Functions
8.15 Brake functions
Control Units CU240S
8-88 Operating Instructions, 11/2006, A5E00766042B AA
8.15.2.3 Dynamic braking
Data
Parameter range: P1237
Warnings: A0535
Faults: F0022
Function chart number: -
Description
For several motor applications, in certain operating states, the motor can regenerate.
Examples of these applications include:
● Cranes
● Traction motors
● Conveyor belts which transport loads downwards.
When the motor is in the regenerative mode, the energy from the motor is fed back into the
DC link of the motor through the inverter. This means that the DC link voltage increases and
when the maximum threshold is reached, the inverter is shutdown (tripped) with fault F0002.
This shutdown (trip) can be avoided by using dynamic braking. Contrary to DC and
compound braking, this technique requires that an external braking resistor is installed.
The advantages of dynamic resistor braking include:
● The regenerative energy is not converted into heat in the motor.
● It is significantly more dynamic and can be used in all operating states (not only when an
OFF command is output).
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a
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Figure 8-60 Connecting the chopper (braking) resistor
The braking energy in the DC link is converted into heat when dynamic braking is activated
(enabled using P1237). The energy is converted into heat using the voltage-controlled
chopper resistor (ballast resistor). When regenerative energy is fed back to the DC link and
in consequence the DC link threshold V
DC, Chopper
is exceeded, then the chopper resistor is
switched in using an electronic semiconductor switch.
Switch-in threshold of the chopper resistor:
If P1254 = 0:
0210P213.1V213.1V
plysuplineChopper,DC
⋅⋅=⋅⋅=
Otherwise:
1242r98.0V
Chopper,DC
⋅=
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