Overload Relay - 3RU range Switch position indicator and test function STOP button Selector switch for manual/automatic reset Screw connection or Spring-clamp versions Impulse voltage resistance 6 kV Insulation voltage 690V Surface or DIN-rail stand-alone mounts available, see 706-1699 etc The 3RU21 thermal overload relays up to 80 A have been designed for current-sensitive protection of loads with normal starting. These thermal overload relays for use with Sirius Size S0 & S00 Contactors Note Screw terminals can only be used with screw terminal overloads and spring terminals can only be used with spring terminal overloads. Approvals CE, UL, CSA Siemens Sirius Range Contactor & Control Relays Siemens control gear for feeders up to 5.5kW. The complementary nature of the devices allows fast and simple assembly, for example, of motor starters and reversers. A perfect match between contactors, overloads, circuit breakers and accessories for the same power ratings provides a uniform panel appearance and the standard widths with no side-by-side mounting derating allows for space saving.