Comprehensive specifications for 75 kVA ONAN oil-filled transformer including dimensions, weight, oil volume, and electrical data
Quick Specifications
| Rated Power: | 75 kVA | Phase: | Three-Phase |
| Primary Voltage: | 12470Y/7200V | Secondary Voltage: | 208Y/120V |
| Cooling Class: | ONAN | BIL Rating: | 95 kV |
| Weight: | 1250 lbs (567 kg) | Oil Volume: | 50 gallons (189 L) |
| Dimensions (H×W×D): | 46″ × 35″ × 26″ (1180 × 880 × 670 mm) | ||
A 75 kVA oil-filled transformer is commonly used for Large commercial, light industrial. This guide provides complete specifications for utility engineers, electrical contractors, and procurement professionals.
75 kVA Oil-Filled Transformer Dimensions
| Dimension | Metric (mm) | Imperial (inches) |
|---|---|---|
| Height (H) | 1180 mm | 46″ |
| Width (W) | 880 mm | 35″ |
| Depth (D) | 670 mm | 26″ |
🔧 Installation Note: This 75 kVA oil-filled transformer weighs 1250 lbs and contains 50 gallons of insulating oil. Required:
- Concrete pad rated for 1875 lbs minimum
- Oil containment per EPA SPCC requirements (110% capacity)
- Minimum 10ft clearance from buildings for outdoor installation
- 4-8 hour settling time before energizing
Weight and Oil Specifications
| Specification | Value | Notes |
|---|---|---|
| Total Weight (with oil) | 1250 lbs (567 kg) | Includes all oil and accessories |
| Oil Volume | 50 gallons (189 L) | Mineral Oil |
| Oil Type | Mineral Oil | IEEE C57.106 compliant |
| Containment Required | 55 gallons | 110% per EPA SPCC |
Electrical Specifications
| Parameter | Value | Notes |
|---|---|---|
| Rated kVA | 75 kVA | At rated voltage and ONAN cooling |
| Primary Voltage | 12470Y/7200V | Standard utility distribution voltage |
| Secondary Voltage | 208Y/120V | Service voltage |
| Cooling Class | ONAN | Oil Natural, Air Natural |
| BIL Rating | 95 kV | Standard for 12.47kV-15kV primary |
| No-Load Loss | 200 W | Core losses |
| Load Loss | 800 W | At rated load |
| Total Losses | 1000 W | At 100% load |
| Impedance | 4.5% | Per IEEE C57.12.00 |
| Efficiency | 98.7% | At rated load |
| Sound Level | ~46 dB | Per NEMA TR-1 |
Secondary Full Load Amps
Full load amperage at secondary voltage for 75 kVA three-phase transformer:
| Secondary Voltage | Full Load Amps | Conductor Size |
|---|---|---|
| 120V | 360.9 A | 500 MCM |
| 208V | 208.2 A | 250 MCM |
| 240V | 180.4 A | 4/0 AWG |
| 277V | 156.3 A | 3/0 AWG |
| 480V | 90.2 A | #2 AWG |
Three-Phase:
Amps = (kVA × 1000) ÷ (Voltage × 1.732)Example at 480V:
90.2 A = (75 × 1000) ÷ (480 × 1.732)Oil Maintenance Guidelines for 75 kVA Transformer
Proper maintenance of the 50 gallons of Mineral Oil in this transformer is critical for long-term reliability:
| Maintenance Task | Frequency | Purpose |
|---|---|---|
| Visual Oil Level Check | Monthly | Detect leaks, ensure adequate level |
| Oil Sample Analysis | Annually | Dielectric strength, dissolved gas analysis (DGA) |
| Oil Filtration/Reconditioning | Every 3-5 years | Remove moisture and contaminants |
| Silica Gel Breather Check | Quarterly | Ensure moisture protection |
| Bushing Inspection | Annually | Check for cracks, contamination, oil leaks |
⚠️ Oil Handling Safety:
- Always use proper PPE when handling transformer oil
- Dispose of contaminated oil according to EPA regulations
- Never mix different oil types without compatibility testing
- Maintain SPCC containment at all times
When to Choose a 75 kVA Three-Phase Oil-Filled Transformer
A 75 kVA three-phase oil-filled transformer is well-suited for:
- Commercial building service entrance
- Small manufacturing facilities
- Utility distribution substations
- Shopping centers and retail developments
- Medium-voltage industrial applications
Cooling Class ONAN: 自然油循环、自然空气冷却
Typical Load Distribution for 75 kVA Oil-Filled Transformer
Example utility distribution loads for a 75 kVA oil-filled transformer:
| Load Type | Estimated Demand |
|---|---|
| Three-phase motor loads | 30 kVA |
| HVAC systems | 18 kVA |
| Lighting transformers | 11 kVA |
| Receptacle/misc loads | 15 kVA |
Note: Utility distribution varies by application. Consult with utility engineer for specific load allocations.
Related Oil-Filled Transformer Sizes
Compare with adjacent kVA ratings:
| kVA Rating | Link |
|---|---|
| 45 kVA Three-Phase | 45 kVA Oil-Filled Specs → |
| 75 kVA Three-Phase | Current Page |
| 112.5 kVA Three-Phase | 112.5 kVA Oil-Filled Specs → |
Frequently Asked Questions
How much oil does a 75 kVA oil-filled transformer contain?
A 75 kVA three-phase oil-filled transformer typically contains 50 gallons (189 liters) of Mineral Oil insulating oil.
What are the dimensions of a 75 kVA oil-filled transformer?
Typical dimensions are 46″ H × 35″ W × 26″ D (1180 × 880 × 670 mm).
How much does a 75 kVA oil-filled transformer weigh?
A 75 kVA oil-filled transformer weighs approximately 1250 lbs (567 kg) including oil.
What is the BIL rating for a 75 kVA transformer?
The standard BIL (Basic Insulation Level) rating is 95 kV, which is standard for 12.47kv-15kv primary.
Related Resources
📊 Complete Reference Charts:
- Transformer Sizing Chart – Compare all kVA ratings
- Transformer Full Load Amps Chart – FLA reference for all voltages
Related Articles
- Transformer Oil: Complete Guide to Types, Testing & Maintenance
- Three Phase Transformer: Complete Guide
- Transformer Protection: Complete Guide
Standards & References
- IEEE C57.12.00 – General Requirements for Liquid-Immersed Distribution Transformers
- IEEE C57.12.90 – Test Code for Liquid-Immersed Distribution Transformers
- IEEE C57.106 – Guide for Acceptance and Maintenance of Insulating Oil
- NEMA TR-1 – Transformers, Regulators and Reactors
- EPA 40 CFR 112 – SPCC Requirements
Disclaimer: Specifications shown are typical reference values. Actual specifications vary by manufacturer, voltage class, and application. Oil-filled transformers require proper containment, maintenance, and environmental compliance. Always consult manufacturer datasheets and local codes. Last updated: January 2026