CSU20A is a small light-weight current and voltage source primarily intended to work together with the SVERKER 750/760 Relay Testing Unit when testing differential relays. Using the CSU20A together with SVERKER 750/760 gives the user two independent current sources, and the timer/measurement section in SVERKER 750/760 is used both for measuring the two outputs as well as measuring the trip time of the relay.

The Phase Selector Switch PSS750 is specifically designed to work with SVERKER 750/760 when testing three-phase relays. It is connected between SVERKER 750/760 and the relay inputs and allows the user to easily select which phase to test.