Replacement sourcing for discontinued dry-type transformers: Acme T, TA, TF, and TFS series; Federal Pacific FP series; GE 9T series; Westinghouse older dry-type; Sorgel and General Signal control transformers. Odd voltages and non-standard mounting configurations sourced. Condition disclosed with every quote.
When a dry-type distribution transformer fails, the straightforward assumption is that any transformer with the matching kVA rating and voltage will drop in as a replacement. In a plant with equipment installed before 1985, that assumption is frequently wrong. Old dry-type transformers from Federal Pacific, Acme, or Westinghouse were built to form factors that don't align with modern catalog dimensions. The mounting hole pattern may be 12 inches on center instead of the current standard. The terminal strip may be on the opposite side of the enclosure. The primary lead labeling may follow a different convention than current ANSI standards.
Physical fitment matters before electrical ratings even come into play. A 45 kVA 480-to-208/120V three-phase transformer that is two inches taller than the original won't clear the overhead clearance in the existing transformer vault. A unit with terminals on the right side cannot replace one with terminals on the left without re-routing conduit. Identifying these constraints before ordering a replacement saves significant time and cost.
Edmundson Industrial sources legacy and discontinued transformer units. For some obsolete series, we locate existing old-stock or surplus units from the original series to preserve physical compatibility. For others, a buck-boost approach or a custom-ordered unit may resolve the dimensional problem. We don't provide engineering services, but we can tell you what we can source and provide the nameplate data to help your engineer make the fitment determination.
Items are sourced new, surplus, or reconditioned, with condition disclosed clearly with every quote. Reconditioned dry-type transformers should have test documentation reviewed before installation in sensitive applications.
Each of these manufacturer lines has been discontinued, acquired, or absorbed. The physical units remain in service in industrial plants across the United States. When a nameplate from one of these series comes in on a sourcing request, these are the details we need.
Acme Electric produced one of the broadest lines of dry-type distribution and control transformers in North America. The T series covered general-purpose single-phase distribution; the TA and TFS series covered three-phase distribution units. The TF series covered smaller control and isolation transformers. Acme was acquired through various ownership changes and the older series catalog numbers are no longer in active production. Catalog numbers from the Acme T, TA, TF, and TFS series are used for surplus identification. The full catalog number is on the nameplate and includes the series designation, kVA rating, and voltage configuration encoding.
Federal Pacific Electric produced a wide range of dry-type distribution transformers primarily for commercial and industrial applications. The FP series transformers are encountered frequently in older industrial plants, particularly in the Gulf Coast region. Federal Pacific's transformer product line (distinct from the Stab-Lok breaker issues) was well-regarded, and many FP transformers are still in active service. The company was eventually acquired; newer parent-company versions of the transformer line use different catalog numbering. The original FP nameplate catalog number is the most reliable identifier for sourcing a compatible replacement.
GE's 9T series dry-type transformer line covered distribution and control applications across a wide kVA range. GE's older cast coil transformer designs (encapsulated winding construction) are found in particularly demanding environments where moisture, vibration, or contamination ruled out conventional dry-type. GE's industrial transformer business was divested and the 9T series numbering was carried forward under the new ownership for a period, creating some naming overlap. Older GE 9T units with cast coil windings or legacy terminal configurations require the original nameplate data for accurate sourcing.
Westinghouse dry-type distribution transformers are found in older refinery, chemical, and heavy manufacturing facilities, particularly in facilities built between the 1950s and the 1980s. The W-series naming convention covers the older Westinghouse dry-type distribution line. After Westinghouse's acquisition by CBS and subsequent industrial asset sales, the transformer product lines were transitioned. Older Westinghouse transformers often have non-standard terminal arrangements and mounting configurations that reflect the manufacturing standards of their era rather than current ANSI dimensional standards.
Sorgel (later General Signal) produced a widely installed line of control transformers and isolation transformers for industrial panel and machine applications. Sorgel control transformers are found in older machine tool, process control, and panel enclosure applications throughout the industrial Midwest and Gulf Coast. The Sorgel catalog numbering scheme encodes the VA rating, primary voltage, and secondary voltage in the catalog number. These transformers are long out of production, and replacements come from surplus stock. Providing the original Sorgel catalog number from the nameplate is the most efficient identification method.
Marcus Transformer and Rex Manufacturing produced specialty and general-purpose dry-type transformers for industrial and commercial applications. Both brands are encountered in older plant installations, less commonly than Acme or Federal Pacific but present enough to generate replacement requests. Sourcing for these brands is entirely secondary market. The nameplate catalog number, kVA rating, primary and secondary voltages, and a photo of the physical unit are needed to attempt to locate a compatible replacement.
