4.4.14.2 Reduction of the charging currents
The two levels for the UP and the UP reset threshold are preset according to the
power unit.
In case of short voltage dips where the inverter is not / only slightly loaded (e.g.
modulation off or motor in no-load operation), the dip in the DC link voltage may be
so small that the precharge circuit is not reactivated.
If the power recovery occurs in this state, there can be extremely high currents in
the DC link.
These currents can only be reduced / avoided if the voltage level at which error UP
is triggered or precharge is activated is increased.
This is possible with is18 UP error level and is19 UP reset level .
Since internal switching power supplies depend on the DC link voltage, the UP
threshold can only be lowered slightly.
➢ Between is18 UP error level and is19 UP reset level must
always be at a sufficient distance (for 400V devices at least
60V).
4.4.14.3 Error triggering
Only if the DC link voltage falls below the value of is18 during activated modulation,
error "6: ERROR underpotential" (display in ru01) is triggered. The same applies to
error 123: ERROR PUready (power unit ready - signal inactive)
Otherwise, only ru04 supply unit state changes back to the state "5: phase failure“
and the state machine cannot be beyond state "2: switch on disable“ (st12 state
machine display).
If a low DC link voltage also shall trigger an error, if the modulation is not released
can be parameterized by pn77 E.UP2 stopping mode.
Function with programming of pn77 to 0: fault“: an undervoltage error is triggered if
ST is set and after waiting for the delay time (pn 76 E.UP2 delay time) ru04 supply
unit state has not reached the state "4: run“.
The software ST (Bit 0 and 1 of co31 internal control word ) and the state of the
STO inputs is considered as ST.
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