The 300 kVA substation transformer is built for primary distribution service, stepping medium- or high-voltage supply down to a distribution or utilization voltage. It is supplied with throat or bus connections for integration into a switchgear lineup. At 300 kVA it functions as a small unit substation for industrial plants and campus distribution.
Specifications
| Rating | 300 kVA |
|---|---|
| Phase | Three phase |
| Primary voltage class | 15kV / 25kV / 35kV |
| Secondary voltage class | 4160V / 480V / 12470V / 24940V |
| Basic insulation level (BIL) | 95 kV / 125 kV / 150 kV |
| Frequency | 60 Hz |
| Temperature rise | 65 °C |
| Winding material | Aluminum |
| Insulating fluid | Mineral oil, Type I |
| Cooling class | ONAN |
| Taps | Plus/minus 2 x 2.5% full-capacity below and above nominal |
| Enclosure | Munsell Green 7GY3.29/1.5, tamper-resistant |
| Feed configuration | Per application |
| Standards | ANSI/IEEE C57.12, NEMA, DOE 2016 efficiency |
| Lead time | As little as 10 weeks |
Available voltage configurations
The 300 kVA is offered in 44 primary and secondary voltage combinations. Price is set by voltage class, so every voltage within a class carries the same price – a 12470Y/7200 primary and a 13200Y/7620 primary are both 15 kV class and cost the same.
Primary voltages available:
- 15kV class — 2400 Delta, 4160 Delta, 4160Y/2400, 4800 Delta, 7200 Delta, 12000 Delta, 12470Y/7200, 13200 Delta, 13200Y/7620, 13800 Delta, 13800Y/7970
- 25kV class — 22900Y/13200, 24940Y/14400
- 35kV class — 34500 Delta, 34500Y/19920
Secondary voltages available:
- 4160V class — 4160Y/2400
- 480V class — 480Y/277
- 12470V class — 12470Y/7200, 13200Y/7620, 13800 Delta
- 24940V class — 24940Y/14400
Full-load current
Rated secondary current for a 300 kVA unit at each available secondary voltage. Use these figures for conductor, breaker and bus sizing.
| Secondary voltage | Full-load current |
|---|---|
| 4160Y/2400 | 42 A |
| 480Y/277 | 361 A |
| 12470Y/7200 | 14 A |
| 13200Y/7620 | 13 A |
| 13800 Delta | 13 A |
| 24940Y/14400 | 7 A |
Rated primary current at each available primary voltage:
| Primary voltage | Full-load current |
|---|---|
| 2400 Delta | 72 A |
| 4160 Delta | 42 A |
| 4160Y/2400 | 42 A |
| 4800 Delta | 36 A |
| 7200 Delta | 24 A |
| 12000 Delta | 14 A |
| 12470Y/7200 | 14 A |
| 13200 Delta | 13 A |
| 13200Y/7620 | 13 A |
| 13800 Delta | 13 A |
| 13800Y/7970 | 13 A |
| 22900Y/13200 | 7.6 A |
| 24940Y/14400 | 6.9 A |
| 34500 Delta | 5.0 A |
| 34500Y/19920 | 5.0 A |
Typical applications
- Industrial plant primary supply
- Campus and district distribution
- Small utility distribution substations
- Renewable collection systems
Construction
Standard construction is aluminum windings in a sealed tank with mineral oil, ONAN cooled, 65 °C rise. The tank is welded and finished in Munsell Green 7GY3.29/1.5. A four-position no-load tap changer provides plus and minus two 2.5% full-capacity taps. Copper windings and natural ester fluid, including STRATA X3, are available on request.
Standards and compliance
- Built to ANSI/IEEE C57.12 and applicable NEMA standards
- Meets DOE 2016 efficiency requirements
- Factory test report supplied with every unit
- Manufactured and supported by Bear Power Solutions, Brandon, Mississippi
Frequently asked questions
What voltages is the 300 kVA available in?
The 300 kVA is available with 15kV / 25kV / 35kV primary and 4160V / 480V / 12470V / 24940V secondary. That is 44 configurations in total. Every voltage inside a class carries the same price and the same basic insulation level.
What is the lead time on a 300 kVA?
Lead times start at 10 weeks from order confirmation, depending on configuration and current factory loading. Non-standard voltages, accessories, custom enclosure work and non-standard fluid or winding material extend that. Confirm the delivery date with Bear Power Solutions before committing to a project schedule.
Can this be supplied with a switchgear throat connection?
Yes. Substation transformers are commonly supplied with primary and secondary throat or bus connections for direct integration into a switchgear lineup. Specify the mating arrangement at time of quotation.
Can the 300 kVA be supplied with copper windings or natural ester fluid?
Standard catalog construction is aluminum windings with mineral oil. Copper windings and natural ester fluid – including STRATA X3, Bear Power Solutions’ own Type II natural ester – are available on request. Both affect price and lead time, so request a quotation for a non-standard build.
What standards does the 300 kVA meet?
Units are built to ANSI/IEEE C57.12 and applicable NEMA standards, and meet DOE 2016 efficiency requirements. Factory test reports are provided with every unit.
Sizing the 300 kVA
At its lowest available secondary voltage the 300 kVA draws 361 A at full load; at its highest it draws 7 A. That spread is what makes secondary voltage selection an installation-cost decision as much as an electrical one – the higher voltage cuts conductor size for the same delivered power.
Secondary current at this rating is generally within the range of single conductor runs per phase, which keeps termination and cable costs down.
Choosing between 300 kVA and adjacent ratings
Bear Power Solutions also builds the 500 kVA above it in this family. If your calculated connected load sits within about 20 percent of the 300 kVA rating, the 500 kVA is usually the better specification – transformers run most efficiently loaded well below nameplate, and the headroom costs less now than a replacement does later. Request a quote below with your actual load data and Bear Power Solutions will recommend a rating.
Request a quote
For a firm price on a 300 kVA in a specific voltage configuration, or for a non-standard build with copper windings, natural ester fluid or custom accessories, send the details below and Bear Power Solutions will respond with a written quotation.
