Control transformers move fast. When a panel needs a 480V to 120V coil supply or a 24V control circuit, we can usually turn that around quickly. Distribution, buck-boost, and specialty types also available. Send the kVA, primary/secondary voltage, and mounting style for a quote.
Control transformers are one of the highest-velocity items in industrial electrical. They fail, they get dropped, they get swapped in during retrofits, and panels go through them regularly. The common configurations are 480V or 240V primary stepping down to 120V or 24V secondary, with VA ratings that typically run 50VA through 10kVA for panel-mount applications.
Mounting options include open-frame (foot-mount), H-bracket (DIN-rail adjacent or subpanel mount), and NEMA 1 enclosed. Most control transformers are 2-coil, but 3-coil versions with a separate primary disconnect winding appear in some PLC and relay logic panels. If the catalog number is on the nameplate, that's the cleanest way to get a quote. If not, the primary/secondary voltage and VA rating will usually get us there.
Condition is disclosed clearly with every quote. New, surplus, and reconditioned stock all appear depending on the catalog number and availability.
These are the brands that appear most frequently on quotes. Coverage spans control transformers, dry-type distribution, and buck-boost across a range of VA and kVA ratings.
One of the most referenced names in industrial control transformers. The T and TA series cover a wide VA/kVA range with both open-frame and enclosed options. Catalog numbers are alphanumeric and reference VA, primary, and secondary voltages directly.
The 9T catalog covers control, distribution, and specialty transformers. Panel builders familiar with Square D switchgear and MCCs often specify 9T transformers to maintain a consistent vendor. Mounting options and VA ranges are broad.
Eaton's QD and QDX lines serve control transformer applications from 50VA through several kVA. Frequently specified in Eaton MCC builds and standalone control panels. The QDX designation typically indicates an enclosed version.
Hammond is a well-regarded manufacturer for both control and distribution transformer applications. Their SBE and SHE series appear in panel builds across petrochemical, utilities, and general industrial. Wider kVA range than some competitors in certain footprints.
Sola and Hevi-Duty are often cited interchangeably; the Hevi-Duty brand name was absorbed over time. The SB and E-series control transformers are particularly common in older panel builds. Surplus stock for discontinued Hevi-Duty part numbers comes up periodically.
Dry-type distribution transformers for industrial applications run 480V delta primary to 208/120V wye secondary in the standard configuration. That covers the majority of building service and MCC room applications. Other primary/secondary combinations are available depending on catalog.
K-factor ratings matter in facilities with significant VFD, UPS, or non-linear load content. A K-4 is typical for mixed industrial; K-13 handles heavier harmonic environments. Specifying K-factor when it's a known requirement avoids a do-over at startup.
Ventilated vs. non-ventilated is an enclosure decision that depends on the installation environment. NEMA 3R is the standard for outdoor or wash-down adjacent locations. Anything going into an MCC room or enclosed electrical room is typically ventilated NEMA 1 unless there's a moisture concern.
| Parameter | Typical Range / Options |
|---|---|
| kVA range | 15 kVA to 1000 kVA |
| Standard voltage | 480V delta to 208/120V wye |
| Phases | 3-phase |
| K-factor | K-1 (standard), K-4, K-13 |
| Enclosure | Ventilated, non-ventilated, NEMA 3R |
| Insulation class | 220°C (Class H) standard |
| Temperature rise | 115°C or 80°C common |
Buck-boost transformers are autotransformers wired to raise or lower supply voltage by a small percentage, typically to correct a 208V to 240V mismatch, compensate for voltage drop over long runs, or adapt equipment rated for one leg voltage to available supply.
They're significantly smaller and less expensive than isolation transformers for the same load because they're only transforming the portion of voltage being added or subtracted, not the total power. Standard ratios cover the most common voltage adjustment requirements.
If you're not sure whether a buck-boost is the right fix for your application, include the incoming measured voltage, the load nameplate voltage, and the load kVA or amperage in your inquiry.
For control transformers, the catalog number off the nameplate is the fastest path. For distribution, we'll need a few more parameters. The list below covers the typical information that determines fitment, lead time, and price.
If a transformer is going into an existing panel or replacing a failed unit, photos of the nameplate help catch any secondary items like terminal configurations or mounting brackets that affect the swap.
Use the quote form for the cleanest path. You can attach a nameplate photo, spec sheet, or drawing. For quick questions, email or call directly.
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