Three-Phase Padmount Transformer
Tamper-resistant three-phase padmount transformers for underground commercial and industrial distribution systems. Available from 15 kVA to 2,500 kVA at primary voltages from 5 kV to 34.5 kV.
Three-Phase Underground Distribution
Three-phase padmount transformers serve as the final voltage conversion stage in underground distribution systems, stepping medium-voltage utility power down to the utilization voltage required by commercial buildings, industrial facilities, and large residential developments. Their locked, tamper-resistant enclosures meet public-access installation requirements.
- Liquid-filled ONAN cooling for maximum thermal efficiency
- Compartmentalized design with separate HV and LV sections
- Radial or loop-feed high-voltage configuration
- Custom secondary voltage and winding arrangements
- Integral overcurrent protection options (fused or non-fused)
- Tank-mounted arresters, pressure relief, and ground provisions
What's Included
- NEMA 3R-equivalent tamper-resistant enclosure
- Separate lockable HV and LV compartments
- Mineral oil or FR3 natural ester fluid options
- Copper or aluminum winding conductor
- Standard 2.5% FCAN and 5.0% FCBN voltage taps
- Welded tank with pressure relief device
- Stainless steel hardware and locking bars
- Ground boss provision on tank
- +FR3 natural ester fluid (fire-safe, biodegradable)
- +Stainless steel enclosure for coastal environments
- +Bay-O-Net fuses with built-in expulsion element
- +S&C T-Link, ABB loadbuster, or equivalent HV protection
- +Automatic sectionalizing switch (loop feed)
- +SCADA-compatible monitoring accessories
- +Custom paint colour and nameplate requirements
- +Thermal imaging port for predictive maintenance
Full Specifications
| Parameter | Value |
|---|---|
| kVA Range | 15 kVA – 2,500 kVA |
| Primary Voltage (HV) | 5 kV – 34.5 kV |
| Secondary Voltage (LV) | 208 V – 15 kV (custom available) |
| Winding Configuration | Three-phase, 2- or 3-winding |
| Cooling Class | ONAN (natural oil / natural air) |
| Insulating Fluid | Mineral oil or FR3 natural ester |
| Winding Material | Copper (standard) / Aluminum (option) |
| HV Taps | 2 × 2.5% FCAN, 2 × 2.5% FCBN |
| Temperature Rise | 65°C (standard) |
| Enclosure | Tamper-resistant, painted steel |
| Primary Standard | ANSI C57.12.26 / IEEE C57.12.00 |
| Canadian Certification | CSA C88 / CSA C22.2 |
| Frequency | 60 Hz |
Built to Standard
Where It's Used
- Commercial building complexes (underground service entry)
- Industrial plant distribution substations
- Solar and wind farm interconnection points
- Shopping centres and retail developments
- Data centre utility feed points
- Multi-unit residential developments
- Campus distribution networks (hospitals, universities)
- Transit facilities and EV charging infrastructure
From design and specification through factory testing, commissioning, and ongoing maintenance — Candron delivers at every phase.
- Engineering drawings and coordination studies
- Factory acceptance testing (FAT) with full reports
- Site commissioning and protection settings
- Spare parts, training, and maintenance support
Common Questions
A radial-feed padmount has a single HV cable connection in and is protected by a fuse. A loop-feed configuration has two HV cable connections — one in and one out — allowing the distribution loop to continue past the transformer. Loop feed provides redundancy and is standard for commercial underground distribution systems.
Yes. FR3 natural ester fluid is available as an upgrade and is recommended for installations near water bodies, in environmentally sensitive areas, or where fire-safe fluid is required. FR3 transformers are self-certified as less-flammable fluid-filled equipment under most electrical codes.
Padmount transformers can be supplied with conventional expulsion fuses, current-limiting fuses, Bay-O-Net fuses with partial range current-limiting elements, or fully coordinated HV protection schemes including vacuum fault interrupters (VFI) for loop-feed applications.
Standard taps are 2 × 2.5% FCAN (full capacity above nominal) and 2 × 2.5% FCBN (full capacity below nominal) on the HV winding. Custom tap positions and expanded tap ranges can be specified for applications with wide primary voltage variation.
Ready to Spec
Your Project?
Our engineering team responds with specs, lead times, and pricing the same day. Tell us what you need:
- Required kVA rating
- Primary voltage (HV) and system grounding
- Secondary voltage (LV) and connection type
- Radial or loop-feed HV configuration
- Required overcurrent protection type
- Fluid preference (mineral oil or FR3)
- Site location and environmental conditions
- Applicable standards (ANSI or CSA)
Send us your project details and we'll respond with a price, lead time, and any clarifying questions — typically within a few hours.
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