As Nordic distributors of advanced electrical interconnect solutions, we examine DEGSON Technology's bolt connection approach to high-current terminal blocks, focusing on the fundamental engineering principles that govern thermal management and current density optimization in industrial power distribution systems.
Introduction: High-Current Terminal Block Challenges
Modern industrial power distribution systems require terminal blocks capable of reliably handling increasing current levels within constrained panel spaces. The fundamental relationship governing all electrical connections is the power dissipation equation:
P = I²R
Where power dissipation increases quadratically with current, making contact resistance minimization and thermal management the primary design challenges. Even small improvements in contact resistance yield significant benefits at high current levels.
DEGSON Technology Co., Ltd. addresses these challenges through bolt connection technology that provides multiple parallel current paths and enhanced contact force distribution compared to conventional single-screw terminals.
Terminal Block Design Comparison
Conventional Screw Terminal
Single-Point Connection
DEGSON Bolt Connection
Multi-Point Connection
Distributed contact stress
Engineering Principles
Current Distribution
Multiple parallel paths can distribute current load, potentially reducing individual path stress and improving overall reliability.
Contact Force
Higher bolt torque specifications typically provide increased contact force, which can improve electrical contact quality.
Space Utilization
Multi-wire capability may reduce the number of terminal positions required for complex wiring applications.
Heat Distribution
Distributed connection points can help spread heat generation across a larger contact area compared to single-point connections.
Figure 1: Static comparison showing single-point vs multi-point connection architecture. The graph shows how bolt connections provide multiple current paths and distributed contact points compared to conventional single-screw designs.
DEGSON Bolt Series Portfolio:
According to DEGSON's technical catalog, the Bolt series encompasses three primary configurations targeting different current ranges and applications:
Bolt6 Series: Current rating up to 1000V/125A (IEC) / 600V/115A (UL), accommodating 2.5-35mm² conductors
Bolt8 Series: Current rating up to 1000V/192A (IEC) / 600V/175A (UL), accommodating 2.5-70mm² conductors
Bolt10 Series: Current rating up to 1000V/309A (IEC) / 600V/310A (UL), accommodating 6-150mm² conductors
For specialized energy storage applications, DEGSON offers 600A variants meeting UL4128 and TÜV standards with IP67 environmental protection.
The bolt connection mechanism enables multiple wire terminations within a single terminal position, potentially improving space utilization compared to conventional single-wire terminals.
BS6
Medium Current Applications
Current Rating (IEC):125A @ 1000V
Current Rating (UL):115A @ 600V
Wire Range:2.5-35mm²
AWG Range:16-12AWG
Temperature Range:-40°C to +105°C
Applications:
Industrial Control
Motor Drives
Power Distribution
BS8
High Current Power Systems
Current Rating (IEC):192A @ 1000V
Current Rating (UL):175A @ 600V
Wire Range:2.5-70mm²
AWG Range:16-2/0AWG
Temperature Range:-40°C to +105°C
Applications:
Heavy Industry
Large Motors
Power Feeders
Switchgear
BS10
Ultra-High Current Applications
Current Rating (IEC):309A @ 1000V
Current Rating (UL):310A @ 600V
Wire Range:6-150mm²
AWG Range:10-350AWG
Temperature Range:-40°C to +120°C
Applications:
Energy Storage
EV Charging
Battery Systems
600A Variants Available
| Specification |
BS6 Series |
BS8 Series |
BS10 Series |
| Maximum Current (IEC) | 125A @ 1000V | 192A @ 1000V | 309A @ 1000V |
| Maximum Current (UL) | 115A @ 600V | 175A @ 600V | 310A @ 600V |
| Wire Range (Metric) | 2.5-35mm² | 2.5-70mm² | 6-150mm² |
| Wire Range (AWG) | 16-12AWG | 16-2/0AWG | 10-350AWG |
| Connection Type | Bolt Connection | Bolt Connection | Bolt Connection |
| Operating Temperature | -40°C to +105°C | -40°C to +105°C | -40°C to +120°C |
| Material Rating | PA66 UL94 V0 | PA66 UL94 V0 | PA66 UL94 V0 |
| Protection Rating | IP20 (Standard) | IP20 (Standard) | IP67 (Special Variants) |
| Standards Compliance | IEC 60947-7-1, UL 1059 | IEC 60947-7-1, UL 1059 | IEC 60947-7-1, UL 1059, UL4128 |
| Special Features | Multi-wire capability | Enhanced current capacity | 600A energy storage variants |
Important Notes:
All specifications are based on DEGSON's technical documentation. Actual performance may vary based on installation conditions, ambient temperature, conductor type, and connection quality. Always consult current product datasheets and follow manufacturer installation guidelines for specific applications.
