Product Overview

The HET 40kVA exciter transformer offers three voltage outputs (4kV/2.5kV/1.5kV) through a manual tap-changer, with ONAN cooling and 25# transformer oil insulation. Designed for flexible testing applications with <6% impedance voltage.

Electrical Specifications

Key Features

Manual Tap-Changer System

• Three-position rotary switch for voltage selection

• Mechanical interlock prevents live switching

• Visual position indicator for tap confirmation

Thermal Performance

• ONAN cooling with 25# transformer oil

• Continuous operation at full rated capacity

• Winding temperature rise ≤65K

Protection Systems

1. Overvoltage Protection

• Piezoresistors on all HV outputs

• Zinc oxide arresters (15kA rating) per IEC 60099-4

• Dual ground reference points

2. Insulation Control

• Electrostatic shielding between all windings

• 4kV corona-free fiberglass bushings

• Isovolumetric capacitance cores in HV bushings

Mechanical Design

Enclosure Features

• 14-gauge steel housing with corrosion-resistant coating

• Integrated wheel base (4× 200mm industrial casters)

• Shell-type oil tank with 45L conservator

Terminal Configuration

• LV terminals: Porcelain bushings (0.38kV input)

• HV terminals: Fiberglass-reinforced epoxy bushings

• All bushings feature dual corona rings

Winding Technology

• Cylinder-type windings with balanced capacitance

• Electrostatic compensation shields

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

• Compound insulation tubes for partial discharge control

Installation & Maintenance

Commissioning Requirements

• Minimum 1m clearance from grounded surfaces

• Initial oil BDV ≥40kV (2.5mm gap)

• Verify tap-changer position before energization

Service Schedule

• Monthly: Inspect tap-changer contacts

• Quarterly: Oil dielectric testing

• Annual: Complete winding resistance test

Typical Applications

• Multi-voltage cable testing systems

• Circuit breaker contact resistance testing

• Rotating machine insulation diagnostics

• Transformer factory acceptance tests