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Used Square D Power Transformers

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Overview

Power transformers transfer electrical energy between voltage levels for utilities, substations, and large industrial plants. These heavy, high-capacity units come in oil-filled or dry-type designs, with cooling classes (ONAN, ONAF, etc.), on-load tap changers, bushings and protection gear. Buyers must match voltage class, impedance, capacity (kVA/MVA), and cooling to system needs, and plan for foundation, handling, transport and commissioning.

FAQ

What specifications should I check when buying a used power transformer?

Confirm voltage ratios, kVA/MVA rating, impedance, cooling type, phase configuration, on-load tap changer condition, bushing types and insulation class, and recent test reports (DGA, insulation resistance, turns ratio).

How do I verify a used transformer's condition before purchase?

Request factory and maintenance records, Dissolved Gas Analysis (DGA), insulation resistance, power factor tests, sweep-frequency response (SFRA) and a visual inspection report for leaks, rust and bushing integrity.

What are the key shipping considerations for heavy power transformers?

Plan for specialized heavy-haul transport, load lifting equipment, route permits, weight/axle limits, skidding or cradling, draining oil if required by regulations, and coordination with local authorities for oversized loads.

What site preparations are needed before delivery and installation?

Prepare a level, rated foundation or skid with proper anchoring, ensure crane access and pad capacity, verify cable entry, grounding, oil containment for liquid-filled units, and arrange for qualified rigging and electrical commissioning crews.

What ongoing maintenance keeps a power transformer reliable?

Perform regular DGA, insulation resistance and oil quality tests, thermographic inspections, tap changer maintenance, bushing checks, cooling system inspections and timely repairs. Follow manufacturer intervals and keep detailed service records.