The 3RA2120-4BH27-0AP0: It ships as a pre-matched assembly: the supplied contactor is 3RT2027-2AP00, the circuit-breaker is 3RV2021-4BA20, plus the link module 3RA2921-2AA00 and busbar adapter 8US1251-5NT11 — the BOM is coordinated for the 7.5 kW rating, so you don't need to size each component separately. The overload release is thermal bimetallic (Trip Class 10), and the short-circuit trip is magnetic — standard protection for motor starting duty where the inrush lasts under 10 seconds.
Snap-on busbar mounting and clearance envelope
This starter snaps directly onto 60 mm busbar systems — no DIN rail adapter needed — and is designed specifically for that busbar pitch. The enclosure measures 165 mm deep, 45 mm wide, and 260 mm high. Clearance requirements: 50 mm above, 20 mm forward, 0 mm behind, 10 mm below, and 20 mm at the sides — these are the minimum gaps for ventilation and wiring access. Mounting position must be vertical — the bimetallic overload relies on natural convection for accurate thermal replication, so horizontal mounting shifts the trip curve.
Spring-loaded terminals and environmental limits
Both the main current circuit and the auxiliary/control circuit use spring-loaded terminals — no screw torque to verify, just strip and push in solid or ferruled stranded wire. Operating temperature range is -20 to +60 °C, with storage and transport limits from -50 to +80 °C — the starter can sit in an unheated warehouse through winter and still commission in a warm cabinet. The substance prohibitance date of 10/01/2009 confirms RoHS compliance for the European market.