Siemens 3VL9431-7DC30 MCCB

Independent Thermal-Magnetic Trip Unit (Overcurrent Release) for SENTRON 3VL Series MCCBs

Compatible Circuit Breaker Frame: VL400 frame size (3VL4xxx 400A frame moulded case switches)

Pole Count: 3-pole, LI thermal-magnetic trip for power distribution protection (Overload + Instantaneous Short-circuit)

1. Breakdown of Order Code 3VL9431-7DC30
2. 3VL: Main series of SENTRON moulded case circuit breakers
3. 9: Suffix 9 = Internal Accessory / Independent Trip Unit (Not a complete circuit breaker body)
4. 4: Compatible frame size VL400 (400A frame)
5. 31: Trip current specification code
6. 7: LI thermal-magnetic trip (Distribution protection, non-time-delayed short-circuit)
7. D: Connection type – Screw terminal connection
8. C: Standard version, universal for AC applications
9. 30: 3-pole, no additional auxiliary contacts, standard delivery configuration

III. Core Setting Parameters (Key Protection Values)

1. Electrical & Mechanical Parameters
2. Applicable Voltage

AC: 50/60Hz, max. 690V

DC: max. 440V

2. Mounting Method: Direct replacement and installation onto the base of 3VL4xxx VL400 circuit breakers; no cabinet modification required
3. Net Weight: Approx. 1.42~1.46kg, individually packed per unit
4. Connection Terminals: Screw compression terminals, compatible with copper busbars and cable lugs
5. Standard Certifications: CE, CCC, IEC 60947-2 standard for moulded case circuit breakers
6. Application Scenarios
7. Replacement of trip units for VL400 MCCBs in low-voltage complete switchgear and power cabinets
8. Protection of incoming and outgoing distribution circuits (cables, busbars) in factories and buildings
9. General load protection (Not dedicated for motors; motor loads require motor-specific trip units)
10. Project retrofits: Spare replacement part for failed trip units of existing 3VL400 circuit breakers
11. Examples of Matching Circuit Breaker Bodies

Directly mountable on the following 400A frame circuit breakers:

3VL4731-1DC36-0AA0

3VL4740-1AA36-0AA0

All standard 3-pole VL400 frame moulded case switches in the 3VL4xx range

VII. Differentiation of Equivalent Series Replacements (Selection Pitfall Avoidance)

3VL9431-6DC30: Thermal-magnetic trip for motor protection with different Ii setting range; non-interchangeable

3VL9431-7SP30: Plug-in terminals; screw type D model cannot directly replace plug-in SP model

3VL96xx: Compatible with VL630 frame; larger frame dimension, cannot be fitted to VL400 bodies

VIII. Installation Precautions

1. Disconnect upstream power supply and perform full power cut-off before replacing the trip unit
2. After adjusting the Ir (overload) and Ii (short-circuit) knobs, fasten anti-loosening screws to prevent setting drift during operation
3. Only compatible with 3-pole VL400 circuit breakers; 4-pole VL400 breakers require 4-pole trip units from the 3VL944x series
4. No derating required for long-term operation at ambient temperature ≤50°C; reduce Ir setting current if temperature exceeds 50°C

Full List of Applicable Industries for Siemens 3VL9431-7DC30 (315A LI Thermal-Magnetic Trip Unit for VL400 Distribution Frame)

This model is a distribution-specialized thermal-magnetic trip unit (not for motor use), compatible with 3VL4xxx 400A frame MCCBs, with adjustable Ir=250~315A. It provides overload and instantaneous short-circuit protection for busbars, cables, transformers and general power feeders. It is not suitable for main circuits of high-power three-phase motors (3VL9431-6DC30 shall be selected for motor applications).

1. General Manufacturing Industry (Most Widely Used)
2. Machining & Equipment Manufacturing

Protection for branch feeders and busbar outlets in machine tool plants, automated production lines, stamping/forging workshop MCC (Motor Control Centers) and workshop power distribution cabinets; 315A circuits suit centralized power supply loops for large gantry milling machines and CNC production lines.

2. Complete Vehicle & Auto Component Plants

Low-voltage power cabinets in stamping, welding and coating workshops, general feed switches for workshop zoning, spare trip units for 400A MCCBs in factory substations and retrofit replacements.

3. Rubber & Plastics, Textile, Paper & Printing Industries

Incoming and outgoing circuits of distribution cabinets for extruders, setting machines and paper main drives; protection of factory cable trunk lines, suitable for ordinary dusty industrial environments.

4. Metallurgy, Steel Structure & Metal Processing

Auxiliary power distribution for steel rolling, power circuits in steel cutting workshops, auxiliary power feeders for medium-frequency furnaces; withstand short-circuit protection under impulse loads.

