Skip to main content
ABB S203-Z20 — Miniature Circuit Breakers (MCB)

ABB S203-Z20 MCB, 3P, 20A, Curve Z, 10 kA

MPNS203-Z20

ABB S203-Z20, 3-pole miniature circuit breaker, 20 A, Trip Curve Z, 277 V AC, 10 kA interrupting capacity, DIN rail mount.

Source DocumentedChannel stated on listing & quote
Condition PhotosReal unit photos / video on request
WhatsApp AnswersFast human replies for machine-down parts
Worldwide DispatchDHL/FedEx — transit quoted per order
Independent China distributor & sourcing agent· Listing updated Sep 2026

Specifications

S203-Z20 — Specifications
ParameterValue
Amps20
TypeTrip Curve Z
Poles3
MountingDIN Rail
Volts AC277
Breaking capacity10 kA

Product details

Rated current and trip characteristic

This makes it the right choice for protecting semiconductor circuits, control transformers, or sensitive electronic loads where a standard MCB might nuisance-trip on inrush.

Interrupting capacity and voltage rating

Rated at 10 kA interrupting capacity at 277 V AC per pole. The 277 V AC rating covers line-to-neutral on a 480Y/277 V wye system, which is the common commercial lighting and small-power distribution voltage in North America.

The 3-pole housing occupies three modular units (17.5 mm per pole) — 52.5 mm of rail space. No mounting screws needed; clip it on, torque the line and load terminals to the recommended value (typically 2.5 N·m for the cage clamp), and it's locked in. Leave a finger's width of air gap between adjacent breakers if you're running near the 20 A continuous rating — thermal derating in a tightly packed row can reduce the effective trip point.

Frequently asked questions

What is the interrupting rating of the S203-Z20?

10 kA at 277 V AC. That's the maximum fault current the breaker can safely interrupt under short-circuit conditions. Verify that your available fault current at the panel does not exceed this value.

Where can I buy the S203-Z20?

Sourced and quoted to order against an RFQ through independent distribution. Availability and current pricing are confirmed at quote time.

What does Trip Curve Z mean for this breaker?

The Z curve has a magnetic trip threshold of 2 to 3 times the rated current (40–60 A for this 20 A breaker). It's designed for semiconductor protection and sensitive electronic loads where a B or C curve would nuisance-trip on small inrush or transient currents.

MPN
S203-Z20