The Z characteristic means it trips between 2 and 3 times the rated current — designed for semiconductor protection and sensitive electronic loads where standard B or C curves would allow too much through before opening.
Three-pole format covers three-phase circuits — typically feeding a motor starter, a small distribution sub-panel, or a bank of control transformers. The Z curve makes it a common choice downstream of a UPS or in DC link protection where the inrush is low but the fault rise time is fast.