Product Overview

The HET 25kVA exciter transformer delivers precision high-voltage testing with dual-range outputs (8kV/4kV) and ONAN cooling. Designed for industrial applications, it complies with IEC 60076-11 and features advanced electrostatic shielding for stable dielectric performance.

Electrical Parameters

Advanced Protection Systems

1. Overvoltage Protection

• Piezoresistors on all HV outputs

• Zinc oxide arresters (IEC 60099-4 compliant)

• Ground-connected terminals via 10kA surge arresters

2. Insulation & Discharge Control

• 8kV corona-free HV bushings

• Electrostatic shield layer between HV windings

• Isovolumetric capacitance cores for voltage stability

Mechanical Construction

Enclosure Design

• Steel housing with anti-corrosion coating

• Wheel-mounted (4× industrial casters)

• Shell-type oil tank with 30L conservator

Terminal Configuration

• LV terminals: Porcelain bushings

• HV terminals: Fiberglass-reinforced bushings

• Dual corona rings per HV bushing

Winding Technology

Insulation System

• Cylinder-type winding with balanced capacitance

• Inter-turn insulation (1mm Nomex® layers)

• Electrostatic compensation shields for uniform voltage distribution

Dielectric Performance

• Partial discharge <5pC at 1.1Ur (IEC 60270)

• Impulse withstand: 95kV (1.2/50μs wave)

• Power frequency withstand: 18kV/min

Installation & Maintenance

Commissioning Requirements

• Minimum 1m clearance from grounded surfaces

• Oil dielectric strength ≥45kV before energization

• Initial insulation resistance ≥8,000MΩ

Service Schedule

• Annual oil testing (breakdown voltage, acidity)

• Bushing inspection every 6 months

• Winding resistance measurement every 3,000 hours

Typical Applications

• Power transformer routine testing

• Cable fault location systems

• Rotating machine insulation tests

• High-voltage component R&D