The S203-K40 is a 3-pole miniature circuit breaker rated 40 A with a Trip Curve K characteristic, meaning it trips magnetically at 8–12x rated current — designed for loads with moderate inrush like motors, transformers, and solenoid valves where a standard Curve C might nuisance-trip on startup but Curve D would be too slow for conductor protection. Rated 277 VAC phase-to-neutral. Interrupting capacity of 10 kA at 277 VAC. Mounts on standard DIN rail.
S203-K40 Miniature Circuit Breaker, 3P, 40A, Curve K, DIN Ra
MPNS203-K40
S203-K40, 3-pole miniature circuit breaker, 40 A, Trip Curve K, 277 VAC, 10 kA interrupting capacity, DIN rail mount.
$25.40Ref. price · indicative, final on quote
Source DocumentedChannel stated on listing & quote
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Independent China distributor & sourcing agent· Listing updated Sep 2026
Specifications
| Parameter | Value |
|---|---|
| Amps | 40 |
| Type | Trip Curve K |
| Poles | 3 |
| Mounting | DIN Rail |
| Volts AC | 277 |
| Breaking capacity | 10 kA |
Product details
Frequently asked questions
Will S203-K40 drop into a panel that was specified around S203-D13 without rewiring?
Physically yes — both mount on the same DIN rail and share the same 3-pole footprint. But the K40 is 40 A vs 10 A, so the downstream conductor and load must be rated for 40 A. The trip curve is also different (K vs D), so coordination with upstream devices may change.
MPN
S203-K40