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Use only resistors that are specified as braking resistors. See chapter
"2.3 Braking resistor", page 17 for suitable braking resistors.
Connection of braking resistor Braking resistors with degree of protection IP65 may be installed out-
side the control cabinet in an appropriate environment in order to
decrease the temperature in the control cabinet.
The external braking resistors listed in the Accessories chapter are
shipped with an information sheet that provides details on installation.
Further procedure:
• Connect the braking resistors to the drive.
• LXM32: Check the parameter RESint_ext during commissioning.
This parameter allows you to switch between internal and external
braking resistor.
• LXM32: If you have connected an external braking resistor to an
LXM32 drive, you must set the parameters for the external braking
resistor during commissioning.
• During commissioning, test the braking resistors under realistic
conditions, see page 54.
Wire ferrules: If you use wire ferrules, use only wire ferrules with col-
lars for these terminals.
3.5.2 Rating information
To rate the braking resistor, calculate the proportion contributing to
absorbing braking energy.
An external braking resistor is required if the kinetic energy that must
be absorbed exceeds the total of the internal proportions, including
the internal braking resistor.
The energy E
var
is the square difference between the voltage before
the deceleration process and the response threshold.
The voltage prior to the deceleration process depends on the mains
voltage. The energy absorption by the DC bus capacitors is lowest
when the mains voltage is highest. In the calculation, use the values
for the highest mains voltage.
Energy absorption braking resistor Two characteristic values determine the energy absorption of the
braking resistor:
• The continuous power P
PR
is the amount of energy that can be
continuously absorbed without overloading the braking resistor.
• The maximum energy E
CR
limits the maximum short-term power
that can be absorbed.
If the continuous power was exceeded for a specific time, the braking
resistor must remain without load for a corresponding period.
The characteristic values P
PR
and E
CR
of the internal braking resistor
can be found in chapter "2 Technical Data".
See page 22 for information on assessing the electrical and mechani-
cal losses.
Example: LXM32 drive Deceleration of a rotary motor with the following data:
3 Engineering
LXM32
34
Common DC bus
MNA01M001EN, V1.01, 08.2014