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Used Potential Transformers

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Overview

Potential transformers (PTs), also called voltage transformers, step down high system voltages to standardized, isolated levels for metering and protection. They deliver accurate proportional voltage outputs for meters, protection relays and control circuits in substations, switchgear and industrial plants. PTs are available as oil-filled or dry types, single- or three-phase designs, and vary by accuracy class, burden and rated voltage—select based on system voltage, protection needs and environment.

FAQ

What should I check when buying a used potential transformer?

Verify manufacturer, model, rated primary/secondary voltages, burden and accuracy class. Request nameplate data, insulation and ratio test records, oil test reports for oil-filled units, and any repair history to confirm suitability and condition.

How do I ship a potential transformer safely?

Use a carrier experienced with high-voltage equipment. De-energize and secure the unit, drain oil if required by regulations, protect bushings and tap changers, brace windings for transport, crate on proper skids, and insure the shipment.

What maintenance should I plan for after purchase?

Establish periodic visual inspections, insulation resistance and ratio tests, tighten connections, inspect bushings and seals, and perform oil sampling/DGA for oil-filled PTs. Follow manufacturer intervals and keep detailed test records.