What we buy
Ranges we buy on this page
This guide covers off-load and on-load tap changers, the usual plus and minus five percent range, and failures involving contacts, selectors, and operating mechanisms.
The nameplate tap table, present handle position, and maintenance records help distinguish an ordinary voltage adjustment from damaged switching equipment.
| Phase | kVA | Voltage | Fluid |
|---|---|---|---|
| 1-phase | 10 - 333 kVA | up to 25 kV | Liquid or dry |
| 3-phase | 25 - 10,000 kVA | 25 kV | Liquid-filled |
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
The short version
A tap changer selects connection points on a winding to change the transformer ratio. Many distribution transformers have five primary tap positions covering plus and minus five percent in 2.5 percent steps.
The nameplate governs; neither the handle markings nor the cabinet shape proves that arrangement.
An off-load tap changer, also called a de-energized tap changer, must not be operated while the transformer is energized. An on-load tap changer changes ratio under load using a controlled switching sequence.
Its selector, diverter arrangement, drive mechanism, and controls require their own inspection and maintenance.
Local reality
Why a seller should care
For an owner retiring a 13,200-volt transformer in North Carolina, the tap table helps explain the equipment's intended service. Photograph every nameplate line and the external position indicator.
A buyer needs to know whether the installed ratio matches the plate or reflects a later winding modification.
A failed tap mechanism does not automatically establish that the core and windings are damaged. Conversely, a handle that moves freely does not prove sound internal contacts.
Inspection reports, winding resistance results, and transformer turns ratio test records help separate a localized switching defect from broader electrical damage.
Around the site
The arithmetic
For a nominal 13,200-volt primary, a five-position tap table might read 13,860, 13,530, 13,200, 12,870, and 12,540 volts. Those values represent plus five, plus 2.5, nominal, minus 2.5, and minus five percent.
Confirm the actual sequence on the nameplate before interpreting any numbered handle position or test result.
With 13,200 volts applied, selecting a primary tap rated 13,860 volts lowers secondary voltage: 480 multiplied by 13,200 divided by 13,860 is about 457 volts. Selecting the 12,540-volt tap raises it to about 505 volts.
This simplified calculation assumes a nominal 480-volt secondary and neglects load-related voltage drop.
Where it sits
Where people go wrong
The most dangerous mistake is treating an off-load handle like an operating switch. A qualified crew must isolate all sources, address possible secondary backfeed, verify absence of voltage, and follow required grounding procedures before changing taps.
Opening a primary device alone does not establish a safe work condition.
Poor contact pressure, misalignment, or incomplete engagement can produce localized heating at a de-energized tap selector. On-load equipment can suffer contact erosion, carbon deposits, drive faults, or transition-component failures.
Burned oil and abnormal gas results need investigation, with samples identified by the main tank or separate tap-changer compartment.
On the ground
Value impact
Tap condition affects whether a retired transformer can be evaluated for reuse, repair, or material recovery. A complete tap table and documented position reduce uncertainty about its ratio.
Missing selector parts, burned connections, or an inaccessible mechanism can limit evaluation even when the tank and bushings appear intact.
For on-load equipment, include the drive cabinet, control diagrams, operation counter reading, and maintenance history in the equipment description. Note whether the diverter compartment has separate oil.
Transformer Buyers NC buys used, surplus, failed, and obsolete transformers across North Carolina, including units with documented tap-changer defects.
Local reality
Your next move
Start with photographs of the nameplate, tap diagram, position indicator, and any external drive cabinet. Record the last operating position without moving the mechanism merely for a photograph.
For a unit already disconnected, provide the isolation status and any report describing why it was removed from service.
Before pickup planning, identify loose control cabinets, removed covers, leaking gaskets, and separate oil compartments. Give the removal crew the transformer dimensions, weight, and access restrictions, including clearance around the tap-changer housing.
Preserve test sheets and maintenance logs with the unit rather than leaving them in the switchgear room.
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
Can an off-load tap changer operate while energized?
No. An off-load or de-energized tap changer is not designed to interrupt energized circuits. A qualified crew must establish electrical isolation, check for backfeed, verify absence of voltage, and follow grounding requirements before operating it. Follow the manufacturer's procedure for engagement and position verification.
Service area
Does a plus five percent tap raise secondary voltage?
Not necessarily; interpret the nameplate voltage table rather than the sign alone. On a primary tap rated five percent above nominal, unchanged incoming voltage generally produces lower secondary voltage. For a 13,200-to-480-volt unit, the 13,860-volt primary tap produces approximately 457 volts at nominal input.
Payment
What records help document a failed tap changer?
Provide the tap table, recorded position, failure report, and available turns ratio and winding resistance results. For on-load equipment, include operation counts, control alarms, and oil test records labeled by compartment.
Logistics
Value impact: what should a seller know?
Tap condition affects whether a retired transformer can be evaluated for reuse, repair, or material recovery. A complete tap table and documented position reduce uncertainty about its ratio.