Siemens Sinamics G120P Operating Instructions Manual page 472

Technical specifications
11.2 General data
Reduction of the output current as a function of the installation altitude
Figure 11-2
Figure 11-3
Using an isolating transformer to reduce transient overvoltages according to IEC 61800-5-1
This drops overvoltage category III to overvoltage category II, thereby reducing the
requirements for insulation capacity of the air. Additional voltage derating (reduction of the
input voltage) is not required if the following framework conditions are observed:
● The isolating transformer must be fed from a low-voltage or medium-voltage network and
must not be powered directly from a high-voltage supply system.
● The isolating transformer may be connect to one or more cabinet units.
● The cables between the isolating transformer and the cabinet unit(s) must be routed in
such a manner as to rule out direct lightening strike, i.e. overland lines must not be used.
● The following types of system are permissible:
– TN systems with grounded star point (no grounded outer conductor).
– IT systems (operation with a ground fault must be restricted to the shorted possible time).
472
Reduction of the output current as function of the installation altitude for size GX
Reduction of the output current as function of the installation altitude for size HX
Inverter cabinet units
Operating Instructions, 12/2014, A5E32923362A