Notes on selection
The following conditions should be maintained when selecting the overvoltage protection:
- The limit voltage of the overvoltage protectionVRRM55 must not exceed the highest periodic and permissible peak blocking voltage of the power semiconductor to be protected.
- The rated supply voltage of the overvoltage protection must not be exceeded.
- Commutation overvoltages of the converter that periodically occur must remain below the response voltage of the overvoltage protection. The energy absorption capability of the selected overvoltage protection should be checked. A distinction must be made between two operating cases:
- A transformer is shut down under no-load conditions
- A transformer is shut down under load
Detailed notes on configuration, standards and connection of the overvoltage protection are provided in the Operating Instructions, on the DVD-ROM supplied with Catalog D 23.1 or in the Internet under
http://support.automation.siemens.com/WW/view/en/18260008/130000.