What we buy
Ranges we buy on this page
Delta and wye describe how a three-phase transformer's windings connect, not how its tank looks. This guide explains the two connections, their effects on harmonics and grounding, and how to read them from a nameplate.
| Phase | kVA | Voltage | Fluid |
|---|---|---|---|
| 1-phase | 10 - 333 kVA | up to 25 kV | Liquid or dry |
| 3-phase | 50 - 20,000 kVA | 115 kV | Liquid or dry |
Who we buy from
Six kinds of seller
- Recyclers
- Electrical contractors
- Equipment dealers
- End users
- Demo contractors
- Distributors
Fast offers
A written offer the same business day, based on your photographs.
Dedicated logistics
Our own crew, trailer and crane, not a brokered haul.
No broker fees
One buyer from first call to cleared pad, with nothing skimmed.
How it works
Six steps from photograph to payment
- 01
Take pictures
Photograph the nameplate, the inside of the cabinet and the tank from both ends. Four frames on a phone are enough to price most units.
- 02
Send them to us
Email or text the photographs with the site address and whether the unit is still energised. We reply the same business day with questions or a number.
- 03
Review the offer
The offer names the unit, the site, the price and the pickup window. It is written, dated and good for thirty days unless the unit changes hands.
- 04
We schedule freight
A crew, a trailer and a crane if the pad needs one. You get the date and the arrival window, and the site does not have to close for it.
- 05
Testing on arrival
Winding resistance, insulation resistance and a turns ratio check, plus oil analysis where the unit is liquid-filled. Results travel with the unit.
- 06
Get paid
Payment is released against the signed bill of sale and the scale ticket, by check or ACH, with the paperwork copy left on site.
What we handle
The parts sellers dread
Rigging
Crane, skates and a route survey for anything that will not roll onto a trailer.
Oil containment
Pans, absorbent and a spill plan before a drain plug is touched.
Bill of sale
A document that clears a lien, a lease or a bankruptcy file, not a handwritten note.
PCB paperwork
Testing and manifesting for pre-1979 oil, handled before the unit moves.
On the ground
What it is
A delta connection joins three windings end to end in a closed triangle. Its three corners connect to the phase conductors, usually identified by H or X terminal markings.
A conventional three-wire delta has no neutral point, although some delta systems use grounding arrangements or a center tap.
A wye connection joins one end of each winding at a common point. When that point is brought out, it provides a neutral terminal, often marked X0 on the secondary.
A 480Y/277-volt nameplate identifies 480 volts between phases and 277 volts from phase to neutral.
Local reality
Why it matters when you sell
Connection determines whether a removed transformer matches another installation's conductors, neutral requirements, and grounding design. A 480-volt delta secondary is not interchangeable with a 480Y/277-volt secondary simply because their line voltages match.
Hospital lighting panels, for example, may require the 277-volt phase-to-neutral supply that the delta lacks.
Transformer Buyers NC buys used, surplus, failed, and obsolete transformers across North Carolina. For connection review, clear photographs of the nameplate, terminal diagram, and X0 bushing are more useful than a description such as three-phase.
Include any grounding resistor documentation and the site's one-line diagram when accessible.
Around the site
The numbers
In wye, line-to-line voltage equals winding voltage multiplied by the square root of three, approximately 1.732. Thus, each secondary winding of a 480Y/277-volt transformer operates at about 277 volts.
In delta, winding voltage equals line-to-line voltage; each winding in a 480-volt delta operates at 480 volts.
For balanced loads, wye line current equals winding current; delta line current equals winding current multiplied by approximately 1.732. Nameplate kVA describes the complete three-phase rating, not one winding.
A delta-wye connection commonly introduces a 30-degree phase displacement, but the connection diagram establishes its direction and terminal relationships.
Where it sits
Common mistakes
Do not identify a wye solely by counting bushings. A neutral may remain inside the tank, and an external terminal may serve a purpose other than the assumed connection. Read the winding diagram and terminal labels together.
Missing or illegible diagrams justify checking manufacturer records rather than guessing.
Another mistake is claiming delta eliminates harmonics. A closed delta provides a circulating path for triplen harmonic currents, including the third harmonic; those currents can still heat windings.
Nonlinear 277-volt loads can produce triplen currents that add in a wye neutral rather than cancel like balanced fundamental currents.
On the ground
How it affects value
Connection affects reuse suitability, not just the description on a removal sheet. A documented delta-wye unit with an accessible secondary neutral can fit grounded four-wire service applications.
A unit with an unusual phase relationship, inaccessible neutral, or incomplete plate requires closer engineering review before another installation can be considered.
Grounding history also matters during assessment. A wye neutral can be solidly grounded, impedance grounded, or ungrounded; the winding connection alone does not establish which arrangement was used.
Records of neutral faults, overheated X0 connections, or damaged bushings help distinguish installation problems from possible winding damage requiring further testing.
Local reality
What to do next
Photograph the entire nameplate, then take close views of the voltage entries, connection diagram, kVA rating, and terminal designations. Record whether a neutral grounding resistor or grounding transformer belonged to the installation.
Keep the one-line diagram with the equipment record, particularly for units removed from North Carolina industrial substations.
Before opening a terminal compartment, have qualified electrical personnel isolate, verify absence of voltage, and apply protective grounds as required by the work procedure. Document accessible H1, H2, H3, X1, X2, X3, and X0 markings without disturbing connections.
Describe missing plates or uncertain connections explicitly rather than assigning a configuration.
Get started
Get an offer in minutes
Five fields is all it takes. Photographs help, but a nameplate and a town are enough to start.
No fee, no obligation. We reply the same business day.
Tell us what you have
We reply the same business day.
Questions
Straight answers
Equipment types
Does a wye connection always mean grounded neutral?
No. Wye describes the winding arrangement, while grounding describes how its common point connects to earth. An X0 terminal may be solidly grounded, connected through a resistor, or left ungrounded. Check the one-line diagram and physical neutral connections before describing the grounding method.
Service area
Can delta and wye transformers operate in parallel?
Not merely because their voltage and kVA ratings match. Parallel operation requires compatible phase displacement, polarity, voltage ratio, impedance, and phase sequence. A delta-wye transformer commonly has a 30-degree displacement that differs from a delta-delta unit.
Payment
What nameplate details identify delta and wye?
Look for a winding connection diagram, delta or wye symbols, terminal labels, and voltage notation such as 480Y/277. Some plates also show a vector group identifying winding connections and phase displacement.
Logistics
How it affects value: what should a seller know?
Connection affects reuse suitability, not just the description on a removal sheet. A documented delta-wye unit with an accessible secondary neutral can fit grounded four-wire service applications.