Zinc Oxide Resistor Block | Surge Arrester Core Component

The zinc oxide (ZnO) resistor block is the core nonlinear element used in metal oxide surge arresters (MOA) for overvoltage protection in power systems. It functions by clamping surge voltages while offering high resistance under normal voltage and low resistance during overvoltage conditions.

These ceramic discs are manufactured through a high-temperature sintering process, forming a dense microstructure that ensures excellent energy absorption, long-term stability, and high discharge capacity.

🔧 Key Features

High nonlinearity coefficient (α > 30)
Excellent energy absorption performance
Stable electrical characteristics across temperature & humidity ranges
Customizable diameter, thickness, voltage level
Crack-free surface, tight tolerance dimensions
Compatible with IEC and GB-class arresters

📐 Technical Specifications

Parameter	Value
Rated Voltage Class	3kV–220kV
Nominal Discharge Current	5kA / 10kA
Residual Voltage Ratio (Ures/Un)	≤ 2.6
Leakage Current	≤ 20μA
Energy Absorption Capacity	2kJ/cm³ – 4kJ/cm³
Insulation Resistance	≥ 1000MΩ
Surface Finish	Glazed, anti-moisture
Standard Sizes	Diameter: 20–115mm; Thickness: 2–20mm

✅ Compliance & Standards

IEC 60099-4 – Metal-oxide surge arresters without gaps
GB/T 11032 – AC gapless metal oxide surge arresters
Raw materials and finished products comply with ISO 9001
RoHS and environmental regulations compliant

🧰 Typical Applications

Core components for ZnO surge arresters
Installed in 10kV–220kV class arresters for substations, distribution lines, and wind farms
Suitable for both polymer and porcelain-housed arresters
Used in IEC/ANSI standard products

🌍 Real Case Example: OEM Supply to Brazil Arrester Manufacturer (2023)

In 2023, over 80,000 zinc oxide resistor blocks were delivered to a Brazilian surge arrester OEM. These units were designed for 24kV polymer-housed arresters with 10kA nominal discharge current, providing stable clamping at 65kV residual voltage and tested under IEC 60099-4 standards.

• Maintained ±5% tolerance in clamping voltage
• Passed 1000-hour accelerated aging test
• Enabled local clients to meet ANEEL certification requirements

❓ Frequently Asked Questions (FAQ)

• What is the function of a zinc oxide resistor in surge arresters?
It absorbs and clamps overvoltage surges to protect power equipment.

• How is this different from silicon carbide (SiC) blocks?
ZnO resistors offer superior nonlinearity and do not require series gaps, making them more reliable.

• Can the size and voltage rating be customized?
Yes. Both diameter and thickness can be customized according to voltage class and energy requirements.

• Is surface glazing necessary?
Yes. Glazing prevents moisture absorption and surface tracking, improving long-term performance.

• What standards should a ZnO resistor meet?
It should comply with IEC 60099-4 or GB/T 11032, depending on region and application.