Siemens sitop industrial ups modules 24v siemens 6ep1931 2fc21 a 40a 24v dc din rail mounting uninterruptible power supply ups with a 24v dc input the high reliability ups unit can easily cope with critical network conditions and protect systems against mains problems and problems on the dc side siemens 6ep1931 2fc21 sitop industrial ups 40a 24vdc