Environmental Impact on Switchboards: Complete Engineering Guide

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Introduction

Environmental impact is a topic that often gets overlooked during the design phase of a switchboard. While designers usually consider ambient temperature as a primary environmental parameter, several other critical conditions—such as humidity, salinity, and pollution levels—play an equally important role in ensuring the long-term reliability of MV switchboards.

Why do these conditions matter?

Most switchboards are not installed in controlled or air-conditioned environments. They are typically placed in naturally ventilated rooms without ambient control, or even outdoors under open sky when designed for outdoor applications. In such cases, if the surrounding air exhibits high humidity, high salinity, or heavy pollution, the switchboard is effectively operating in adverse environmental conditions.

These environmental factors significantly influence the performance, life expectancy, and insulation reliability of any switchboards. This is the reason for discussing the environmental impact as an important factor while designing LV or MV switchboards. Environmental impact can vary for LV and MV switchboards, especially the issue of condensation inside the enclosure.

Let’s examine the environmental impact of each parameter in detail and understand how it impacts switchboard design, installation, and long-term operation.

Humidity and Its Impact

Why it matters:

High humidity increases the moisture content in the air, leading to surface condensation on insulation parts, busbars, terminations, and mechanisms. This issue is more prominent in MV Switchboards because of low current

Key impacts on switchboards:

  • Insulation breakdown risk: Moisture reduces surface insulation resistance and can cause partial discharge, surface tracking, or flashover.
  • Corrosion of metallic parts: Steel parts, terminals, and joints corrode faster in humid environments.
  • Degradation of insulating materials: Epoxy, FRP, and polymers absorb moisture, weakening dielectric strength.
  • Functional issues: Mechanisms such as spring-charged motors and interlocks may jam due to rust and micro-corrosion.

Design considerations:

  • Adequate number of space heaters controlled by thermostats or humidistats to stop condensation
  • Adequate ventilation or forced air circulation to reduce the inside and outside temperature difference in the switchboard enclosure. This will help prevent condensation inside the enclosure.
  • High-creepage insulators.
  • Use of tropicalized varnish or epoxy coating.

Salinity and Corrosive Atmosphere

Where this occurs:
Coastal areas, offshore installations, solar/wind plants near the sea, and industrial zones with chloride-containing emissions.

Key impacts:

  • Accelerated corrosion: Salt acts as an electrolyte, drastically increasing the corrosion rate of copper, aluminium, and steel.
  • Surface tracking: Salt particles absorb moisture, form conductive film and cause tracking during switching surges.
  • Failure of MCCBs/VCBs mechanisms: Fine salt deposits enter moving parts, reducing reliability.
  • Reduced lifespan of CTs/PTs/Insulators: Salt fog increases leakage currents and dielectric stress.

Design considerations:

  • High-grade SS hardware (SS304/SS316)
  • Epoxy powder coating with high salt-spray rating. Follow the painting process according to the corrosion category of the location.
  • Salt-mist tested components (IEC 60068-2-52)
  • Sealed switchgears like SSIS, GIS, RMU, or any sealed-for-life products for extreme environmental conditions.
  • Enhanced creepage distance with high creepage insulators and more spacing between conductive parts.

Pollution & Dust Levels

Common environments:
Cement plants, thermal power plants, mining sites, chemical industries, metallurgical plants, and desert regions.

Key impacts:

  • Conductive dust deposits → severe risk of flashover during moisture events.
  • Reduction in creepage & clearance effectiveness due to dust accumulation and easy absorption of moisture by dust.
  • Air filters are clogging in air-ventilated switchboards, causing overheating.
  • Corrosion due to acidic pollutants like SO₂, NOx, industrial fumes. They form acidic solutions, combining with the water content in the humidity.

Design considerations:

  • Filters with periodic replacement cycles
  • High creepage insulators, RTV-coated bushings
  • IP4X / IP5X / IP54 designs depending on dust severity
  • Pressurised or sealed enclosures for extreme dust conditions
  • Regular cleaning by dry air jet or vacuum

Temperature — the Most Considered Parameter, Yet Incomplete Alone

Even though ambient temperature is widely considered, its combined environmental impact with humidity, salinity, and pollution is often ignored.

Example:

  • A panel designed for 50°C may still fail at 35°C if humidity is >95% with condensation cycles.
  • A panel with an adequate temperature design may suffer severe corrosion if the salinity is high.

Temperature stress impacts:

  • Accelerated ageing of insulation (Arrhenius law)
  • Increased conductor resistance due to higher temperature, leading to further heating.
  • Failure of electronic relays without proper cooling.
  • Derating of busbars and breakers.

Conclusion: Why Environmental Design Matters

Switchboards are expected to operate reliably and safely for 20–30 years, often with minimal human intervention. Over this long service life, the surrounding environment becomes one of the most dominant factors influencing operational reliability. The environmental impacts should not compromise the performance and reliability of the switchboard.

Environmental conditions have a direct and cumulative impact on:

  • Dielectric performance – through moisture, pollution deposits, and tracking, which reduce insulation strength.
  • Mechanical reliability – as corrosion, dust, and temperature cycles degrade moving parts, interlocks, and operating mechanisms.
  • Corrosion rate – accelerated by humidity, salinity, chemical pollutants, and condensation cycles.
  • Expected lifespan – as environmental stressors accelerate the ageing of insulation, coatings, and metallic components.
  • Safety during abnormal conditions – including fault events, where weakened insulation or corroded parts significantly increase the risk of catastrophic failures.

Therefore, a robust switchboard design must go far beyond temperature considerations alone. It must adopt a holistic environmental impact engineering approach that accounts for the combined effects of humidity, salinity, pollution, dust, and temperature cycles from the design stage through installation and long-term maintenance.

Switchboards designed with comprehensive environmental impact considerations not only deliver higher reliability but also ensure safer operation, reduced lifecycle cost, and sustained performance in the harshest conditions.

Pictorial Summary: Environmental Impact

Environmental Impact

Further Reading

International Standards (IEC)

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