2 May
2025
Energeks
Noise in medium-voltage switchgear is not a detail – it’s an early warning signal that reveals risks, wear and hidden costs.
Imagine a medium-voltage switchgear that... whispers. It doesn’t roar, hum, or resonate. It whispers.
This isn’t science fiction – it’s the result of smart acoustic design. In the world of power engineering, noise isn’t just about comfort – it’s a signal that something could go dangerously wrong. Sound is the first warning. Its absence signals a kind of calm that builds trust in the installation.
At Energeks, we believe that designing a switchgear is an art of merging technology, safety and... silence. That’s why today we take a closer look at a topic few talk about, but which affects everything – from the durability of components to the health of the people working near the stations.
Who is this for? For investors, designers, and engineers who want to understand why noise from a switchgear is more than an annoyance – it can be a hidden threat.
What will you gain? Insight into how proper acoustic engineering can extend the lifespan of a switchgear, reduce the risk of failure, and ensure the comfort of the people working with it.
In this article:
Where noise in MV switchgear really comes from
The consequences of acoustic negligence
How to design so that silence becomes the standard
We invite you to read and share your insights. We would appreciate any feedback – because it's in conversation that great design happens.
Reading time: approx. 5 minutes
The acoustics you don’t hear: where noise in MV switchgear really comes from
Silence is not the absence of sound. It’s proof of well-engineered technology.
When you walk into an MV switchgear room, you don’t expect a concert. And yet, you often hear one – a hum, a hiss, a metallic screech. It’s the sound of devices trying to tell you: “something is working close to its limit.” In reality, the noise generated in medium-voltage switchgear is a complex and often overlooked technical issue, combining vibration physics, material engineering, and human ergonomics.
Unlike low-voltage systems, MV environments deal with currents up to 1250 A and short-circuit forces that can reach 21 kA. Under such conditions, even micro-resonance vibrations can escalate into clearly audible noise – and more importantly, into real technical risk.
Sources of noise in a switchgear – more than just “operational hum”
Electromagnetic vibrations – Alternating current at 50 Hz, especially in systems with large inductances, generates forces acting on conductors and cores. In fault conditions, these forces increase exponentially.
Electric arc – Although brief, it is accompanied by an explosive acoustic impulse. In SF₆-insulated switchgear, pressure-relief flaps should disperse the excess energy – but if poorly designed, the acoustic effect becomes significant.
Structural resonance – Any unsecured plate, unreinforced frame, or thin sheet metal can behave like a resonating membrane – amplifying even small noises to audible levels.
Ventilation and airflow – In switchgear with forced cooling, duct acoustics play a crucial role. Aerodynamic noise can reach 70–80 dB even without a fault occurring.
Piezoelectric effects and micro-contact vibrations – A contact not tightened with the correct torque (e.g. 39 Nm for M10 bolts) can generate local vibration. Over time, this leads to micro-arcing and localized overheating.
How much noise is too much?
50–60 dB(A) – acceptable level in normal working conditions
60–75 dB(A) – requires the use of damping materials and structural insulation
Above 85 dB(A) – exceeds occupational safety limits; personal protective equipment is required
95–110 dB(A) – critical level, possible during internal arc or fault; requires immediate intervention
In practice, this means that a switchgear generating 80 dB of noise for eight hours a day exposes personnel not only to permanent hearing damage but also to mental fatigue, reduced focus, and operational errors. And a single error in an MV environment can have serious consequences.
When sound becomes a threat: the consequences of acoustic negligence
“It’s just noise” – or is it?
In MV switchgear design, acoustics are often treated as an afterthought – background noise, an aesthetic issue. But physics doesn’t recognize “background.” Noise is energy. Energy that resonates, shakes metal components, weakens structures, shortens device lifespans, and endangers human health.
What may seem like harmless acoustic effects become ticking time bombs – literal and figurative. Below, we examine the consequences of poor acoustic design on three levels: technical, human, and regulatory.
1. Technical consequences: micro-vibrations that destroy silently
Micro-vibrations are the invisible enemy of infrastructure. They appear at the level of single contactors, busbars, or even bolt joints. Due to recurring resonances (even with amplitudes in the micron range), we may observe:
Loosening of connections (a phenomenon known from railway tracks and bridges – but on a smaller scale)
Oxidation of contacts, increasing transition resistance
Localized heating of contacts → micro-arcs → accelerated wear
Example: improperly tightened busbar joints (e.g. below 70 Nm for M12 bolts) can lose geometric stability within six months of operation, reducing contact area by 40% and increasing short-circuit risk.
Ongoing resonance load can also affect automation equipment – e.g. relays, voltage presence indicators, auxiliary switches. Faults in these circuits may remain undetected until a critical failure occurs.
2. Ergonomic and psychophysical consequences: sound that wears people down
Noise affects people cumulatively. What does that mean?
Continuous noise above 70 dB(A) for 8 hours = hearing loss after several years
Impulse noise above 100 dB(A) (e.g. during an arc or high-current switching) = instant damage to the eardrum
Variable-frequency noise (above 2000 Hz) = increased cortisol levels, irritability, and decision-making errors
For switchgear operators or maintenance staff, noise also creates psychological strain: loss of concentration, misreading displays, skipped procedures.
In environments where precision procedures are essential (e.g. disabling safety systems), even a second of inattention can lead to tragedy.
