The Schneider Electric C254MG200D is a TM-G thermal-magnetic trip unit for the ComPacT NSX100...250 DC range, rated 200 A at 40 °C and designed for DC networks up to 750 V DC. The trip unit is intended for generator protection applications, meaning its curve and pickup settings are tuned for the inrush and fault characteristics of generator circuits.
The 200 A rating at 40 °C sets the continuous current the trip unit can carry without nuisance tripping — a generator feeder sized for 200 A continuous load is the target. The instantaneous pickup is fixed at 530 A, which is 2.65× In, a typical magnetic threshold for generator protection that avoids tripping on motor starting inrush while clearing hard faults. The long-time pickup (Ir) is adjustable from 0.7 to 1.0× In, giving the commissioning engineer ±30% flexibility to match the actual generator nameplate without swapping the trip unit. Rated operational voltage of 750 V DC covers common 500 VDC and 750 VDC battery banks, solar string combiners, and DC bus systems — the 4-pole series configuration handles the higher DC voltage by splitting the arc across multiple gaps.
Integration notes
The trip unit mounts into a ComPacT NSX250 DC fixed circuit breaker. The 4-pole configuration occupies the full width of the breaker frame.