Transformers & Substations
225 kVA three-phase pad-mounted transformer
271 A at 480 V · 625 A at 208 V · 15 / 25 / 35 kV class
Overview
A 225 kVA three-phase pad-mounted transformer is a liquid-filled, dead-front distribution transformer for ground-level medium-voltage service: a 12.47 / 13.2 / 13.8 kV (15 kV class), 24.94 kV (25 kV class) or 34.5 kV (35 kV class) primary stepping down to 208Y/120, 480Y/277 or 600Y/347 V at 60 Hz. At full load it delivers 271 A at 480 V, 625 A at 208 V or 217 A at 600 V, and draws 10.4 A from a 12.47 kV feeder. Entogo designs and builds the 225 kVA unit to IEEE C57.12.34 / C57.12.28 and DOE 10 CFR 431 in its own factory, ships engineered-to-order units in 16–24 weeks, and offers UL (cULus) / CSA certification on request.
Full-load and primary current
Three-phase line current at rated load: amperes = kVA × 1000 ÷ (√3 × V).
| Winding / voltage | Full-load current |
|---|---|
| Secondary 208Y/120 V | 625 A |
| Secondary 480Y/277 V | 271 A |
| Secondary 600Y/347 V | 217 A |
| Primary 12.47 kV (15 kV class, 95 kV BIL) | 10.4 A |
| Primary 13.2 kV (15 kV class, 95 kV BIL) | 9.8 A |
| Primary 13.8 kV (15 kV class, 95 kV BIL) | 9.4 A |
| Primary 24.94 kV (25 kV class, 125 kV BIL) | 5.2 A |
| Primary 34.5 kV (35 kV class, 150 kV BIL) | 3.8 A |
Available secondary fault current
Three-phase bolted fault at the secondary terminals with an infinite primary source: full-load amps ÷ (%Z ÷ 100). Impedance is a specifier's choice; 5.75 % is common for larger pad-mounted units, lower values below about 500 kVA. Real values are lower once the utility source impedance is included.
| Impedance | 208Y/120 V | 480Y/277 V | 600Y/347 V |
|---|---|---|---|
| 4.00 % | 15.6 kA | 6.8 kA | 5.4 kA |
| 5.00 % | 12.5 kA | 5.4 kA | 4.3 kA |
| 5.75 % | 10.9 kA | 4.7 kA | 3.8 kA |
What a 225 kVA unit typically serves
- Mid-size commercial buildings, schools and clinics
- Multifamily and mixed-use developments
- Light industrial and warehouse service
- Level 2 charging hubs of roughly 10 to 30 ports
Typical, not prescriptive: size from the calculated load and growth margin — see how to size a transformer (kVA selection), and for EV-charging sites the service-capacity calculator.
Custom-engineered · built to order
Lead time
16–24 weeks
Order now for estimated delivery Jan 2027 – Mar 2027.
Certification / testing may extend this per the standard and scope.
FAQ
Common questions
- How many amps is a 225 kVA transformer at 480 V?
- A 225 kVA three-phase transformer delivers 271 A at 480 V full load (kVA × 1000 ÷ (√3 × 480)). At 208 V the same unit delivers 625 A and at 600 V 217 A.
- What is the primary current of a 225 kVA pad-mounted transformer?
- On a 12.47 kV feeder a 225 kVA unit draws 10.4 A at full load; on 13.8 kV 9.4 A, on 24.94 kV 5.2 A and on 34.5 kV 3.8 A.
- How much fault current can a 225 kVA transformer deliver?
- With an infinite primary source, a 225 kVA unit at 480 V and 5.75 % impedance can deliver about 4.7 kA of three-phase bolted-fault current (full-load amps ÷ 0.0575). The real value is lower once the utility's source impedance is included; the switchgear downstream must be rated for the study value, not this ceiling.
- How long does a 225 kVA pad-mounted transformer take to deliver from Entogo?
- 225 kVA pad-mounted units are engineered to order and ship from Entogo's own factory in 16–24 weeks. If the order needs new UL (cULus) or CSA certification, delivery is guaranteed within 36 weeks — against the one-to-four-year lead times common in the North-American merchant market.
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