Siemens SINAMICS G130 Engineering Manual page 332

SINAMICS G150
Engineering Information
DC link precharging with SINAMICS G150 parallel converters with power outputs of ≤ 1500 kW
Because the DC links of the two partial converters are coupled to one another, the precharging principle described
demands that both partial converters are connected simultaneously to the supply system. Otherwise, the precharging
rectifiers and precharging resistors of the partial converter connected first would have to precharge the entire DC link.
These components are not thermally dimensioned for this type of operation and would therefore be overloaded or
even destroyed.
To ensure that both converter sections are simultaneously connected to the supply system, it is essential to equip the
G150 parallel connections with a main contactor or a circuit breaker. These components are therefore provided as
standard in SINAMICS G150 parallel converterss. Only in this way the converter's internal sequence control can
ensure that the DC links are correctly precharged by simultaneously energizing the main contactors or circuit
breakers.
SINAMICS G150 parallel converters with power outputs of 1750 kW – 2150 kW
These SINAMICS G150 parallel converters have two rectifiers which are identical in design to thyristor-based S120
Basic Line Modules. The firing angle of the rectifier thyristors is varied in order to precharge the DC link (phase angle
control principle). For this purpose, the firing angle is increased continuously over about 1 s.
This precharging principle does not essentially require the use of circuit breakers. However, in order to maintain
consistency within the SINAMICS G150 spectrum of parallel converters, these units are also equipped with two circuit
breakers as standard.
SINAMICS G150 parallel converters with power outputs of 2400 kW – 2700 kW
These SINAMICS G150 parallel converters have two rectifiers which are identical in design to the diode-based S120
Basic Line Modules in frame size GD. DC link precharging is performed dissipative via resistors. In order to
precharge the DC link, the two rectifiers are connected to the line supply by means of precharging contactors and
precharging resistors. When the DC link is precharged, the main contactors are closed and the precharging
contactors opened again.
DC link precharging with SINAMICS G150 parallel converters with power outputs of 2400 kW – 2700 kW
This precharging principle essentially requires two circuit breakers. These components are therefore provided as
standard in SINAMICS G150 parallel connections.
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