AMKA Engineering / Partial Discharge Testing

Partial discharge testing, on live switchgear.

Insulation fails quietly before it fails loudly. TEV and airborne ultrasound read the discharge through the closed panel — no shutdown, nothing opened — and every finding arrives severity-rated, in writing.

This screens the insulation-discharge path. It is a different question from the one thermography answers, which reads heat around current-carrying connections. Neither substitutes for the other, and the Electrical Health Assessment runs both against the same asset list. Not yet sure which method the asset needs? Start from electrical inspection and condition monitoring.

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Partial discharge screening What is discharging inside the switchgear right now?

TEV Internal discharge Read through the panel metal itself

Ultrasound Surface & airborne discharge Heard at the joints and seams

01 / What the screen reads

Three kinds of discharge. Two channels.

Partial discharge is insulation breaking down in place — and it announces itself in sound and voltage transients long before it announces itself in smoke.

Internal discharge

Inside the insulation

Voids and terminations discharging where nothing can be seen — picked up as transient earth voltages (TEV) through the panel metal.

Surface discharge

Across the insulation

Tracking across aged or contaminated surfaces, heard on the ultrasound channel — the carbon trails below are its endpoint.

Corona

Into the air

Discharge at sharp edges and stressed points, heard ultrasonically — degrading everything around it long before anything fails.

02 / Heard, then seen

The readings come while the board stays closed.

A technician holding a TEV partial discharge detector against live 11 kV switchgear, the panel's danger label visible beside the instrument — FIG.01TEV, live 11 kV switchgear

TEV, through the metal

Internal discharge read from the panel surface — the 11 kV board stays closed, and stays live.

A technician wearing headphones using a flexible airborne ultrasound probe along closed switchgear panel joints — FIG.02Airborne ultrasound at the seams

Ultrasound, at the joints

Surface and airborne discharge heard along the panel openings while the equipment keeps running.

Carbonised electrical tracking spread across a busbar support and insulation barriers inside opened switchgear — FIG.03Discharge tracking, busbar support

What the sound looks like

Carbon tracking across a busbar support, photographed after opening — discharge that had been audible long before it was visible.

A severely arc-damaged, burnt circuit breaker removed from its panel, standing on the floor — FIG.04What a missed fault becomes

The aftermath

When insulation finally fails, it fails as an arc. Screening exists so a board never produces this.

03 / What the screening proves

Indications, rated — and the limits, stated.

Does the panel have to be opened?: No. TEV reads through the panel metal and ultrasound listens at the joints and seams. Opening happens only if a finding justifies a planned internal inspection.
What does a finding actually prove?: Readings are compared against severity thresholds and rated. Screening indicates that discharge activity exists and how serious it appears — it does not pinpoint the exact component inside a sealed compartment. That is what the planned follow-up is for.
Which equipment suits it?: MV and HV metal-clad switchgear, cable terminations and enclosed insulation systems. Where an asset does not suit the method, the proposal says so instead of testing it anyway. For 11kV boards specifically, we have written up what each instrument reveals on metal-clad gear.
What happens after a finding?: Monitor, retest, deepen the investigation, or plan corrective work — each a separate, quoted decision. A screening fee never quietly becomes a repair bill.

Before you decide

What the screening can and cannot settle.

Next step

Discharge is one of the two ways a board fails.

Heat at the connections is the other — and the Electrical Health Assessment reads both paths in one visit, on one evidence path. Name the switchgear, the operating concern and the urgency, and the free proposal sets the scope, boundaries and price in writing.

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