The Siemens 7SJ6-001-5EA00-0DA0 is an overcurrent relay from the 7SJ6 family, supplied at 240VAC. It sits in the Circuit Breakers, Fuses & Protection category, under Relays and Overcurrent Relays. This is the part you'd spec into a motor or feeder protection scheme where a single-phase AC control voltage is available.
What the 240VAC supply means for fit
The 240VAC control supply is the operating voltage for the relay's internal electronics and output contacts. If your panel runs a 240VAC control bus (common in North American and some European industrial installations), this relay drops right into the topology without an extra control transformer. If your control voltage is 120VAC or 24VDC, this variant won't work — you'd need a different 7SJ6 order code.