Comprehensive specifications for 300.0 kVA dead-front padmount transformer including dimensions, weight, concrete pad requirements, and electrical data
Quick Specifications
| Rated Power: | 300.0 kVA | Phase: | Three-Phase |
| Primary Voltage: | 12470GY/7200 | Secondary Voltage: | 208Y/120 |
| Enclosure: | Dead-Front | Cooling: | ONAN |
| Weight: | 3100 lbs (1406 kg) | Concrete Pad: | 84″ × 84″ |
| Dimensions (H×W×D): | 44″ × 66″ × 52″ (1118 × 1676 × 1321 mm) | ||
A 300.0 kVA padmount transformer is a ground-mounted, oil-filled distribution transformer commonly used in manufacturing facilities, large campuses. This guide provides complete specifications for utility engineers, electrical contractors, and facility planners.
300.0 kVA Padmount Transformer Dimensions
| Dimension | Metric (mm) | Imperial (inches) |
|---|---|---|
| Height (H) | 1118 mm | 44″ |
| Width (W) | 1676 mm | 66″ |
| Depth (D) | 1321 mm | 52″ |
Concrete Pad Requirements
The 300.0 kVA padmount transformer requires a properly designed concrete pad for installation:
| Pad Specification | Requirement | Notes |
|---|---|---|
| Minimum Pad Size | 84″ × 84″ | Allow 6″ overhang on all sides |
| Pad Thickness | 4-6 inches | Reinforced concrete, 3000 PSI minimum |
| Grade/Slope | Level ± 1/4″/ft | Slight slope away from buildings |
| Conduit Entry | Per utility specs | Primary and secondary duct banks |
| Curing Time | 28 days minimum | Before transformer placement |
Weight and Oil Specifications
| Specification | Value | Notes |
|---|---|---|
| Total Weight (with oil) | 3100 lbs (1406 kg) | Includes all oil and accessories |
| Oil Volume | 156 gallons (590 L) | Mineral insulating oil |
| Cooling Class | ONAN | Oil Natural, Air Natural |
| BIL Rating | 125 kV | Basic Insulation Level |
Electrical Specifications
| Parameter | Value | Notes |
|---|---|---|
| Rated kVA | 300.0 kVA | At rated voltage and ONAN cooling |
| Primary Voltage | 12470GY/7200 | With taps ±2.5%, ±5% |
| Secondary Voltage | 208Y/120 | Standard service voltage |
| No-Load Loss | 560 W | Core losses |
| Load Loss | 2350 W | At rated load |
| Total Losses | 2910 W | At 100% load |
| Impedance | 4.75% | Per IEEE C57.12.00 |
| Efficiency | 99.1% | DOE 2016 compliant |
Secondary Full Load Amps
Full load amperage at secondary voltage for 300.0 kVA three-phase padmount transformer:
| Secondary Voltage | Full Load Amps | Conductor Size |
|---|---|---|
| 120V | 1443.4 A | 750+ MCM |
| 208V | 832.7 A | 750+ MCM |
| 240V | 721.7 A | 750+ MCM |
| 277V | 625.3 A | 750+ MCM |
| 480V | 360.9 A | 500 MCM |
Three-Phase:
Amps = (kVA × 1000) ÷ (Voltage × √3)Example at 240V:
721.7 A = (300.0 × 1000) ÷ (240 × 1.732)When to Choose a 300.0 kVA Padmount Transformer
The 300.0 kVA three-phase padmount suits large commercial buildings, manufacturing facilities, and campus distribution requiring substantial load capacity.
Typical Load Distribution for 300.0 kVA Padmount Transformer
| Load Type | Estimated Demand |
|---|---|
| Industrial motors | 135 kVA |
| Process equipment | 90 kVA |
| Building services | 45 kVA |
Note: Load estimates are typical values. Consult project load study for specific applications.
Related Padmount Transformer Sizes
Compare with adjacent kVA ratings:
| kVA Rating | Link |
|---|---|
| 225.0 kVA Three-Phase | 225.0 kVA Padmount Specs → |
| 300.0 kVA Three-Phase | Current Page |
| 500.0 kVA Three-Phase | 500.0 kVA Padmount Specs → |
Frequently Asked Questions
What size concrete pad do I need for a 300.0 kVA padmount transformer?
A 300.0 kVA padmount transformer requires a minimum pad size of 84″ × 84″ with 4-6 inches thickness of reinforced concrete.
How much does a 300.0 kVA padmount transformer weigh?
A 300.0 kVA padmount transformer weighs approximately 3100 lbs (1406 kg) including oil.
What is the difference between dead-front and live-front padmount transformers?
Dead-front designs (like this 300.0 kVA unit) have all connections inside the locked cabinet with no exposed live parts. Live-front designs have bushings exposed on top, requiring additional safety barriers in public areas.
Related Resources
📊 Padmount Reference Charts:
- Padmount Transformer Sizing Chart – Compare all kVA ratings with pad sizes
- Padmount Full Load Amps Chart – FLA reference for all voltages
Related Articles
- Pad Mounted Transformer: Complete Guide
- Transformer Oil: Complete Guide
- Transformer Protection: Complete Guide
Standards & References
- IEEE C57.12.28 – Pad-Mounted Equipment Enclosure Integrity
- IEEE C57.12.34 – Requirements for Pad-Mounted Transformers
- IEEE C57.12.26 – General Requirements for Padmounted Equipment
- DOE 10 CFR 431 – Energy Conservation Standards for Transformers
- NEC Article 450 – Transformer Installation Requirements
Disclaimer: Specifications shown are typical reference values compliant with IEEE and DOE standards. Actual specifications vary by manufacturer and specific configuration. Always consult manufacturer datasheets and local utility requirements. Last updated: January 2026