Prefabricated Substations: Temperature Control & Environmental Adaptability

In global power systems, prefabricated substations are widely used across various distribution networks. These enclosures integrate transformers, switchgear, and control units, and their operational reliability depends on the effectiveness of the internal environmental control system. Environmental parameters such as temperature and humidity, if they deviate from the allowable range for the equipment, can lead to reduced insulation performance, shortened component lifespan, or system failure.

This article provides a technical explanation of the working principles of prefabricated substation temperature control systems, design solutions for different climatic conditions, and the core elements of environmental adaptability design.

1. Basic Principles and Composition of Temperature Control Systems

The primary function of a prefabricated substation temperature control system is to maintain internal environmental parameters within the range specified by the equipment manufacturer. The system achieves stable temperature control within the enclosure through continuous monitoring and automatic adjustment.

1.1 Basic System Composition

A temperature control system consists of the following main components:

Temperature Sensors: Installed in key areas inside the enclosure to collect real-time temperature data.

Control Module: Receives signals from the sensors, compares them with set values, and outputs control commands.

Actuating Mechanisms: Includes air conditioning units, heaters, ventilation fans, etc., which act according to the control commands.

Insulation Structure: The enclosure's building envelope uses insulating materials to reduce heat exchange between the interior and exterior.

1.2 Control Logic

The system employs a closed-loop control method. The control module compares the measured temperature against the set range. When the temperature deviates from the set point, it automatically activates the corresponding cooling or heating equipment until the temperature returns to the normal range.

2. Design Solutions for Different Climatic Conditions

Prefabricated substations are used in diverse environments, ranging from severe cold regions to humid coastal areas, with significant variations in climatic conditions. The temperature control system must be designed based on the specific environmental conditions of the project site.

2.1 Severe Cold and Low-Temperature Environments

Applicable for regions where winter temperatures fall below -20°C.

Design Considerations:

Enhanced Insulation Performance: The enclosure's building envelope uses high-density insulation materials. The thickness of the sandwich panel is calculated based on the local minimum temperature. Insulation materials must meet flame retardancy requirements, with a thermal conductivity ideally below 0.035 W/(m·K).

Auxiliary Heating System: Industrial-grade electric heaters are installed in equipment areas and battery cabinets. Heater operation is automatically controlled by a temperature controller, with the activation set point typically at 5°C. Heating elements must maintain a safe distance from equipment.

Low-Temperature Material Selection: Enclosure seals use low-temperature resistant silicone rubber or EPDM rubber to ensure sealing performance remains effective in -40°C environments. Structural steel must meet the impact toughness requirements for the corresponding low-temperature grade.

Snow and Ice Protection Measures: The enclosure roof is designed with a drainage slope of not less than 5% to prevent snow and water accumulation. Cable entry points are sealed to prevent snowmelt infiltration.

2.2 Hot-Humid and Salt Spray Corrosion Environments

Applicable for coastal areas, islands, and regions with high humidity.

Design Considerations:

Anti-Corrosion Coating System: The enclosure steel structure undergoes hot-dip galvanizing with a coating thickness not less than 80μm. The exterior surface is coated with a multi-layer anti-corrosion system, including epoxy zinc-rich primer, epoxy micaceous iron intermediate paint, and polyurethane topcoat. Fasteners are made of stainless steel.

Dehumidification Configuration: Industrial-grade dehumidifiers are installed, with a capacity matching the internal volume of the enclosure. The dehumidifier operates in conjunction with the air conditioning system to maintain relative humidity inside the enclosure below 60%, preventing condensation.

Ingress Protection Rating: The enclosure's protection rating is not less than IP54. Cable entries use sealing modules or glands, and all doors are fitted with sealing gaskets.

Material Selection: Internal metal components preferentially use stainless steel or surface-treated aluminum alloy. Electrical component selection requires verification through salt spray testing.

2.3 High-Altitude Environments

Applicable for areas with an altitude of 1000 meters or more above sea level.

Design Considerations:

Clearance Correction: External insulation distances for electrical equipment must be corrected based on the actual altitude. According to relevant standards, for every 1000-meter increase in altitude, electrical clearances should be increased by 8%-13%, or components with higher creepage distances should be selected.

