Power Factor / Dissipation Factor (Tan Delta) Measurements on Instrument Transformers

An insulation failure is often the reason for an instrument transformer (IT) malfunction.

Factors which possibly accelerate the insulation's aging process:

Moisture ingression due to broken seals
Heat caused by the ambient temperature or sunlight

Older insulation can lead to high losses in the IT, which generates further heat. Since ITs are not actively cooled, old or degraded insulation can result in a failure or even an explosion. Fragments from the explosion represent a serious hazard for persons in the substation as well as for surrounding equipment.

Dissipation/power factor (tan(δ) delta) measurements help you determine the insulation condition. When using our testing systems, you will also be able to determine the dissipation factor at various frequencies and detect any signs of aging at an early stage. Thus, an IT can be replaced before any further damage occurs.

Benefits of this solution

High level of mobility

The CPX 200 + HVX10 combination is a compact, lightweight, and powerful test system for high and medium voltage assets, weighing less than 30 kg (66 lbs). The combo is designed for easy transport and handling, making it ideal for on-site substation testing.

One system – multiple tests

The CPX 200 + HVX10 combo offers you the best of both worlds by integrating insulation resistance with capacitance and power factor/dissipation factor testing in a single unit and setup.

Increased measurement sensitivity

With CPX 200 + HVX 10, the 1 Hz to 600 Hz frequency sweep increases the test’s sensitivity, supporting your insulation condition assessments and enabling the detection of defects at an early stage.

DIRANA + PTM

DIRANA uses Dielectric Frequency Response (DFR) analysis to assess the condition of power transformer insulation systems. It measures capacitance and the power factor/dissipation factor across a wide frequency range, from 10 µHz to 5 kHz, at a maximum output voltage of 200 V ^peak.

This measurement not only provides information about the insulation system's moisture content and oil conductivity, but also delivers additional valuable parameters such as insulation resistance, polarization index (PI), and dielectric absorption ratio (DAR).