Figure 2 Location: Comprehensive specifications table displaying Bolt6/Bolt8/Bolt10 current ratings, wire ranges, temperature limits, and applications.
Contact Resistance and Current Distribution Principles
The effectiveness of any high-current terminal depends on minimizing contact resistance. While specific contact resistance values vary based on installation conditions, bolt torque, and environmental factors, the principle of parallel current paths offers theoretical advantages.
For a terminal with n parallel current paths carrying equal current:
• Current per path: I_path = I_total/n
• Power per path: P_path = (I_total/n)² × R_contact
• Total power: P_total = I_total² × R_contact/n
This demonstrates that distributing current across multiple parallel paths reduces total power dissipation proportional to the number of paths, assuming equal contact resistances.
Contact Force Considerations: Higher bolt-applied contact forces generally improve electrical performance by:
• Increasing real contact area
• Reducing constriction resistance
• Improving resistance to vibration-induced loosening
Figure 3: The chart illustrates how small changes in contact resistance significantly impact power dissipation at high currents.
Thermal Management Fundamentals
Terminal block temperature rise depends on power dissipation and thermal resistance to ambient conditions:
ΔT = P × R_th
Where thermal resistance (R_th) varies significantly based on:
• Terminal block size and materials
• Mounting orientation and panel configuration
• Air circulation and ambient conditions
• Conductor heat sinking effects
Critical Design Principle: One always need to verify actual temperature rise through measurement or thermal modeling for specific installation conditions. Manufacturer ratings provide starting points, but real-world thermal performance requires validation.
Thermal Management Strategies:
1. Minimize power dissipation through low contact resistance
2. Enhance heat dissipation through conductor heat sinking
3. Ensure adequate ventilation around terminals
4. Consider derating for elevated ambient temperatures
Fundamental Thermal Relationship
ΔT = P × Rth
Temperature Rise = Power Dissipation × Thermal Resistance
Thermal resistance depends on installation conditions—measure, don’t assume.
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Heat Generation
Heat is generated by I²R losses at contact interfaces. Even small contact resistances can create significant heating at high currents.
🌡️
Heat Transfer
Heat flows via conduction (terminal body), convection (air), and conductor heat sinking. Multiple paths improve performance.
📐
Contact Area
Larger real contact area lowers current density and spreads heat generation over a broader surface.
⚖️
Force Distribution
Correct clamping force improves electrical/thermal contact; distributed loading reduces hot spots.
Factors Affecting Thermal Performance
🏗️
Terminal Size
Affects heat capacity and cooling area.
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Air Circulation
Ventilation and orientation drive convection.
🌡️
Ambient Temperature
Higher ambient reduces margin.
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Conductor Heat Sinking
Wires conduct heat away.
📦
Enclosure Design
Materials & spacing set the thermal environment.
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Installation Quality
Proper torque and prep minimize contact resistance.
Temperature Verification Process
1
Design Calculation
Estimate power from expected contact resistance & current.
2
Installation
Follow torque specs and conductor prep.
3
Load Testing
Apply rated current until steady state.
4
Measure
Use IR camera or probes at connection points.
⚠️
Critical Warning
Do not assume Rth values. Verify temperature rise on the actual installation before sign-off.
Thermal Management Best Practices
✓Size conductors per code before selecting terminals.
✓Choose terminals with margin above operating current.
✓Follow torque specs precisely.
✓Keep spacing for airflow and heat dissipation.
✓Measure temperature rise or run thermal analysis.
✓Plan periodic inspections & re-torque where applicable.
Figure 4: The graph exhibits the fundamental ΔT = P × R_th relationship while includes measurement verification process and pointing out to the importance of the thermal resistance measurement and testing processes for safe and optimal performance.
Application Engineering: Selection Guidelines
Electric Vehicle Charging Infrastructure
DC fast charging applications typically require 150-350kW power transfer at 400-800V, resulting in current levels of 200-500A. Terminal selection must consider:
• Conductor sizing per applicable electrical codes
• Terminal current rating with appropriate safety margins
• Environmental protection (often IP67 for outdoor installations)
• Thermal performance verification under actual operating conditions
DEGSON's Bolt10 series with 309A continuous rating and available 600A variants provides options for high-power charging applications.