Heat Dissipation Compensation: Air density decreases with increasing altitude, reducing cooling efficiency. The cooling capacity of air conditioning units must be corrected for altitude. Increasing the heat sink area or employing forced ventilation may be necessary.

UV Resistance Treatment: Exterior coatings, seals, and labeling materials should be selected from products with stable UV resistance to prevent material degradation.

2.4 Windblown Sand and Dusty Environments

Applicable for deserts, gobi areas, and regions with heavy industrial pollution.

Design Considerations:

Sealing Structure: Doors use labyrinth-type sealing structures to increase the path length for dust ingress. All joints are filled with sealant.

Micro-Positive Pressure System: Where budget permits, a micro-positive pressure device can be configured. Filtered clean air is continuously supplied into the enclosure, maintaining internal pressure slightly above external pressure to prevent dust ingress.

Filtration Devices: Fresh air intakes for air conditioning and ventilation openings are equipped with removable, washable filters. Filtration accuracy is determined based on the site's specific dust particle size.

3. Operation and Control Modes of Temperature Control Systems

3.1 Automatic Control

The control system uses a programmable logic controller to automatically adjust equipment operation based on preset parameters. The control panel displays real-time internal temperature, humidity, and equipment operating status.

3.2 Operating Modes

Cooling Mode: Activates the air conditioner when the internal temperature exceeds the set upper limit.

Heating Mode: Activates the heater when the internal temperature falls below the set lower limit.

Dehumidification Mode: Activates the dehumidifier when the internal humidity exceeds the set value.

Ventilation Mode: Activates fans for air exchange when external environmental conditions are suitable.

3.3 Parameter Settings

The temperature set range is determined based on equipment requirements, typically 5°C to 40°C. The upper limit for humidity set points is typically 70%-80%, with the specific value determined by equipment requirements and local climatic conditions.

4. Core Elements of Environmental Adaptability Design

The environmental adaptability design of a prefabricated substation is fundamental to ensuring its long-term stable operation. The following aspects require focused attention during the design process:

4.1 Design Input Based on Site Data

Before design, meteorological data for the project location should be obtained, including:

Annual extreme maximum/minimum temperatures

Relative humidity range

Altitude

Pollution level

Basic wind speed

Maximum snow depth

Design parameters are determined based on this data to avoid over-design or under-design.

4.2 Insulation and Sealing Performance

Insulation performance directly impacts the energy consumption of the temperature control system. The type and thickness of insulation materials should be rationally selected, and the overall heat transfer coefficient of the enclosure should be calculated. Sealing performance affects dust and moisture prevention effectiveness; the sealing reliability of all joints must be ensured.

4.3 Equipment Selection and Matching

The capacity of temperature control equipment should be determined based on the enclosure's heat load calculation. Heat load includes:

Heat transfer through the building envelope

Equipment heat dissipation

Fresh air load

Solar radiation heat gain

Equipment selection should include an appropriate margin but should not be oversized to avoid frequent start-stop cycles.

4.4 Type Test Verification

Upon design completion, environmental adaptability should be verified through relevant type tests, including:

High-temperature operation test

Low-temperature operation test

Damp heat cyclic test

Salt spray test

Ingress protection test

Relevant standards such as IEC 62271-202 may be referenced for testing.

5. Conclusion

The temperature control system is a crucial guarantee for the reliable operation of prefabricated transformer substations. During the design phase, appropriate technical solutions and equipment configurations must be selected based on the specific climatic conditions of the project location. Through rational design and verification, the internal environment of the enclosure can be maintained to meet equipment operating requirements.

Environmental adaptability design encompasses multiple aspects, including insulation, sealing, corrosion protection, and heat dissipation. All factors must be considered comprehensively to form a systematic solution. Through standardized selection, calculation, and test verification, the suitability and long-term operational reliability of prefabricated substations under different climatic conditions can be ensured.

For technical assessment and solution design for specific project environmental conditions, welcome to contact our engineering department. 

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