The Schneider Electric C1647A160 is a MicroLogic 7.2 E AL electronic trip unit for the ComPacT NSX100...250 molded-case circuit breaker range. This is the brain that goes into the breaker frame; you order it separately and snap it into the NSX cradle. The LCD display gives local readout of metered values, protection settings, and event logs without needing a laptop.
The 7.2 E AL sits above the basic thermal-magnetic trip units in the ComPacT family. Where a TM-D relies on a bimetal strip for overload and a solenoid for short-circuit, the MicroLogic 7.2 E AL uses a microprocessor to shape the time-current curve precisely — adjustable long-time pickup from 63 to 160 A, short-time delay from 0 to 0.4 s (I²t on or off), and instantaneous pickup that you set to coordinate downstream. The E AL suffix adds integrated earth-leakage sensing (adjustable IΔn via rotary switch), which a standard MicroLogic 7.2 E does not carry. If your panel requires earth-leakage detection at the breaker without a separate RCD module, this is the variant that saves the DIN rail slot.
Mounts into the ComPacT NSX100...250 fixed or plug-in breaker cradle. The 4P version (C1647A160) occupies all four pole positions with the neutral on the left. Wiring the control power for the electronic trip unit is handled through the breaker's internal connections — no separate auxiliary supply needed. The LCD display and LED indicators (green for ready, red for overload at 105 % Ir, orange for 90 % Ir) are visible through the front cover window. Protection settings are adjusted via the front rotary dials and DIP switches; the thermal memory holds the thermal state for 20 minutes after a trip, so reclosure after a momentary overload does not reset the protection model prematurely.
Rated operational voltage is 440 V AC at 50/60 Hz, pollution degree 3 per IEC 60947-1, IP40 front face. The trip unit communicates metering data — energy, power quality, demand values, time-stamped events — through the breaker's communication port (optional Modbus or wireless module required separately). It also logs earth-leakage current maximeters and minimeters. Neutral protection is selectable: 0.5 × Ir (3D + N/2), 1 × Ir (4D), or no protection (3D).