A 100 kVA single-phase transformer can serve a larger home, a light commercial building or one position in a three-transformer bank. The rating alone does not identify its application. We pay attention to the primary voltage, secondary voltage, bushing arrangement and whether the unit is pole-mounted or housed in a ground-level cabinet.
We buy this size across Virginia, whether you have one retired unit or several surplus transformers. Our transformer size guide covers other ratings, but this page focuses on what makes a 100 kVA single-phase unit identifiable and useful to a buyer.
01What the 100 kVA Rating Actually Means
The 100 kVA nameplate rating describes apparent-power capacity under the transformer's specified operating conditions. It is not a promise of 100 kW of usable load in every application. Real power depends on load power factor, while allowable loading also depends on the equipment's design and operating conditions.
For single-phase equipment, full-load current is calculated as kVA × 1,000 ÷ voltage. At a 240-volt secondary, a worked example is 100 × 1,000 ÷ 240 = approximately 416.7 amps. Use the amp table on this page for other voltages, and see the kVA and full-load amps guide for the distinction between single-phase and three-phase calculations.
02Pole-Mount and Pad-Mount Forms at 100 kVA
A 100 kVA pole-mount transformer typically has a tank with mounting brackets and externally accessible bushings. One or two high-voltage bushings may be present, depending on the winding and grounding arrangement. Photographs of the top, sides and mounting hardware help distinguish configurations that share the same rating.
A single-phase pad-mount transformer encloses its connections in a cabinet designed for ground-level installation. Dead-front and live-front arrangements differ, and loop-feed versus radial-feed construction affects the primary connection layout. We buy both pole-mount transformers and single-phase pad-mount units; photograph accessible exterior details without entering energized compartments.
Full-load amps for a 100 kVA single-phase transformer
The amp table on this page uses the standard formula Amps = kVA × 1,000 ÷ volts. Match the voltage on your nameplate to read the rated full-load current of each winding.
| Winding voltage | Full-load amps |
|---|---|
| 120 V | 833 |
| 240 V | 417 |
| 480 V | 208 |
| 2,400 V | 41.7 |
| 7,200 V | 13.9 |
| 7,620 V | 13.1 |
| 7,970 V | 12.5 |
| 14,400 V | 6.9 |
| 19,920 V | 5 |
03Voltage Combinations That Identify the Application
A 120/240-volt secondary is common on 100 kVA single-phase distribution transformers serving larger residential or light commercial loads. Primary ratings may include 7200 volts or a marking such as 12470GrdY/7200. The latter identifies use on a grounded-wye system with 12,470 volts line to line and 7,200 volts line to neutral; it does not make the transformer three-phase.
Other primary ratings include 7620, 13200 or 14400 volts, depending on the distribution system and winding design. Units with 240/480-volt secondaries also exist. Send the exact markings, including slashes, grounding notation and tap information, rather than describing the unit as simply 'high voltage to low voltage.' Similar-looking tanks can have very different electrical applications.
04Confirm 100 kVA and Single Phase on the Nameplate
Look for a nameplate that explicitly states 100 kVA and identifies the phase as single-phase, 1 PH or an equivalent designation. Do not rely only on a painted tank number or inventory tag. A straight-on photograph should capture the whole plate, with a second close-up if stamped characters are faint.
We use the plate to separate the capacity rating from voltage, temperature-rise and identification information. On older units, a faded plate may still reveal useful winding or serial-number details. Include any available records that match the serial number, especially fluid documentation and test reports, without attempting new electrical tests yourself.
- Manufacturer, model and serial number
- 100 kVA rating, phase and frequency
- Primary voltage, secondary voltage and tap positions
- Impedance and temperature-rise information, when listed
- Total weight, fluid type and fluid quantity, when listed
05Physical Size, Weight and Loading Details
There is no single standard footprint or weight for every 100 kVA transformer. Tank design, conductor material, fluid volume, cooling surfaces and cabinet construction all affect handling. A pad-mount cabinet also needs space around it for access, while a pole-mount unit may have brackets or bushings extending beyond the tank dimensions.
Send the nameplate weight when available and approximate overall dimensions, including projecting components. Describe whether the transformer is still installed, sitting on a pallet or stored directly on the ground. Clear photos of lifting provisions, the base and the surrounding access area help establish practical freight and loading terms. Do not drain fluid to reduce shipping weight.
06What Drives Interest in a 100 kVA Unit
The 100 kVA rating fits applications needing more capacity than a 50 kVA single-phase transformer, without stepping up to a 167 kVA single-phase unit. Actual suitability depends on the load and system design. Buyer interest depends on matching voltage, connection arrangement, condition and documentation, not capacity alone.
Three 100 kVA single-phase transformers can form a nominal 300 kVA three-phase bank when properly matched and connected in a suitable configuration. If your units came from a bank, identify each unit and include all three nameplates. Matching ratings do not prove matching impedance, polarity or suitability for reuse together; those details require qualified technical review.
07What We Need for a Written Purchase Offer
To sell 100 kVA single-phase transformer equipment, give us its actual condition rather than just 'used.' Note leaks, missing bushings, damaged cabinet doors, corrosion or a known electrical failure. Identify mineral oil or FR3 natural ester if documented. PCB status must be disclosed and documented; age, appearance and fluid color are not substitutes for records.
Send clear nameplate and overall photos, location, quantity and condition notes through the offer form. We review the information and may ask about PCB status, test data or site access. If the equipment fits, our written offer specifies price, freight, loading and payment terms; pickup is scheduled with you and payment follows those terms. See how the purchase process works for details.
Frequently asked questions
Is a 100 kVA transformer with three secondary bushings single-phase?
Yes, a 100 kVA transformer can be single-phase with three secondary bushings. A center-tapped 120/240-volt secondary commonly has two outer terminals and a neutral terminal. Bushing count alone does not establish phase. Send the nameplate and visible terminal markings so we can identify the listed configuration without guessing from appearance.
Can I sell one 100 kVA transformer from a three-unit bank?
Yes, we buy individual 100 kVA single-phase transformers as well as groups of units. Tell us that the transformer came from a bank and provide its own nameplate photo. If the other units are also available, photograph each plate separately because their voltage ratings, impedance or other details may differ.
Do you buy older 100 kVA pole transformers with unreadable nameplates?
We buy older 100 kVA pole-mount transformers, but an unreadable nameplate can limit identification and an offer. Send close-up photos, any readable serial number and matching inventory or maintenance records. Do not scrape, dismantle or disturb equipment to uncover information. PCB status must still be disclosed and documented.
Can I sell a 100 kVA pad-mount transformer that has leaked oil?
Failed or damaged 100 kVA pad-mount transformers, including units with leaks, are reviewed case by case. Describe the leak and send photos taken from a safe position, along with available fluid and PCB documentation. We do not ask sellers to drain fluid or provide environmental advice; involve your qualified service providers as needed.
Does a 100 kVA transformer need to be disconnected before pickup?
An installed 100 kVA transformer must be safely de-energized and disconnected by your qualified electricians before it can be picked up. We do not perform electrical disconnect work. Tell us whether the unit remains connected, is removed from its pole or pad, or is already in storage so the written terms reflect its status.
Is Virginia Transformer Buyers the manufacturer of my 100 kVA transformer?
No, Virginia Transformer Buyers is an independent buyer, not a transformer manufacturer or an affiliate of Virginia Transformer Corp of Roanoke. We buy all brands of 100 kVA single-phase transformers. The manufacturer name on your plate helps identify the equipment; it does not indicate any affiliation with our business.