The Siemens 3UG5512-2BR20 is a line monitoring relay that checks three-phase supplies for phase failure, phase sequence reversal, and asymmetry. It monitors 3 x 160-690 V AC at 15-70 Hz and switches two changeover contacts via spring-loaded terminals.
The 160-690 V AC input range covers low-voltage European and North American three-phase systems (230/400/480/600 V) without external PTs. Two changeover contacts let the relay signal a fault to a PLC and drop a line contactor independently. Spring-loaded terminals accept 0.2-2.5 mm² conductors, strip length around 8-10 mm. The housing dimensions (126 x 112 x 36 mm) fit a standard DIN-rail footprint; factor in clearance for the spring-cage actuation tool above and below.