Energy Storage Systems
Battery management systems require reliable high-current connections for charge/discharge cycles. Critical considerations include:
• Long-term reliability (typically 20+ year design life)
• Thermal cycling resistance
• Environmental protection within battery enclosures
• Compliance with energy storage standards (UL4128, TÜV)
Industrial Motor Control
Three-phase motor applications present unique challenges:
• High inrush currents (typically 6x rated current)
• Vibration resistance requirements
• Space optimization for multiple phases
• Maintenance accessibility
Figure 5: The chart demonstrates parallel circuit, showing how current divides across multiple paths (I_path = I_total/n) and how this reduces per-path power dissipation.
Standards Compliance and Certification
DEGSON terminals comply with multiple international standards:
Electrical Standards:
• IEC 60947-7-1: Terminal blocks for copper conductors
• UL 1059: Terminal blocks
• CSA C22.2 No.158: Terminal blocks
Quality Systems:
• ISO 9001: Quality management
• ISO 14001: Environmental management
• IATF 16949: Automotive quality
• ISO/TS 22163: Railway applications (IRIS)
Application-Specific Standards:
• UL4128: Energy storage systems
• TÜV certification for specialized applications
These certifications provide assurance of design verification and manufacturing quality control.
Installation and Maintenance Considerations
Proper Installation Practices:
1. Follow manufacturer's torque specifications for bolt connections
2. Ensure proper conductor preparation (stripping length, end treatment)
3. Verify adequate clearances for heat dissipation
4. Use appropriate conductor sizing per electrical codes
Maintenance Requirements:
• Periodic torque verification (schedule per manufacturer recommendations)
• Visual inspection for signs of overheating or corrosion
• Thermal imaging surveys for high-current installations
• Connection resistance testing where practical
Vibration Environments: Bolt connections generally provide superior vibration resistance compared to screw terminals due to higher clamping forces and distributed contact areas.
Environmental Performance
DEGSON Bolt series terminals operate across temperature ranges from -40°C to +105°C (standard) or +120°C (specialized variants). Material specifications include:
• Housing: PA66 polyamide with UL94 V0 flame rating
• Contacts: Tin-plated copper alloy for corrosion resistance
• Hardware: Corrosion-resistant steel components
For outdoor or harsh environments, specialized variants offer IP67 protection ratings.
Engineering Selection Process
1
Size Conductors
Apply electrical codes (IEC, NEC, etc.) to determine minimum conductor size based on current, voltage, and installation method.
2
Select Terminal Rating
Choose terminal with current rating ≥ conductor ampacity, considering derating factors and safety margins.
3
Verify Environment
Confirm terminal materials and protection ratings meet environmental requirements (temperature, humidity, vibration).
4
Check Standards
Ensure compliance with applicable standards (IEC 60947‑7‑1, UL 1059, application‑specific requirements).
5
Validate Thermal
Verify temperature rise through measurement or analysis under actual operating conditions.
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EV Charging Infrastructure
Typical Requirements
DC Current Range:200–500A
Voltage Levels:400–800V DC
Power Levels:150–350kW
Temperature Range:‑40°C to +50°C
Critical Considerations
• IP67 protection for outdoor installations
• High frequency charge/discharge cycles
• Rapid temperature changes
• Safety disconnection requirements
DEGSON Solution
Bolt10 series (309A standard, 600A variants) with IP67 protection and enhanced temperature range.
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Energy Storage Systems
Typical Requirements
DC Current Range:300–600A
Voltage Levels:400–1000V DC
Conductor Size:70–150mm²
Service Life:20+ years
Critical Considerations
• Long‑term reliability requirements
• Thermal cycling from charge/discharge
• Battery enclosure environment
• UL4128 and TÜV compliance
DEGSON Solution
Bolt10 600A energy storage variants with UL4128/TÜV certification and proven long‑term reliability.
⚙️
Industrial Motor Control
Typical Requirements
AC Current Range:50–300A
Voltage Levels:380–690V AC
Inrush Current:6× rated current
Phase Configuration:3‑phase + neutral/ground
Critical Considerations
• High vibration industrial environment
• Space optimization for multiple phases
• Maintenance accessibility
• Starting current capability
DEGSON Solution
Bolt8 series (192A) with multi‑wire capability for efficient three‑phase connections and superior vibration resistance.
☀️
Solar Photovoltaic
Typical Requirements
DC Current Range:15–200A
Voltage Levels:600–1500V DC
Service Life:25+ years outdoor
Temperature Range:‑40°C to +90°C
Critical Considerations
• UV radiation exposure
• Temperature cycling
• Moisture and contamination
• Long‑term material stability
DEGSON Solution
Specialized DR271V/DR271R series with UV‑resistant materials and enhanced environmental protection.
