3PR3 resistors are equipped with cast iron resistor elements type WE, which are installed in a steel sheet housing. Ceramic strips hold and insulate the resistor elements inside the housing. A heat shield separates the resistor zone from the terminal zone. Connecting pieces screwed to the resistor elements supported on ceramic hold strips are used for connecting the cables. Each resistor element can be provided with a connection. Changes or supplements regarding the connections are easy, even retroactively.
The 3PR3 Siemens system is the successor of the 3PR2 system. The elements are identical and exchangeable.