Siemens SINAMICS S120 Manual page 122

Line-side power components
4.7 Active Interface Modules Chassis-2
Figure 4-37 Active Interface Module Chassis-2 pre-charging input circuit
Precharging contactor
The precharging contactor must be able to conduct the maximum precharging current for
approx. 1 second and be able to switch ohmic-capacitive loads.
To protect against overvoltage when opening, the contactor should be equipped with a
varistor, corresponding to the manufacturer's recommendations.
The precharging contactor is controlled via terminal -X9: VL1, VL2 of the Active Line Modules
Chassis-2. The switching capacity of the floating relay contact is described here: X9 terminal
strip (Page 227).
An additional normally closed (NC contact) of the precharging contactor must be routed to
terminal -X47:1 to guarantee the feedback signal. The 24 V DC supply can be taken from
terminal strip -X42.
The following contactors are recommended:
• For a version with one precharging resistor for each phase, a Sirius 3RT2027 is
recommended.
• For a version with two precharging resistors connected in parallel for each phase, a Sirius
3RT2037 contactor is recommended.
• For a version with three precharging resistors connected in parallel for each phase, a Sirius
3RT2037 contactor is recommended.
120
Air-cooled chassis power units
Equipment Manual, 06/2020, 6SL3097-5AE00-0BP3