The C6334A570 is a MicroLogic 4.3 AL electronic trip unit for the Schneider Electric ComPacT NSX400...630 molded-case circuit breaker range. It is the replaceable protection logic module that plugs into the breaker — you swap the trip unit, not the whole breaker, to change the protection profile or rating. Rated 570 A at 40 °C, it is sized for distribution feeders in the upper end of the NSX frame. The trip unit provides LSoI protection: long-time overload (L), short-time short-circuit with fixed delay (So), and instantaneous short-circuit (I). The long-time pickup (Ir) is adjustable from 250 to 570 A across nine settings, so the same unit covers a range of cable or transformer ratings without a hardware swap. Short-time pickup (Isd) adjusts from 1.5 to 10 times Ir; instantaneous pickup (Ii) is fixed at 6900 A.
Integrated earth-leakage — what Class A means on the line
This is the AL variant, meaning it carries integrated earth-leakage protection rated Class A per IEC 60755. Class A detects sinusoidal AC residual currents plus pulsating DC — the common waveform from rectified loads, VFDs, and switched-mode supplies that a plain AC-sensitive relay misses. Sensitivity (IΔn) is adjustable via the rotary switch, and the time delay (Δt) can be set to 0 ms, 60 ms, 150 ms, 500 ms, or 1 s. Earth leakage can be disabled entirely by switching IΔn to OFF. The trip unit is electronic, not thermal-magnetic. This matters for motor or transformer feeders where re-acceleration inrush follows a trip.
Standards, approvals, and deployment context
It carries Pollution Degree 3 per IEC 60947-1 — suitable for industrial enclosures where conductive pollution (dust, condensation) is expected.
Sourcing and procurement note
For a BOM line carrying C6334A570, the key fit confirmation is the 570 A rating at 40 °C and the 3P 3D pole configuration. The trip unit is fixed-mount and mates with any ComPacT NSX400...630 frame breaker.