Circuit breaker S 311 1P B 25A 10000A TX3 404086

Single-phase circuit protection in residential and commercial installations

The S 311 miniature circuit breaker from the TX³ series is a single-pole device designed to protect against the effects of short circuits and overloads in single-phase circuits. It features a rated short-circuit capacity of 10 kA according to EN 60898-1 and 16 kA according to IEC 60947-2, making it suitable for both standard residential installations and commercial facilities with higher requirements.

A rated current of 25 A combined with B characteristic means that the electromagnetic trip will act at loads exceeding 3-5 times the rated value. This feature makes the circuit breaker perform well in circuits with small electric motors and devices with low inrush currents—where higher characteristics (C or D) might react too slowly or cause unnecessary tripping.

The width of one module on a TH35 rail allows for compact mounting in distribution boards where available space is limited. The design with bottom terminals and covers simplifies wiring—wires are introduced seamlessly, and the risk of accidental contact with live parts is minimized.

Operating parameters and environmental conditions

The device operates on a 230/400 V AC network at a frequency of 50-60 Hz. The maximum operating voltage reaches 440 V AC, providing a safety margin in typical installation conditions. An insulation voltage of 500 V and an impulse withstand voltage of 4 kV confirm the device's resistance to surges occurring in building installations.

The IP20 protection rating means the circuit breaker is protected against finger contact and access to live parts, but it is not intended for damp rooms—where enclosures with a higher IP class should be used.

A mechanical durability of 20,000 operations and electrical durability of 10,000 operations attest to the robustness of the construction and readiness for many years of operation. Energy limiting class 3 indicates effective attenuation of short-circuit energy—the trip mechanism quickly interrupts the electric arc, protecting both the device itself and other elements of the installation.

Compatibility and expansion

TX³ series circuit breakers work with a wide range of auxiliary accessories—auxiliary and signaling contacts, undervoltage and shunt trips, as well as remote switching actuators. This allows for the construction of advanced systems for device status signaling or automatic distribution board control.

The connection of conductors with cross-sections from 1 to 25 mm² enables the use of both thinner control wires and thicker power cables without the need for adapters. The circuit breaker is mounted on a standard TH35 rail—the same way as most modular devices available on the market.

The black switching lever ensures a clear device status even in poorly lit distribution boards. The gray housing (RAL 7035) maintains visual consistency with other elements of the TX³ series.

The circuit breaker complies with IEC/EN 60898-1 and IEC/EN 60947-2 standards—it can be used as standalone protection or work in conjunction with separately mounted residual current devices (the circuit breaker itself does not support RCD connection).