partial-discharge | Subs'tionReliability

Partial Discharge Inspections

Reliability-centered substation maintenance is built on gathering and analyzing as much condition data as possible before assets fail - enter partial discharge testing.

Partial discharge (PD) testing has delivered significant cost savings for SDMyers customers and protected their power transformers, switchgear, high voltage cable systems, and other electrical equipment from avoidable downtime.

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PD Testing with No Downtime

Whether you're managing pad-mounted transformers, substation gear, or other high-voltage equipment, Partial Discharge (PD) inspections help detect failure modes before they lead to costly downtime.

Learn how our team uses tools such as ultrasound parabolic dishes, contact probes, and Transient Earth Voltage (TEV) sensors to detect internal discharge threats—without powering down your system.

How do PD inspections find failure modes so early?

PD inspections can help confirm transformer oil testing results or serve as a standalone detection technique for failure modes such as:

Insulation deterioration
Arcing/electrical discharges
Breakdown in transformer insulating liquid

Partial discharge inspections can pinpoint electrical issues in your network early, before they lead to catastrophic failure. Partial discharges emit energy in several ways: electrical pulse currents, dielectric losses, light, sound, increased gas pressure, and chemical reactions. Based on the energy emitted, multiple detection methods exist, such as Ultrasound and Transient Earth Voltage (TEV).

Ultrasound, the first line of defense, relies on changes in ultrasonic wave patterns. These can be detected long before other preventive maintenance tests detect other indicators.

TRACKING

A surface discharge that builds a conducive path across the surface allowing the condition to grow and and lead to an eventual failure.

CORONA

The air around a connection becomes ionized and starts to break down the Oxygen into Nitrogen Oxide, leaving a residue on the connections and insulators that can change to Nitric Acid with exposure to humidity and water.

TREEING

The continuous impact of partial discharges in solid dielectrics from the breakdown area forms discharge channels which grow in a tree-like formation.

SURFACE DISCHARGE

Appears at the boundary of different insulation materials.

INTERNAL DISCHARGE

Occurs in voids or cavities within solid or liquid dielectrics.

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Partial Discharge Inspections

PD Testing with No Downtime

How do PD inspections find failure modes so early?