INDUSTRY COMPONENT

Fixed Contacts (Tap Contacts)

Stationary electrical contacts in diverter switches for On-Load Tap Changers (OLTC) that maintain connection during tap changes.

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Component Specifications

Definition
Fixed contacts, also known as tap contacts, are stationary conductive components in diverter switches for On-Load Tap Changers (OLTC) in power transformers. They provide stable electrical connection points that remain stationary while moving contacts transition between them during tap changes, ensuring continuous power flow without interruption. These contacts are precisely positioned to correspond with specific transformer winding taps, enabling voltage regulation under load conditions.
Working Principle
Fixed contacts maintain constant electrical connection to transformer winding taps. When the diverter switch operates, moving contacts slide or rotate between fixed contacts, transferring the load current from one tap to another without breaking the circuit. The fixed contacts provide stable termination points with low contact resistance and reliable arcing management during transition.
Materials
High-conductivity copper alloys (C11000, C18150) with silver plating (Ag 99.9%, 5-15μm thickness), sometimes with tungsten or silver-tungsten composite for arc resistance. Insulation supports made of glass-reinforced epoxy or thermoset plastics.
Technical Parameters
  • Contact Force 20-100N
  • Rated Current 200-3000A
  • Rated Voltage 10-500kV
  • Mechanical Life >500,000 operations
  • Contact Resistance <15μΩ
  • Temperature Rating -40°C to +125°C
  • Insulation Resistance >1000MΩ
Standards
IEC 60214, IEEE C57.131, DIN VDE 0532

Industry Taxonomies & Aliases

Commonly used trade names and technical identifiers for Fixed Contacts (Tap Contacts).

fixed contacts tap contacts diverter switch contacts OLTC components transformer tap changers electrical contacts power transformer parts stationary contacts Fixed Contacts (Tap Contacts) Fixed Contacts (Tap Contacts) in Electrical Equipment Manufacturing

Parent Products

This component is used in the following industrial products

Diverter Switch (for OLTC)

A switching device within an On-Load Tap Changer (OLTC) that redirects current flow between transformer winding taps to adjust voltage without interrupting power.

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Engineering Analysis

Risks & Mitigation
  • Contact erosion from arcing
  • Oxidation increasing resistance
  • Mechanical deformation from thermal cycling
  • Insulation degradation
  • Misalignment causing improper contact
FMEA Triads
Trigger: Arcing during tap transitions
Failure: Contact surface erosion and pitting
Mitigation: Use arc-resistant materials (silver-tungsten), proper contact geometry, and vacuum or oil immersion
Trigger: Thermal cycling and overload
Failure: Contact material softening and deformation
Mitigation: Adequate thermal design, current derating, and temperature monitoring
Trigger: Environmental contamination
Failure: Increased contact resistance and overheating
Mitigation: Sealed enclosures, protective coatings, and regular maintenance

Industrial Ecosystem

Compatible With

Interchangeable Parts

Compliance & Inspection

Tolerance
Positional tolerance ±0.1mm, flatness <0.05mm, surface roughness Ra 0.4-0.8μm
Test Method
Contact resistance measurement (4-wire method), dielectric withstand test, mechanical endurance testing, thermal cycling tests

Procurement Evaluation Criteria

Not customer reviews or live demand data. These dimensions support RFQ preparation and supplier evaluation.

Technical documentation
4/5
Manufacturing capability
4/5
Inspection readiness
5/5
Supplier transparency
3/5

These scores are example evaluation dimensions, not real customer ratings, country-specific buyer feedback, or live inquiry activity.

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Frequently Asked Questions

What is the purpose of fixed contacts in diverter switches?

Fixed contacts provide stable connection points to transformer winding taps, allowing moving contacts to transition between them without interrupting power flow during voltage regulation.

How do fixed contacts differ from moving contacts in OLTC systems?

Fixed contacts remain stationary and are permanently connected to specific transformer taps, while moving contacts physically transition between fixed contacts to change the active tap connection.

What maintenance do fixed contacts require?

Regular inspection for wear, pitting, oxidation, and contact resistance measurement. Cleaning and silver re-plating may be needed after extensive operations.

Can I contact factories directly?

Yes, each factory profile provides direct contact information.

Data Basis

CNFX manufacturer profiles, technical classification, publicly available product information, and ongoing plausibility checks.

Preliminary Technical Classification
This page supports structured research, RFQ preparation, and supplier evaluation. It does not replace buyer-led supplier qualification, standards review, or technical approval.

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