Bolt Series Application Suitability Matrix
| Application |
Current Range |
Bolt6 Series |
Bolt8 Series |
Bolt10 Series |
Key Selection Factors |
| Industrial Control |
25–125A |
High |
Medium |
Oversized |
Standard applications, cost optimization |
| Motor Drives |
50–200A |
Limited |
High |
Premium |
Inrush current capability, vibration |
| EV Charging |
200–500A |
Inadequate |
Limited |
Optimal |
High current, environmental protection |
| Energy Storage |
300–600A |
Inadequate |
Inadequate |
Required |
Ultra‑high current, special variants |
| Solar PV |
15–50A |
Suitable* |
Oversized |
Oversized |
UV resistance, long‑term reliability |
* Solar PV applications typically use specialized DR271V/DR271R series rather than Bolt series.
Relevant Standards and Certifications
Electrical Standards
IEC 60947‑7‑1Terminal blocks for copper conductors
UL 1059Terminal blocks (North America)
CSA C22.2 No.158Terminal blocks (Canada)
Application Standards
UL4128Energy storage systems
ISO/TS 22163Railway applications (IRIS)
IATF 16949Automotive quality systems
Quality Systems
ISO 9001Quality management systems
ISO 14001Environmental management
UL94 V0Flammability rating
Figure 6: The chart provides structured selection process and application-specific requirements for EV charging, energy storage, motor control, and solar PV. This includes standards compliance information and suitability matrix for different Bolt series variants.
Economic Considerations
Terminal block selection involves multiple cost factors:
Initial Costs:
• Purchase price differential between technologies
• Installation labor (simplified by multi-wire capability)
• Panel space requirements
Operating Costs:
• Energy losses from contact resistance (verify with actual measurements)
• Maintenance requirements and accessibility
• Reliability and replacement costs
Lifecycle Considerations:
• Expected service life (typically 20+ years for industrial applications)
• Compatibility with future system modifications
• Availability of replacement parts and technical support
Technical Support and Engineering Services
At SAGA Components, we provide local inventory management, competitive pricing, and reliable delivery of DEGSON terminal blocks across the Nordic region. Our team maintains direct relationships with DEGSON's factory to ensure product availability, coordinate special orders, and facilitate technical inquiries when needed. We handle logistics, documentation, and regulatory compliance for Nordic markets, while connecting customers directly with DEGSON's engineering team for specialized technical support beyond standard product selection.
Conclusion
DEGSON's Bolt series bolt connection terminals offer a technically sound approach to high-current applications through multiple parallel current paths and enhanced contact force distribution. While specific performance advantages depend on installation conditions and application requirements, the fundamental principles of reduced contact resistance and improved thermal management provide clear engineering benefits.
For Nordic engineers specifying high-current terminal solutions, DEGSON's comprehensive certification portfolio (ISO 9001, IATF 16949, ISO/TS 22163, UL4128) and proven manufacturing capabilities support reliable performance in demanding industrial, transportation, and energy applications.
The key to successful implementation lies in proper application engineering: size conductors per applicable codes, select terminals with appropriate current ratings and safety margins, and verify thermal performance through measurement or analysis for specific installation conditions.
Technical Support & Product Consultation
Contact Information:
• Email: contact@sagacomponents.com
• Phone: +46 (0) 8 564 708 00
• Web: https://www.degson.com/product/productlist20_4978985.html?lang=en
Contact our technical team today to discuss your power distribution challenges and discover how DEGSON's terminal block solutions can improve your system performance, reduce operational costs, and enhance long-term reliability.
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References
[1] Holm, Ragnar. Electric contacts: theory and application. Springer Science & Business Media, 2013.
[2] Slade, Paul G., ed. Electrical contacts: principles and applications. CRC press, 2017.
[3] IEC 60947-7-1:2009, "Low-voltage switchgear and controlgear - Part 7-1: Ancillary equipment - Terminal blocks for copper conductors." IEC Publications, Geneva.
[4] Bejan, Adrian, and Allan D. Kraus, eds. Heat transfer handbook. Vol. 1. John Wiley & Sons, 2003.
[5] DEGSON Technology Co., Ltd. (2024). DIN Rail Terminal Blocks Technical Catalog - Bolt Series High-Current Bolt Connection Terminals. DEGSON Electronics, Ningbo, China.
