What Is a 315 kVA Mini Substation?
A 315 kVA mini substation (also known as compact substation or package substation) is a prefabricated power distribution unit that integrates a transformer, high-voltage switchgear, low-voltage switchgear, protection devices, and internal wiring into a single outdoor enclosure. It is designed to step down medium voltage (typically 11kV or 33kV) to a low-voltage level (400V) suitable for local distribution.
These units are widely used in urban networks, industrial zones, commercial areas, and temporary construction projects, where space and installation time are limited.
Key Components of 315 kVA Compact Substation
A typical mini substation includes:
- HV Section: Load break switch (LBS) or vacuum circuit breaker (VCB)
- Power Transformer: 315 kVA oil-immersed or dry-type transformer
- LV Section: MCCB, MCB, or ACB for outgoing distribution
- Enclosure: Galvanized sheet steel, aluminum, or stainless steel with IP54–IP65 protection
- Cooling: Natural air cooling (AN), or oil cooling (ONAN)
- Protection: Earth fault protection, surge arresters, overcurrent protection
- Metering and Relays (optional): For remote monitoring or SCADA integration
Technical Specification Table
| Parameter | Value |
|---|---|
| Rated Capacity | 315 kVA |
| Input Voltage (HV) | 11 kV / 22 kV / 33 kV (customizable) |
| Output Voltage (LV) | 400V / 230V (3 phase + N) |
| Cooling Type | ONAN (oil-immersed) / AN (dry-type) |
| Frequency | 50Hz / 60Hz |
| Impedance | ~4% (can vary) |
| Enclosure Type | Outdoor IP54–IP65, modular metal container |
| Installation Type | Pad mounted / Pole mounted |
| Protection Devices | Fuses, MCCB, Earth Fault Relay, etc. |
| Compliance Standards | IEC 62271, IEC 60076, ISO 9001 |
Applications of 315 kVA Mini Substation
- Urban residential areas
- Commercial buildings and malls
- Industrial workshops and processing units
- Construction and mining sites
- Agricultural pumping & irrigation systems
- Remote power distribution (rural electrification)
315 kVA Mini Substation Price Overview
The price of a 315 kVA mini substation can vary widely depending on configuration, brand, and additional features. Below are the key influencing factors:
Price Factors
- Transformer Type: Oil-immersed is cheaper than dry-type.
- Voltage Class: 11kV units are typically less expensive than 33kV models.
- Enclosure Material: Galvanized steel is more affordable; stainless steel costs more.
- Protection Level: Higher IP rating and smart protection relays increase the price.
- Switchgear Configuration: Manual LBS vs. motorized VCB affects the cost.
- Customization: SCADA, remote metering, and surge protection raise the price.
- Quantity and Shipping: Bulk orders and shipping distance matter.
Estimated Price Range
| Type | Approximate Price (USD) |
|---|---|
| 11kV Oil-immersed | $4,000 – $5,500 |
| 11kV Dry-type | $5,500 – $7,500 |
| 33kV Oil-immersed | $6,000 – $8,000 |
| 33kV Dry-type (IP65 rated) | $8,000 – $10,000 |
📌 Note: Prices are indicative and vary by manufacturer, location, and features.
Installation & Maintenance
- Plug & Play: Minimal civil work required; installation in <1 day.
- Low Maintenance: Periodic inspection and transformer oil tests (for oil type).
- Safety: Built-in earthing and overload protection.
Advantages at a Glance
- Quick deployment and commissioning
- Reduced land usage
- All-in-one compact design
- Safe and weatherproof enclosure
- Easy to relocate (for mobile substations)
Frequently Asked Questions (FAQs)
Q1: Is 315 kVA sufficient for residential buildings?
Yes. A 315 kVA transformer can support medium-sized residential communities or commercial spaces.
Q2: Can I choose between dry-type and oil-type transformer in mini substations?
Absolutely. Most suppliers offer both configurations depending on your environmental and fire safety needs.
Q3: Do I need a separate foundation for mini substations?
Usually, a simple concrete base or steel skid is sufficient. No large civil work required.