Station Post Insulators IEC C4-125
A porcelain station post insulator designed to IEC C4-125 standards for use in substations and switchgear applications. The insulator provides electrical insulation and mechanical support for busbars and disconnectors. It is suitable for indoor and outdoor installations where high mechanical and electrical strength is required. The design supports system voltages up to 125kV AC as defined by the IEC standard.
Key Benefits
- IEC C4-125 standard design ensures compatibility with international substation specifications
- 4kN cantilever strength supports rigid mounting under dynamic load conditions
- 500mm creepage distance provides reliable performance in polluted environments
- 60kV dry withstand voltage and 50kV wet withstand voltage meet IEC power frequency requirements
- 125kV lightning impulse withstand voltage ensures protection against transient overvoltages
- Porcelain body resists tracking and erosion under long-term electrical stress
Technical Features
- IEC C4-125 standard design for substation applications
- 130mm diameter body with 305mm height for compact installation
- 500mm creepage distance supports performance in polluted and coastal environments
- 4kN cantilever strength for rigid mounting under mechanical stress
- 800N-m tensile strength for resistance to bending and torsional loads
- 50kV power frequency wet withstand voltage for reliable insulation under wet conditions
- 60kV power frequency dry withstand voltage for insulation under dry conditions
- 125kV lightning impulse withstand voltage for protection against transient overvoltages
- IEC C4 125
- STATION POST INSULATORS
- HIGH VOLTAGE INSULATORS
Specifications
| IEC Standard | C4-125 |
|---|---|
| Diameter (D) | 130mm |
| Height (H) | 305mm |
| Creepage Distance | 500mm |
| Cantilever Strength | 4kN |
| Tensile Strength | 800N-m |
| Power Frequency Wet Withstand Voltage | 50kV |
| Power Frequency Dry Withstand Voltage | 60kV |
| Lightning Impulse Withstand Voltage | 125kV |
Figures are the published design values for this class. Imperial and metric are the same part. Download this table as a PDF datasheet.
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Who It Is For and What It Solves
Who It Is For
- Substation builders specifying insulators for switchgear and busbar systems
- Utility procurement engineers sourcing IEC-standard station insulators
- EPC contractors specifying components for substation packages
- Electrical wholesalers supplying station equipment to regional utilities
- Maintenance teams replacing insulators in existing substation installations
Problems It Solves
- Mismatched insulator standards in international projects where IEC compliance is required
- Insufficient creepage distance leading to flashover in polluted or humid environments
- Mechanical failure under cantilever load due to low strength in standard post insulators
- Lack of reliable impulse withstand capability in insulators not tested to IEC lightning standards
- Difficulty in sourcing insulators with exact IEC C4-125 dimensions and ratings
Application Scenarios
- Mounting busbars in indoor and outdoor substations where mechanical rigidity is required
- Supporting disconnectors and isolators in high-voltage switchgear assemblies
- Installing in substations located in coastal or industrial areas with high pollution levels
- Replacing aging insulators in existing switchgear where IEC C4-125 is the required standard
- Use in new substation builds where IEC-compliant station post insulators are specified
Materials and Manufacture
Materials
- Glazed electrical porcelain dielectric body
- Galvanized steel or forged steel metal fittings
- Portland cement bonding the metal fittings to the porcelain
Manufacturing Steps
Body preparation and forming of the porcelain shell
Glazing and high temperature firing to achieve surface hardness and dielectric strength
Cementing of the metal fittings to the porcelain body
Final dimensional and visual inspection before packaging
Electrical and mechanical testing in accordance with IEC C4-125 requirements
Quality Control
- Manufactured under an ISO 9001:2008 certified quality system
- Mechanical and electrical performance verified against the IEC C4-125 design ratings
- Creepage distance measured against the 500mm specification
- Cantilever and tensile strength tested to meet the 4kN and 800N-m ratings
- Power frequency wet and dry withstand voltages tested to 50kV and 60kV respectively
- Lightning impulse withstand voltage tested to 125kV
Certification held: ISO 9001:2008. No other certification is claimed.
Customization Options
- Glaze colour to match utility or project specification
- Alternative metal fittings for specific mechanical or corrosion resistance needs
- Non-standard dimensions or ratings developed with our engineers for a specific application
- Special packaging for transport and handling in high-risk environments
No Published Class Fits
We design insulators for specific non-standard applications. Send the mounting interface, the mechanical duty and the system voltage and our engineers will work through it with you.
Compared With the Alternatives
| Pin type insulators | Station post insulators are bolted rigidly to a substation structure while pin type insulators are mounted on a pin or spindle on a distribution pole crossarm |
|---|---|
| Polymer insulators | Porcelain offers better long-term resistance to UV and pollution tracking but is heavier and more brittle than polymer |
| Suspension insulators | Station post insulators are fixed and rigid while suspension insulators allow conductor movement; they are used in different structural roles |
Use Guide
Verify the system voltage and pollution level before selecting the insulator
Ensure the mounting hardware matches the insulator's metal fitting dimensions
Do not exceed the 4kN cantilever strength under dynamic or wind load conditions
Inspect for glaze cracks or cement damage before installation
Handle by the metal fittings to avoid stress on the porcelain body
Station Post Insulators IEC C4-125 FAQ
What is the IEC standard for this insulator
This insulator is designed to IEC C4-125, which defines the mechanical and electrical performance for station post insulators.
What is the maximum mechanical load this insulator can support
The cantilever strength is 4kN. Do not exceed this value under dynamic or wind load conditions.
Is this insulator rated for outdoor use
Yes. The 500mm creepage distance and glazed porcelain body make it suitable for outdoor substations, including polluted and coastal environments.
Can you supply a non-standard version for our project
Yes. We design insulators for specific non-standard applications and our engineers are available to assist with custom development.
What is the wet withstand voltage rating
The power frequency wet withstand voltage is 50kV, as defined by the IEC C4-125 standard.
What certification do you hold
Our manufacturing facilities are certified to ISO 9001:2008. We do not claim any other certification on this page.
What is the minimum order quantity
MOQ depends on the glaze colour and the specific IEC class. Email us with the class and quantity and we will confirm.
Guides That Cover This Product
ANSI and IEC Porcelain Insulator Standards Compared
How ANSI classes like 52-4 and 57-2 and IEC designations like C4-125 describe a porcelain insulator, and what to check o
How to Read ANSI Insulator Class Numbers
Learn how ANSI class numbers like 52-4, 56-3 and 57-2 identify porcelain insulators, and how they differ from IEC design
Creepage Distance and Pollution Performance
Creepage distance values for IEC C4-125 (500mm), ANSI TR-208 (610mm), ANSI 57-2 (559mm), and ANSI 56-3 (533mm) insulator
Quote Station Post Insulators IEC C4-125
Send the quantity, the coupling type and the destination and we will quote against the published figures on this page. The datasheet PDF has the same table.