1. Municipal Water, Wastewater & Environmental Protection Industry
2. Sewage Treatment Plants, Water Purification Plants & Pump Stations

Main distribution cabinets in pump houses, busbar feeders for large water pumps, distribution circuits for blowers and sludge dewatering equipment; spare replacement of 400A MCCBs in plant substations.

2. Waste Incineration & Kitchen Waste Treatment Plants

Auxiliary power supply for incinerators, distribution cabinets in leachate treatment workshops, centralized power circuits for fans and air compressors.

3. Municipal Heating & Heat Stations

Low-voltage power distribution in heat exchange stations, trunk line protection for circulating pumps, branch switches of boiler room power cabinets.

III. Construction & Commercial Buildings

1. Large Commercial Complexes, Shopping Malls & Hotels

Zonal main switches in underground power distribution rooms, feeders for central air conditioning main units, power busbar protection for underground parking garages; 315A rating matches power supply circuits for large chillers.

2. Grade-A Office Buildings & Standard Industrial Parks

Floor main distribution cabinets, power incoming feeders for equipment rooms, spare trip units for VL400 breakers in park power houses.

3. Hospitals & Healthcare Facilities

Main medical power distribution, standby power feeders for operating rooms, high-reliability distribution protection to meet continuous power supply requirements for medical loads.

4. Schools, Stadiums & Exhibition Centers

Power distribution cabinets for venues, centralized distribution trunk lines for central air conditioning and stage equipment.

1. Transportation Infrastructure
2. Rail Transit (Metro, High-Speed Railway Stations, Intercity Rail)

Station power distribution rooms, feeders for ventilation and water supply & drainage equipment, low-voltage power distribution in depot maintenance workshops; suitable for maintenance replacement of 400A MCCBs inside stations.

2. Airports, Ports & Logistics Warehousing Parks

Main power distribution for terminal buildings, distribution cabinets for dock handling equipment, trunk line protection for large cold storage warehouses.

3. Tunnels & Highway Service Areas

Power distribution rooms for tunnel fans, main distribution switches for service area comprehensive buildings.

1. New Energy Industry
2. Ground-Mounted PV Power Stations & Commercial & Industrial Distributed PV Systems

Distribution cabinets on the AC side of inverters, low-voltage feeders of step-up stations, power busbar protection in PV plants (supports AC 690V / DC 440V).

2. Wind Farms & Energy Storage Power Stations

Low-voltage outgoing circuits of box transformers, auxiliary power loops of energy storage containers, spare VL400 breakers for station power distribution rooms.

3. Centralized EV Charging Stations

Main distribution cabinets for large charging yards, protection of 315A power supply circuits for multi-charger clusters.

1. Data Centers & Precision Equipment Rooms

Low-voltage power cabinets in IDC rooms, cloud computing centers and server rooms, UPS input & output feeders. Protects server room busbars, precision air conditioners and uninterruptible power loads; accurate overload isolation reduces the risk of full-site power outages.

VII. Chemical, Grain, Oil & Food Processing

1. Fine Chemical & Daily Chemical Plants

Main distribution cabinets outside explosion-proof zones of production workshops, power trunk lines for circulating pumps and agitators (non-explosion-proof body only for non-hazardous zones).

2. Grain, Beverage & Food Processing Plants

Power circuits for filling and fermentation workshops, centralized power busbar protection for cold storage facilities.

VIII. Other Supporting Industries

1. Complete Electrical Equipment Manufacturers (Core OEM Customers)

Original matching spare trip units for low-voltage switchgear, power cabinets and MCC cabinets, mass-fitted to 3VL400 circuit breakers before factory delivery.

2. Industrial & Mining Retrofit, Electromechanical Maintenance Projects

Power distribution renovation of aging factories, spare replacement for damaged trip units of existing VL400 circuit breakers.

3. Cold Chain Warehousing & Cold Storage Industrial Parks

Centralized power supply circuits for large cold storage compressors, main feeder protection for refrigeration equipment rooms.

Industry Selection Restrictions (Unapplicable Scenarios)

1. Main protection circuits for high-power three-phase motors (Instantaneous Ii setting range cannot match motor starting inrush; 3VL9431-6DC30 motor-specialized model must be selected)
2. High-risk flammable and explosive areas of Zone 1 / Zone 2 explosion-proof divisions (Explosion-proof cabinets are required as accessories; the trip unit itself carries no explosion-proof certification)
3. Vessels and offshore platforms (Special trip unit models with marine certification are required; standard 3VL94 series fails marine classification standards)
4. VL630 frame 630A circuit breakers (Only compatible with 400A VL400 frame; frame dimensions are non-interchangeable)