Buck-boost transformers adjust voltage by a small percentage rather than providing full isolation at a different voltage ratio. They are used to correct for nominal system voltage mismatches: boosting 208V to 230V, boosting 440V to 480V, or bucking 480V down to 460V or 440V. Single-phase configurations cover common VA ratings from 0.1 kVA through about 10 kVA; three-phase bank configurations extend higher using single-phase units connected in an additive or subtractive arrangement.
Buck-boost transformers solve the 440V legacy system problem cost-effectively. A facility with a 440V main distribution system can use a buck-boost transformer to supply 480V to a new piece of equipment without reconfiguring the main distribution transformer. Specify the input voltage, desired output voltage, single-phase or three-phase, and kVA load.
Control transformers supply the control circuit voltage for motor starters, relays, solenoid valves, and panel logic. The most common configuration is 480V primary to 120V secondary. Secondary voltages of 24V AC are also common in newer control schemes. VA ratings for panel control transformers run from 50VA through about 3 kVA for most applications. Primary voltage taps at both 480V and 240V are common on dual-primary units.
Mounting configurations matter for panel replacement work. H-bracket (panel-mount) control transformers are foot-mounted to the back pan of an enclosure. Some older control transformers use a flush-mount or chassis-mount style that has no direct modern equivalent. When replacing an older control transformer in an existing panel, specifying the mounting style and the available panel space avoids ordering a unit that doesn't fit the existing mounting hardware.
Isolation transformers have a 1:1 voltage ratio and provide a separately derived system with no direct connection between primary and secondary. They are used for noise isolation in sensitive instrumentation circuits, ground loop elimination between equipment at different potential, and safety isolation in certain medical or laboratory environments. Single-phase isolation transformers from 0.5 kVA through 15 kVA are the most commonly requested. Three-phase isolation transformers for larger loads are also sourced. The key specification beyond kVA and voltage is the isolation level, expressed as the withstand voltage rating between primary and secondary.
Autotransformers use a tapped single winding rather than separate primary and secondary windings. They are used for reduced-voltage starting of large motors (the most common industrial application) and for single-ratio voltage adjustment. Autotransformers are not isolation transformers; there is a direct electrical connection between primary and secondary. For reduced-voltage starting, the autotransformer is used in combination with a dedicated starting circuit, often in a Korndorfer connection. Specify the motor HP, voltage, frequency, and starting tap percentage (typically 65%, 80%, or 100% of full voltage).
Dry-type distribution transformers step down the main distribution voltage to utilization voltage for branch circuits and equipment feeds. Common configurations are 480V-to-208/120V three-phase for office and mixed loads, and 480V-to-240/120V single-phase for residential-type loads in industrial buildings. Legacy primary voltages of 440V, 550V, and 575V are found on older equipment where the main system predates the current 480V nominal standard. A 440V-primary transformer does not accept a direct 480V feed without running above rated voltage; this is the scenario where a buck-boost transformer is often the practical correction.
440V and 550V legacy systems: Equipment installed before the industry-wide transition to 480V nominal often runs on 440V or 550V distribution systems. A modern 480V transformer with a 480V primary tap will operate above nameplate voltage on a 440V system (the transformer runs at 440/480 = 91.7% of rated voltage, which is acceptable). But a modern 480V primary transformer connected to a 550V system runs at 550/480 = 114.6% of rated voltage, which will overheat the transformer. A buck-boost transformer or a custom 550V primary unit is required for 550V feeds.
Mounting patterns: Older dry-type transformers were manufactured to the dimensional standards of their era, which do not uniformly match current NEMA or ANSI dimensional standards for dry-type transformers. A Westinghouse or Federal Pacific unit from the 1960s may have mounting feet spaced at intervals that don't match any current catalog transformer. If the original transformer's mounting footprint is critical (vault floor anchors, existing structural supports), measure the existing unit before ordering a replacement. A surplus unit from the same original series preserves the mounting footprint; a new current-production unit may require modified mounting hardware.
Terminal orientation and lead labeling: Older transformers may label primary leads H1, H2, H3 and secondary leads X1, X2, X3 per ANSI standards, but the physical position of those terminals relative to the transformer body varied by manufacturer and era. Before assuming a replacement unit will accept the existing conduit entries, confirm the terminal side and position on the nameplate or from a manufacturer data sheet.
Reconditioned units: For larger kVA dry-type units where surplus new-old-stock is not available, reconditioned units are sometimes the practical option. Reconditioned transformers should have documented test results including insulation resistance, winding resistance, turns ratio, and excitation current. We disclose condition on every quote and note when test documentation is or is not available for a given unit.
The nameplate data is the starting point. A photo of the transformer nameplate is the most efficient way to convey the primary and secondary voltages, kVA rating, phase, frequency, and catalog number in a single submission. If the nameplate is not readable, collect as many of the following data points as possible from any available documentation.
For most requests, these are the critical fields. The more you provide, the more accurately we can identify a compatible replacement.
Email: sales@edmundsonindustrial.com
Phone: (832) 975-8827