The 1SAZ321401R1005: Solid-state overload relays replace the bi-metallic element with a current transformer and electronic trip curve, which is what lets the same physical module cover a 45-63 A span in one part number instead of forcing a heater-coil change-out per motor. In the typical motor branch the relay sits downstream of the short-circuit protective device and upstream of the contactor — it does not break short-circuit current, it manages sustained overload and phase-loss events on the contactor it commands.
Reading the 45-63 A rating
The 45-63 A range listed on this part decides motor fit; setting is dialled inside that band per the relay face rather than requiring a heater coil per motor size. Set-point lives inside that window — the installer dials the exact motor FLA on the relay face, so one order code covers the band rather than forcing a unique heater coil per motor size.
Mounting and panel-side handling
Pass the motor conductors through the relay's integrated CT windows in the direction the marking indicates — reversing them defeats the current sensing on a solid-state unit in a way a bi-metallic strip would tolerate. Wire the output contacts into the contactor coil string per the same loop the upstream short-circuit protection already coordinates with; the relay's job is to command a stop, not to clear a fault.
Sourcing posture
1SAZ321401R1005 is specified into the BOM against this order code and quoted to order; an RFQ against this exact MPN is the cleanest path when the panel drawing already names it.