Lenze i550

14.1.1 Use of a brake resistor
For braking operaon, oponally the brake chopper integrated in the inverter (brake transis-
tor) can be used.
Precondions
In order that the integrated brake chopper is acvated in the braking operaon, one of the
following braking methods must be set in 0x2541:001 (P706.01):
•
"Brake resistor [0]"
•
"Brake resistor + RFGS [2]"
•
"Brake resistor + IMB + RFGS [4]"
In the default seng of 0x2541:001 (P706.01), the integrated brake chopper is not acvated
in the brake operaon!
Details
•
The brake resistor required is to be connected to terminals R
B1
and R
B2
of the inverter.
•
In 0x2541:001 (P706.01), addionally the stopping funcon for the deceleraon ramp
funcon generator can be set when the brake resistor is controlled, in order to avoid over-
voltage disconnecon in the case of lower deceleraon mes.
•
In the default seng and with a disabled inverter and an error status ("Error acve"), the
brake chopper is switched o. This behaviour can be changed in 0x2541:006 (P706.06).
Example: In a DC-bus connecon with several inverters, only one brake resistor is used. It
is connected to the most powerful inverter in the DC-bus connecon. This inverter then
serves to change the behaviour so that inverter disable and/or an error does not cause a
switch-o of the brake chopper.
Internal protecve funcon
The following protecve funcon prevents the brake chopper from being switched on perma-
nently, e.g. due to too high voltages or wrong sengs:
•
The brake chopper is switched o if it was switched on over a period of 4 s.
•
If the DC-bus voltage again falls below the voltage threshold for braking operaon, the
brake chopper can again be switched on for maximally 4 s without interrupon.
Brake resistor monitoring
The inverter calculates and monitors the thermal load of the brake resistor to ensure that the
brake resistor will not be overloaded.
A correct calculaon required the following sengs according to the data on the nameplate of
the brake resistor:
•
0x2550:002 (P707.02): Resistance value
•
0x2550:003 (P707.03): Rated power
•
0x2550:004 (P707.04): Maximum thermal load
The calculated thermal load is not displayed in 0x2550:007 (P707.07).
The brake resistor monitoring is designed with two stages:
•
If the calculated thermal load exceeds the warning threshold set in 0x2550:008 (P707.08)
(default seng: 90 %), the response set in 0x2550:010 (P707.10) takes place (default set-
ting: "Warning"). The warning status will be reset if the thermal load falls below the warn-
ing threshold - 20 %.
•
If the calculated thermal load exceeds the warning threshold set in 0x2550:009 (P707.09)
(default seng: 100 %), the response set in 0x2550:011 (P707.11) takes place (default set-
ting: "Fault"). The error status will be reset if the thermal load falls below the error thresh-
old - 20 %.
Addional funcons
Brake energy management
Use of a brake resistor
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