Understanding Substations: Indoor vs. Outdoor Substations

Substations play a crucial role in the electrical power system, transforming high-voltage electricity from transmission lines into lower voltages suitable for distribution and customer use.

Key Equipment in a Substation

A substation comprises various essential components, including:

• Instrument Transformers: Current transformers (CTs) and potential transformers (PTs)
• Conductors and Busbars
• Insulators and Isolators
• Lightning Arresters
• Circuit Breakers and Relays
• Capacitor Banks and Batteries
• Wave Traps and Carrier Current Equipment
• Surge Protection Devices
• Metering and Indicating Instruments
• Switchyard and Outgoing Feeders

One of the most critical parts of a substation is switchgear, which ensures the safe operation of electrical circuits by making, breaking, and carrying normal load currents. Compact substation manufacturers play a key role in enabling efficient energy transformation from medium voltage (MV) to low voltage (LV) in secondary distribution systems.

Indoor vs. Outdoor Substations

Substations are broadly categorized into indoor and outdoor types, depending on their installation environment.

What is an Indoor Substation?

As the name suggests, an indoor substation is located inside a building or enclosed space. Typically, these substations operate at voltages of up to 11,000V. However, in areas with high contamination or pollution, the voltage level can extend up to 33,000V to 66,000V.

Examples of indoor substations include storage battery substations and fire protection substations equipped with water buckets and fire extinguishers.

What is an Outdoor Substation?

In outdoor substations, all electrical equipment is installed in open spaces. These substations handle voltages ranging from 55kV to 765kV and are commonly found in grid substations.

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Key Differences Between Indoor and Outdoor Substations

Factor	Indoor Substation	Outdoor Substation
Location	Installed inside a building or enclosed space	Installed in an open area outside
Construction	Complex design with multiple compartments for control, metering, protection, and busbars	Simpler design but requires more space
Voltage Levels	Typically up to 11,000V, but can extend to 33,000V - 66,000V	Operates between 55kV - 765kV
Equipment Visibility	Equipment is enclosed and not easily visible	Equipment is installed in open space and clearly visible
Fault Detection	Faults are easier to detect due to controlled conditions	Faults can be harder to identify and troubleshoot
Maintenance	High maintenance due to complex design	Lower maintenance but requires more effort to handle environmental factors
Repair & Replacement	Difficult due to enclosed setup	Easier access but more time-consuming repairs
Safety	More secure due to enclosed environment	Less safe due to exposure to external conditions
Clearance Requirements	Lower clearance as components are insulated	Higher clearance required as components like busbars and overhead lines are exposed
Space Requirements	Requires less space due to compact design	Requires more space due to larger equipment layout
Cost	Higher due to construction and insulation requirements	Lower as it requires fewer enclosures and simpler infrastructure
Types	- Battery substations - Fire-fighting substations	- Pole-mounted substations - Foundation-mounted substations

Outdoor Substation Types

1. Pole-Mounted Substations
   • Uses outdoor-rated equipment
   • Protected by high-voltage fuses
   • Includes low-tension switches for low-voltage lines
2. Foundation-Mounted Substations
   • Handles heavier equipment
   • Requires careful site selection for stability

Which Substation is the Better Choice?

• Indoor substations are ideal for urban areas, where space is limited, and safety is a priority.
• Outdoor substations are better suited for rural and industrial settings, where space is abundant, and high voltages are required.

Before selecting a substation type, it's essential to evaluate factors such as space availability, voltage requirements, maintenance capabilities, and safety considerations.

If you need expert guidance in choosing the right switchgear and substation equipment, partnering with a reliable switchgear manufacturer ensures optimal performance and long-term efficiency.

Professiona Switchgear supplier and manufacturer 

1. Zhejiang GONGSHUN Electrical Co.,Ltd (electricgs.com), Our company was founded in the late 1990s, specializing in the production of inflatable cabinets, SF6 inflatable cabinets, and various high and low voltage complete sets of electrical equipment. It has multiple subsidiaries under its jurisdiction, including high-voltage load switch branch, high-voltage circuit breaker branch, high-voltage fuse branch, and technology development branch.Our technical expertise, comprehensive product portfolio and long-term rich experience are helping many customers in need to solve their power problems. We’re happy to help at any time.  Whether you need application product advice or technical assistance, our global service team is committed to providing you with the right support. For more technical information about medium voltage earthing switch, feel free to contact us, send an email to gongshun@electric-cn.com 
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