Siemens Circuit breaker for transformer protection, size S0, 18-25A Part number 3RV2421-4DA20

Product Overview

The Siemens 3RV2421-4DA20 is a SIRIUS size S0 circuit breaker designed for transformer protection. It offers an adjustable overload (A-Release) range of 18 … 25 A, features a fixed instantaneous short-circuit (N-Release) rating of 400 A, and is equipped with spring-type terminals for reliable conductors connection. Its compact size S0 makes it suited for small switchgear and distribution systems requiring high switching capacity.

Key Features

• Size S0 circuit breaker from the Siemens SIRIUS 3RV2 series
• Transformer protection version with adjustable overload range of 18 … 25 A
• Fixed short-circuit trip (instantaneous) rated at 400 A (N-Release)
• Spring-type terminals for secure connection and vibration resistance
• Standard switching capacity for switchgear applications with high loads
• Compact 3-pole construction suitable for DIN-rail or panel mounting

Technical Specifications

• Product Series: SIRIUS 3RV2
• Article Number: 3RV2421-4DA20
• Size Designation: S0
• Adjustable Overload Range (A-Release): 18 … 25 A
• Fixed Short-Circuit Release (N-Release): 400 A
• Breaking Capacity (Icu) at 400 V AC: 55 kA
• Main Rated Operational Current (AC-3) at 400 V: 25 A
• Operating Voltage (Ue) Range: 20 … 690 V AC
• Number of Poles: 3 P
• Terminal Connection Type: Spring-type terminals for main circuit
• Ambient Operating Temperature: –20 °C … +60 °C
• Installation Depth / Width: Height ~119 mm, Width ~45 mm, Depth ~97 mm

Compliance & Certifications

• Manufactured by Siemens in accordance with SIRIUS series motor-protection and switching devices
• Complies with IEC/EN 60947 series for circuit-breakers and automatic disconnect devices
• Designed for use in transformer protection and industrial switchgear systems

Applications

Ideal for transformer protection and heavy duty switchgear applications where a compact size S0 circuit breaker is required with a high instantaneous trip capability. Typical use cases include protection of transformer feeders, motor distribution boards, and industrial power panels requiring reliable overload and short-circuit protection with minimal footprint.