For a 0.5 kW ventilation fan or a small compressor, a standard B curve breaker might trip every time the motor starts. The ABB S201-K10 solves this problem by raising the magnetic trip threshold to 80 A (8 times the 10 A rated current), giving the motor enough room for its brief inrush while still responding quickly to a genuine short circuit.

What Loads Work with a 10 A K Curve
This rating is suitable for small motors up to about 1 kW, refrigeration compressors in compact appliances, small water pumps, ventilation fans, solenoid valves, control transformers for PLCs and contactors, and some lighting circuits where electronic ballasts or LED drivers produce high inrush currents. The K curve sits between B (3–5×In) and C (5–10×In), with a defined 8×In magnetic threshold that aligns with motor protection standards.

Electrical and Mechanical Specifications
The S201-K10 is a 1‑pole device occupying 17.5 mm width on a 35 mm DIN rail. It is rated for 230/400 V AC and 72 V DC, with a breaking capacity of 6 kA (Icn per IEC/EN 60898-1). The thermal overload follows the K curve characteristic; the electromagnetic trip operates at 80–100 A. Terminals accept solid conductors up to 25 mm² or stranded up to 16 mm², with a recommended torque of 2.8 N·m. Operating temperature range is –25 °C to +55 °C. Mechanical and electrical endurance are both rated at 20,000 cycles. The red‑green contact position indicator gives clear visual feedback of the switching state.

Why the K Curve Matters for Motors
A small motor’s locked‑rotor current can reach 6–10 times its full‑load current. If that peak exceeds a B curve’s magnetic threshold (30–50 A for a 10 A device), the breaker trips — not because of a fault, but because it is doing exactly what it was designed to do. The K curve simply moves the threshold higher, accepting the inrush while preserving rapid short‑circuit response. For motor control circuits defined under DIN VDE 0660, the K characteristic is the recommended choice.

Installation and Coordination
Mounts directly onto 35 mm DIN rail per EN 60715. Supply can be from top or bottom. The device can be sealed in both ON and OFF positions for tamper‑resistant installations. For remote indication, the S201‑K10 accepts auxiliary contacts (S2C‑S/H6R) and shunt trips. The S200 series also supports bottom‑fitting auxiliary contacts that save 50 % of panel space compared to side‑mounted alternatives.

Compliance and Origin
Manufactured in Germany, the S201‑K10 meets IEC/EN 60898-1 (household installations) and IEC/EN 60947-2 (industrial applications). UL 1077 recognition is available for North American control panels. The device is RoHS compliant and SVHC‑free under REACH. EAN: 4016779496117.

A Practical Sizing Note
The 10 A rating assumes the downstream cable is sized appropriately (typically 1.5 mm² copper, depending on installation method). Do not use a 10 A breaker on a circuit wired with 0.75 mm² cable — that is a fire risk. For pure resistive loads with no inrush, a B curve would be the better choice; for moderate inrush from lighting or small transformers, C may suffice. But for small motors and control transformers, the K curve is often exactly what the circuit needs.