Transformers & Substations
75 kVA three-phase pad-mounted transformer
90.2 A at 480 V · 208 A at 208 V · 15 / 25 / 35 kV class
Overview
A 75 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 90.2 A at 480 V, 208 A at 208 V or 72.2 A at 600 V, and draws 3.5 A from a 12.47 kV feeder. Entogo designs and builds the 75 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 | 208 A |
| Secondary 480Y/277 V | 90.2 A |
| Secondary 600Y/347 V | 72.2 A |
| Primary 12.47 kV (15 kV class, 95 kV BIL) | 3.5 A |
| Primary 13.2 kV (15 kV class, 95 kV BIL) | 3.3 A |
| Primary 13.8 kV (15 kV class, 95 kV BIL) | 3.1 A |
| Primary 24.94 kV (25 kV class, 125 kV BIL) | 1.7 A |
| Primary 34.5 kV (35 kV class, 150 kV BIL) | 1.3 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 % | 5.2 kA | 2.3 kA | 1.8 kA |
| 5.00 % | 4.2 kA | 1.8 kA | 1.4 kA |
| 5.75 % | 3.6 kA | 1.6 kA | 1.3 kA |
What a 75 kVA unit typically serves
- Small commercial buildings and retail pads
- Underground residential subdivisions (URD loops)
- Workplace and multifamily Level 2 EV-charging hubs
- Telecom, water and utility auxiliary sites
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 75 kVA transformer at 480 V?
- A 75 kVA three-phase transformer delivers 90.2 A at 480 V full load (kVA × 1000 ÷ (√3 × 480)). At 208 V the same unit delivers 208 A and at 600 V 72.2 A.
- What is the primary current of a 75 kVA pad-mounted transformer?
- On a 12.47 kV feeder a 75 kVA unit draws 3.5 A at full load; on 13.8 kV 3.1 A, on 24.94 kV 1.7 A and on 34.5 kV 1.3 A.
- How much fault current can a 75 kVA transformer deliver?
- With an infinite primary source, a 75 kVA unit at 480 V and 5.75 % impedance can deliver about 1.6 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 75 kVA pad-mounted transformer take to deliver from Entogo?
- 75 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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