Siemens medium voltage vacuum switch technology and components

3AH3 high-capacity scenario rated voltage 40.5kV, rated current 4000A, short-circuit breaking current 63kA, spring energy storage mechanism/magnetic operation mechanism

3AH36/37/38 generator circuit rated voltage 24kV, rated current 8000A, short-circuit breaking current 72kA, spring energy storage mechanism

3AH47 traction power supply (1/2 pole) compatible with 16.7Hz/25Hz/50Hz/60Hz, mechanical life of 60000 times, spring energy storage mechanism

Outdoor circuit breaker 3AF0 (tank type) for outdoor distribution, rated voltage for harsh environments of 40.5kV, rated current of 2500A, short-circuit breaking current of 31.5kA, spring energy storage mechanism, compliant with IEC 62271-100 S2 level

SDV (Dead Can) outdoor power distribution, including anti arc rated voltage of 38kV, rated current of 3000A, short-circuit breaking current of 40kA, spring energy storage mechanism/magnetic operation mechanism

(2) Recloser (3AD series)

Function: Integrated switch unit and controller, can automatically detect faults and complete multi segment coincidence, reducing power outage time caused by temporary faults;

Core parameters: rated voltage ≤ 38kV, rated current ≤ 800A, short-circuit breaking current ≤ 16kA, typical coincidence sequence O-0.2s-CO-2s-CO-2s-CO;

Controller: Provides 7SR224 (Reyrolle series) and 7SC80 (SIPROTEC series), supports communication protocols such as IEC 61850 and MODBUS, and is compatible with smart grids.

(3) Vacuum contactor (3TL series)

Function: High frequency switching (≤ 3 million mechanical lifetimes), suitable for loads such as motors, transformers, capacitors, etc;

Core model parameters:

Model Rated voltage Rated current Mechanical life Electrical life (rated current) Suitable load type

3TL81 7.2kV 400A 1 million times 250000 times motor (AC-3/AC-4), transformer

3TL61 7.2kV 450A 3 million times 1 million times motor (AC-3/AC-4), capacitor

3TL65 12kV 400A 1 million times 500000 times motor (AC-3/AC-4), reactor

3TL71 24kV 800A 1 million times 500000 times large capacity motor and transformer

Contactor fuse combination (3TL62/63/66): Integrated high-voltage HRC fuse, short-circuit breaking current ≤ 50kA, suitable for high current scenarios (such as 450A rated current).

(4) Switch - Isolation switch

Arc extinguishing principle: using hard gas to extinguish the arc. When the arc is generated, the insulating material releases gas to quickly extinguish the arc (the gas is non renewable and the number of operations is lower than that of vacuum equipment);

Function: It combines the functions of switching (on/off load current) and isolation (safe isolation distance), with high cost-effectiveness;

Application scenario: Industrial distribution and substation auxiliary circuits require the use of fuses to achieve short-circuit protection.

2. Non switch components

(1) Lightning arrester and voltage limiter

Function: Protect equipment from lightning overvoltage (external) and operation/grounding fault overvoltage (internal) damage;

Core model parameters:

Type, Model, Applicable Scenarios, Rated Voltage (Maximum), Nominal Discharge Current, Shell Material

Voltage limiter 3EF motor, dry-type transformer, frequency converter 12kV 1kA polyethylene

Lightning arrester 3EK4 distribution network, medium voltage switchgear 45kV 10kA (AC) silicone rubber

Line lightning arrester 3EK7 outdoor line protection 72.5kV 10kA silicone rubber

(2) High voltage fuse (3GD series)

Function: Short circuit protection, which melts when the current exceeds the threshold, cuts off the fault current, and protects equipment such as transformers, motors, capacitors, etc;

Classification:

Backup fuse: suitable for 7.2kV-36kV, rated current 6.3A-315A, short-circuit breaking current 40kA-63kA;

Motor protection fuse: suitable for 7.2kV-12kV, rated current 50A-315A, short-circuit breaking current 50kA;

Installation: Supports 1-phase/3-phase installation and can be combined with switchgear (such as switch fuse combination).

(3) Protection and measurement transformers

Current Transformer (CT):

Function: Convert high current proportionally to low current (for measurement/protection equipment use) to achieve electrical isolation;

Key requirements: Cannot operate in an open circuit (to avoid overvoltage), can have multiple secondary windings (measurement/protection separated);

Types: Indoor support type, indoor sleeve type, outdoor type.

Voltage Transformer (VT):

Function: Convert high voltage proportionally to low voltage (for measurement/protection equipment use);

Key requirements: Do not short-circuit operation (to avoid overheating), some windings with residual voltage (ground fault detection);

Type: Indoor, Outdoor.

(4) Auxiliary switch (3SV9 series)

Function: Auxiliary contacts for mechanical operation, used for electrical interlocking, auxiliary contactor/coil control, and motor operating mechanism drive;

Key parameters: rated voltage 230V AC/240V DC, rated thermal current 10A, mechanical life 100000 times, electrical life 30000 times;

Configuration flexibility: Switching levels 2-26, contacts can be customized as normally closed (NC), normally open (NO), or switch contacts, supporting different switching angles and overlapping contacts.