Derating As A Function Of The Installation Altitude - Siemens PM330 Hardware Installation Manual

Technical specifications
6.3 Derating data
6.3.2

Derating as a function of the installation altitude

Voltage
The insulation clearances within the inverter are measured for surge voltages in accordance
with overvoltage category III in compliance with EN 60664-1 for installation altitudes up to
2000 m above sea level.
Use of an isolating transformer to reduce transient overvoltages to IEC 61800--5--1
By using the isolating transformer, overvoltage category III is reduced to overvoltage
category II. As a result, the requirements placed on the insulating capability of air are
reduced. An additional (input) voltage derating is not necessary if the following basic
conditions are met:
● The isolation transformer must be fed from a low-voltage or medium-voltage network; it
must not be supplied directly from a high-voltage network.
● The isolating transformer may be connect to one or more inverters.
● The cables between the isolating transformer and the inverters must be routed in such a
manner as to rule out a direct lightning strike, i.e. it is not permissible for overland lines to
be used.
● The following supply system types are permissible:
– TN supply systems with grounded star point (no grounded phase conductor)
– IT supply systems (operation with a ground fault must be limited to the shortest time
Note
The connected motors and power components must be considered separately.
100
possible)
Hardware Installation Manual, 12/2018, A5E32844552B AF
Power Module PM330