voltage increases.
When the braking chopper is enabled and a resistor is connected, the chopper starts
conducting when the DC-link voltage of the regen supply module reaches 780 V. The
maximum braking power is achieved at 840 V.
The braking chopper of a regen supply module or drive connected to the DC bus can
be used to increase the braking capacity of the system to, for example, cover peaks
in the braking capacity.

Braking resistor selection

Pre-selected resistors are available from ABB as shown in the table below. If the
listed resistor is not sufficient for the application, a custom resistor can be selected
within the limits imposed by the internal braking chopper of the ACSM1-204. The
following rules apply:
• The resistance of the custom resistor must be at least R
capacity with different resistance values can be calculated from the following
formula
where UDC equals 840 V.
2
U
DC
P
max <
R
. The braking power
min
Resistor braking
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