What this trip unit does and why it matters
The Schneider Electric C1647E160 is a MicroLogic 7.2 E electronic trip unit from the ComPacT NSX100...250 range, rated 160 A at 40 °C for 4-pole distribution applications on AC networks at 50/60 Hz. It provides LSIR protection — long-time (L), short-time (S), instantaneous (I), and earth-leakage (R) — all adjustable, with an integrated earth-leakage Class A sensor. The LCD display and local signalling LEDs (green ready, red overload at 105% Ir, orange overload at 90% Ir) give you real-time status without opening the panel. The 20-minute thermal memory before and after tripping means the trip curve accounts for prior heating, so nuisance trips on reclose are less likely on a warm cable.
The long-time pickup Ir is adjustable from 63 to 160 A, so you can dial it down to match a downstream load without swapping the trip unit. Instantaneous pickup Ii is also adjustable. Earth-leakage protection can be switched off via the IΔn rotary switch, handy if you're feeding a transformer or a circuit with high natural leakage. Neutral protection offers four settings: 0.5 x Ir (3D + N/2), 1 x Ir (4D), 1.6 x Ir (3D + OSN), or no protection (3D).
The trip unit mounts fixed in the ComPacT NSX250 circuit breaker — no separate DIN-rail bracket required. The IP40 front face (IEC 60529) is fine for enclosed panels; if the panel door is open for commissioning, keep debris out. Communication data includes maximeters, minimeters, power quality, earth-leakage current, protection and alarm settings, instantaneous and demand values, energy metering, time-stamped histories, event tables, demand current and power, test reports, and maintenance indicators — all accessible via the LCD display or the communication port on the breaker. No zone selective interlocking (ZSI) on this variant, so coordination relies on time-current curves.