In depth analysis and selection guide for SIEMENS 3AH3 vacuum circuit breaker technology

System side fault: Higher transient recovery voltage (TRV) rise rate.

Higher test voltage level.

The 3AH37/38 series is designed to meet these harsh conditions, with a rated current of up to 8000A (natural cooling) or 12000A (forced cooling), and a short-circuit breaking current of up to 72-90kA.

Revolutionary Architecture: "Phase Isolation" Three Circuit Breaker Solution

For large generators (especially those with a rated current exceeding 10kA), "phase isolated" switchgear is often used, which places the three phases in separate compartments. To this end, Siemens has launched an innovative three circuit breaker solution:

Use three independent 3AH36 generator circuit breaker modules, each controlling one phase.

Each phase module can integrate isolation switches, grounding switches, and starting isolation switches.

By optimizing parallel operation, this scheme can increase the breaking capacity to 100 kA and the rated current to 12500 A, providing a compact and efficient modern solution for replacing old and bulky compressed air generator circuit breakers.

Secondary equipment and highly flexible selection and configuration

The strong flexibility of 3AH3 is largely reflected in its customizable secondary system.

Release combination

Circuit breakers can be equipped with multiple release devices to achieve different protection and control logics:

Closing coil: used for electric closing.

Split release: used to achieve remote automatic or manual disconnection through protective relays.

Undervoltage release: Automatically opens when the control voltage is lower than the set value.

Current transformer driven release: When there is no external auxiliary power source (such as battery), the protection relay obtains energy through CT to drive the disconnection.

Up to 3 release devices can be installed in combination, and users can choose different types of combinations according to their needs.

Auxiliary contacts and interfaces

The standard equipment provides 6 normally open and 6 normally closed auxiliary contacts, which can be upgraded to 12 normally open and 12 normally closed. The secondary interface provides multiple options such as 24 pole terminal blocks, 24 pole plugs, or 64 pole plugs to meet the needs of different wiring habits and automation systems.

Mechanical and electrical interlocking

It can be equipped with mechanical interlocking devices, which cooperate with the switchgear to reliably prevent the circuit breaker from being closed in non permissible states (such as when the handcart is not in place). It also supports electrical interlocking through auxiliary contacts and logical interlocking with devices such as isolation switches.

Detailed selection and ordering guide

Siemens provides a clear 16 digit order number structure to guide users through configuration.

Positions 1-8 (primary part): Define core electrical parameters such as rated voltage, insulation level, rated current, short-circuit breaking current, and inter electrode distance.

Positions 9-16 (secondary section): Define the type of release combination, operating voltage of each coil (optional from 24V DC to 240V AC), operating mechanism type, auxiliary contact configuration, plug type, document language, and power frequency.

Additional options and order codes: For special requirements such as anti condensation heaters, silicone free designs, higher insulation levels, gold-plated contacts, etc., they can be achieved by adding "- Z" and specific order codes after the order number.

The directory provides detailed configuration examples for various voltage levels from 7.2kV to 40.5kV, accompanied by configuration auxiliary brochures and online configuration tool links, making even complex configurations intuitive and convenient.

Technical data, attachments, and full lifecycle support

The latter half of the product catalog provides a complete technical data sheet, including precise dimensions, weight, operating cycle diagrams, and break times for each model.

Accessories and spare parts: A complete list of manual operating handles, lubricants, connector accessories, various coils and motors, spare vacuum arc extinguishing chambers, etc. is provided.

Full lifecycle support: Siemens emphasizes that when ordering spare parts, the equipment model, serial number, and manufacturing year must be provided to ensure a complete match of the spare parts. At the same time, the inquiry form at the end of the catalog provides a standardized template for customers to communicate with Siemens technical support teams.