Product Overview

The HET 25kVA exciter transformer is engineered for precision high-voltage testing with dual-range outputs (12.5kV/6.25kV). Featuring ultra-low partial discharge (<2pC) and advanced electrostatic shielding, it complies with IEC 60076-11 for dielectric testing in high-voltage laboratories and industrial facilities.

Electrical Specifications

Advanced Protection Systems

1. Overvoltage Protection

• Piezoresistors on all HV outputs

• Zinc oxide arresters (IEC 60099-4 compliant)

• Ground-connected via 15kA surge arresters

2. Insulation & Discharge Control

• 12.5kV corona-free HV bushings

• Electrostatic shield layer between HV windings

• Isovolumetric capacitance cores for stable voltage gradient

Mechanical Construction

Enclosure Features

• Steel housing with epoxy powder coating

• Wheel-mounted (4× heavy-duty casters)

• Shell-type oil tank with 40L conservator

Terminal Configuration

• LV terminals: Porcelain bushings

• HV terminals: Fiberglass-reinforced bushings

• Dual corona rings per HV bushing

Winding Technology

Advanced Insulation

• Cylinder-type winding with balanced top/bottom capacitance

• Inter-turn insulation (1.2mm Nomex® layers)

• Electrostatic compensation shields for uniform voltage distribution

Dielectric Performance

• Impulse withstand: 150kV (1.2/50μs wave)

• Power frequency withstand: 30kV/min

• Partial discharge <2pC at 1.1Ur

Installation & Maintenance

Commissioning Requirements

• Minimum 1.5m clearance from grounded objects

• Oil dielectric strength ≥55kV before energization

• Initial insulation resistance ≥12,000MΩ

Service Schedule

• Semi-annual oil testing (BDV, moisture content)

• Bushing inspection every 3 months

• Winding resistance test every 5,000 operating hours

Typical Applications

• Power transformer factory acceptance tests

• GIS (Gas Insulated Switchgear) commissioning

• High-voltage cable partial discharge measurement

• Rotating machine insulation diagnostics