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Functions
7.7 Protection functions
Inverter with CU240B-2 and CU240E-2 Control Units
180
Operating Instructions, 07/2010, FW 4.3.2, A5E02299792B AA
Protecting the motor and inverter against overvoltage
The V
DCmax
controller prevents – as far as is technically possible – the DC link voltage from
reaching critical levels.
The V
DCmax
controller is not suitable for applications in which the motor is permanently in the
regenerative mode, e.g. in hoisting gear or when large flywheel masses are subject to
braking. For applications such as these, you must select an inverter that is equipped with a
braking resistor (Power Module PM240 plus external braking resistor) or can feed energy
back into the line supply (Power Modules PM250 and PM260).
There are two different groups of parameters for the V
DCmax
controller, depending on whether
the motor is being operated with V/f control or vector control.
Table 7- 20 V
DCmax
controller parameters
Parameter for
V/f control
Parameter for
vector control
Description
p1280 = 1
p1240 = 1
V
DC
controller or V
DC
monitoring configuration(factory setting:
1)1: Enable V
DCmax
controller
r1282
r1242
V
DCmax
controller switch-on level
Shows the value of the DC-link voltage above which the V
DCmax
controller is active
p1283
p1243
V
DCmax
controller dynamic factor (factory setting: 100 %) scaling
of the control parameters P1290, P1291 and P1292
p1290
p1250
V
DCmax
controller proportional gain (factory setting: 1)
p1291
p1251
V
DCmax
controller reset time (factory setting p1291: 40 ms,
factory setting p1251: 0 ms)
p1292
p1252
V
DCmax
controller rate time (factory setting p1292: 10 ms, factory
setting p1252: 0 ms)
p1294
p1254
V
DCmax-
controller automatic recording ON-signal level(factory
setting p1294: 0, factory setting p1254: 1)Activates or
deactivates automatic detection of the switch-on levels of the
V
DCmax
controller.
0: Automatic detection disabled
1: Automatic detection enabled
p0210
p0210
Device connection voltage
If p1254 or p1294 = 0, the inverter uses this parameter to
calculate the intervention threshold of the V
DCmax
controller.
Set this parameter to the actual value of the input voltage.
For more information about this function, see the List Manual (function diagrams 6320 and
6220).