Application of Low Voltage Insulators in Energy Storage

Introduction

Energy storage systems (ESS) are growing fast. They are essential for renewable energy, grid stability, and backup power. Inside these systems, safety and reliability are top priorities. One key component is the low voltage insulator.

Low voltage insulators separate live conductors from grounded metal parts. They prevent short circuits and protect people from electric shock. In battery storage systems, they work under voltages up to 1,000 V AC or 1,500 V DC.

In energy storage, the wrong insulator choice can lead to arc faults, equipment damage, or even fires. That is why designers follow strict standards such as IEC 60660, IEC 60865, UL 94, GB/T 11022 to ensure safety. This blog explains what low voltage insulators are, their types, why they are needed, and how to select the right one for energy storage applications.

What Are Low Voltage Insulators?

A low voltage insulator is a device that supports and separates electrical conductors at voltages of 1,000 V AC or less (or up to 1,500 V DC). Its role is both electrical and mechanical. It must:

• Provide dielectric strength to prevent breakdown.

• Offer mechanical stability to hold busbars or cables in place.

• Resist environmental conditions such as moisture, dust, or salt mist.

Key performance parameters:

• Dielectric strength: Withstand 2.5 kV AC for 1 minute without flashover.

• Creepage distance: Minimum values based on working voltage (e.g., ≥16 mm/kV DC for UL 1973).

• Comparative Tracking Index (CTI): Often ≥300 for good surface resistance (per IEC 60112).

• Temperature resistance: Suitable for the ESS environment (typically -40°C to +120°C).

Typical applications in ESS:

• Battery rack busbar separation.

• DC combiner box insulation.

• Busbar support in power conversion systems (PCS).

The Type of Low Voltage Insulators

Stand-off Insulators

Low voltage standoff insulators are widely used in ESS. They are shaped like a column and have threaded inserts on each end.
Features:

• Size range: M6 to M12 threads, heights from 20 mm to 100 mm.

• Materials: Epoxy resin, SMC/DMC compounds, or reinforced PA66.

• Benefits: Easy installation, compact size, strong mechanical strength.

• Typical application: Mounting busbars in DC distribution panels inside energy storage cabinets.

For a more detailed explanation of their structure, performance, and installation best practices, you can read our full guide: Busbar Standoff Insulators – Everything You Need to Know.

Busbar Support Insulators

Busbar insulators are designed to hold copper or aluminum busbars in place. They can be fixed by clips, dovetail slots, or bolts.
Advantages:

• Allow slight thermal expansion (±2 mm) to prevent stress on conductors.

• Support heavy loads with high Cantilever Strength and Bending Strength.

• Common in busbar support insulator in battery storage systems.

If you want to explore design types, material options, and testing standards in depth, check out our comprehensive post: Busbar Insulator – A Complete Guide.

SMC/DMC Insulators

SMC (Sheet Molding Compound) and DMC (Dough Molding Compound) are high-strength thermosetting materials. They are widely used because they:

• Provide high CTI (400–600).

• Meet UL 94 V-0 flame resistance.

• Operate at high temperatures (up to 150°C).
  SMC/DMC insulators are ideal for outdoor ESS or high-temperature environments.

Shackle / Spool Insulators

Shackle or spool types are smaller and often used for:

• Cable terminations inside storage systems.

• Mechanical support for smaller conductors.
  They are often made from porcelain, glass, or epoxy resin. They meet mechanical strength classes from GB/T 772 for low voltage applications.

Why Energy Storage Equipment Requires Low Voltage Insulators?

Safety Assurance

In ESS, the risk of electric shock or arc flash is real. Low voltage insulators ensure conductors are safely separated from metal frames. They help meet IEC 62933-5-2 safety requirements.

Short Circuit Prevention

By maintaining proper creepage and clearance distances, insulators stop conductors from touching during faults or vibration. This prevents short circuits that could damage the battery system.

Mechanical Stability

During transport, installation, or seismic events, ESS components experience vibration and shock. Insulators with high bending and cantilever strength keep busbars firmly in place.

Modular Design

Many ESS designs use prefabricated modules. Low voltage standoff insulators and busbar supports allow easy assembly and replacement, reducing downtime.

Environmental Resistance

ESS may operate in high humidity, salt mist, or dusty locations. Materials like SMC/DMC insulators resist tracking, UV, and corrosion, making them reliable in harsh environments.

Design and Material Selection of Low Voltage Insulators in Energy Storage Equipment

Mechanical Design

Steps for designing insulator support:

1. Voltage rating: Determine maximum DC voltage (Vmax) and calculate creepage distance.

2. Mechanical load: Calculate short-circuit forces using:
   F = 2 × 10^-7 × (I² / a) × l,
   where I is short-circuit current, a is spacing, and l is length.

3. Thermal expansion: Consider busbar expansion at high currents and temperatures.

Insulation Performance

Good insulation performance depends on:

• High dielectric strength (≥2.5 kV AC for 1 min).

• Adequate creepage distance per voltage level.

• CTI values suitable for the environment (higher CTI = better tracking resistance).

Material Selection

Common materials:

• Epoxy resin insulators: Good strength, moderate CTI, indoor use.

• SMC/DMC: High CTI, excellent fire resistance, outdoor-capable.

• Ceramic: Excellent heat resistance, brittle, heavier.

Energy Storage Devices: SMC vs. Ceramic Insulators

When choosing between SMC/DMC and ceramic for ESS:

• SMC/DMC advantages:

  • Lightweight.

  • Higher impact resistance.

  • Flexible shapes and custom moulding.

  • Better in environments with vibration.

• Ceramic advantages:

  • Superior heat resistance.

  • Very high dielectric strength.

  • Good in extremely high-temperature environments.

• Trade-offs:
  Ceramic is heavier and more fragile. SMC/DMC can be more cost-effective and easier to install.

Recommendation: For most ESS, SMC/DMC insulators offer a balance of safety, performance, and cost. Ceramic is preferred for very high temperature or specialized applications.

Conclusion

Low voltage insulators are critical for electrical safety in energy storage. They not only separate conductors but also provide mechanical support, resist harsh environments, and ensure compliance with international standards.

From low voltage standoff insulators to busbar insulators, the right choice depends on voltage, mechanical load, material performance, and environmental conditions.

By following standards such as IEC 60660, IEC 60865, UL 94, GB/T 11022 and selecting the correct electrical insulation materials, designers can create reliable and safe ESS systems. Whether you choose SMC/DMC insulators or ceramic types, proper design and installation will extend the system’s lifespan and reduce risks.

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