3. Regulatory consequences: non-compliance = cost and liability
Switchgear that exceeds noise regulations or fails to meet IEC/CEI standards exposes investors and manufacturers to:
Mandatory modernization or dismantling
Rejection by national regulators or ISO auditors
Non-compliance with occupational safety laws (e.g. Polish Regulation Dz.U. 2020 poz. 1356)
Civil or criminal liability in the event of a workplace accident
Reminder – according to IEC 62271-1:
"Switchgear design must ensure limited sound emissions to levels enabling safe, comfortable, and uninterrupted operation over the intended lifetime."
Additionally, under EU Machinery Directive 2006/42/EC, devices emitting over 80 dB must be labeled with noise levels and include user manuals specifying protective measures.
Long-term impact of “quiet risk”
“You know something’s wrong when your switchgear starts sounding like a badly tuned radio.” – technician from a power plant in Opole
The real issue with acoustic neglect isn’t single-point failures, but... repetition. Switchgear operating under resonance conditions statistically exhibits:
38% higher failure rate after 24 months
27% higher maintenance costs
45% shorter lifespan of moving components (e.g. circuit breaker drives)
For investors, this means:
Production downtime
Employee compensation claims
Risk of failing certification audits
The domino effect – when one sound triggers a chain reaction
Noise = vibration. Vibration = looseness. Looseness = contact heating. Heating = micro-arcing. Micro-arcing = short-circuit. Short-circuit = power outage. Power outage = halted production.
Neglecting acoustic emissions activates what systems engineers call a hidden defect domino effect.
And here lies the essential question: if all of this is predictable and preventable – why does no one talk about it?
Prevention over reaction: when silence becomes an investment
The best acoustic risk management strategy is... prevention. In practice, this means:
Choosing switchgear that complies with CEI EN 62271-200
Evaluating sound levels during FAT (Factory Acceptance Test)
Using passive noise-damping technologies (e.g. acoustic absorbers, arc dampers, vibration isolators)
Performing regular torque inspections (every 6–12 months)
If you want to understand what to really look out for in 2025, how to interpret internal arc markings, what the difference is between full-compatible and modular switchgear, and what's in it for you - this will be a good read:
The ultimate 2025 buying guide for switchgear: What your vendor won’t tell you
How to design silence: best practices for MV switchgear
In a world of technology where reliability and efficiency matter most, the acoustics of MV switchgear are no longer a luxury – they are a safety requirement. “Silent construction” is becoming a mark of quality and longevity. Silence in the switchgear room doesn’t mean the absence of sound – it reflects a well-engineered system managing vibrations, airflow, enclosure structure, and mechanical connections.
Below is a set of best practices based on both international standards (IEC, CEI, ISO) and Energeks' hands-on experience with implementing the N series switchgear by ICET.
1. Structural design – a frame that doesn’t resonate
Every switchgear unit operates under dynamic forces – both electromagnetic (from current flow) and mechanical (from operation and switching). That’s why the first step toward silence is the right load-bearing structure.
Using a galvanized steel frame with high torsional stiffness helps eliminate frame-wide resonance. ICET switchgear applies reinforced profiles to minimize vibrational susceptibility.
Mounting holes and screw connections are arranged irregularly – a deliberate engineering decision that avoids interference and overlapping of acoustic waves.
Instead of a single continuous enclosure, a modular segment design is used, allowing each compartment (e.g. busbar, measurement, circuit breaker) to absorb vibration independently.
Silence starts with metal – its geometry, method of joining, and the precisely defined thickness of the sheets. Even 1 mm more in a critical spot can reduce resonance by 3–5 dB.
2. Partitions that isolate physically and acoustically
In traditional switchgear, internal compartments are acoustically connected, which encourages the spread of high-frequency sounds (above 1 kHz). The result? The switchgear turns into a resonant box.
In modern designs like the ICET N series:
Each compartment includes solid metal partitions with high resistance to pressure waves
Separators are installed both vertically and horizontally, limiting sound propagation across multiple axes
Key areas are filled with sound-absorbing materials, such as class B2 polyurethane foams or mineral wool
Additional gaskets on compartment doors ensure protection not only against dust and moisture (IP3X/IP2X), but also localized noise dampening
This layout reduces noise between the circuit breaker and operator compartments by 15–20 dB – enough so that, during an internal arc, personnel 3 meters away are not exposed to levels exceeding 85 dB.
3. Arc dampers and directional pressure relief channels
During an internal arc fault, pressure and sound waves can reach 130–140 dB within milliseconds. Effective measures must include:
Decompression channels to safely direct overpressure gases (including SF₆) away from personnel
Pressure relief flaps that open only when the dynamic threshold is exceeded
Sound absorbers in the exhaust zones, such as meshes or composite panels with noise-dampening fillings
In the ICET N series, specially designed internal surfaces help scatter the pressure wave, reducing its direct impact on front doors.
These are not only safety features – they also enhance comfort. Thanks to these measures, the noise from a fault event remains below the permissible limit for acoustically controlled environments (under 100 dB for ≤ 1s).
4. Busbar and terminal mounting – silence at the joints
Current-carrying components like busbars and cable connections are subject to frequent mechanical and electrical stress. High-current vibrations can produce acoustic effects if joints are not properly designed.
Best practices include:
Using busbars with vibration-minimizing cross-sections (often silver- or tin-plated, with rounded edges)
Defining torque values precisely – e.g., M12 bolts: 70 Nm, but reduced to 55 Nm when connecting to SF₆-insulated IMS disconnectors
Applying spring washers to absorb part of the vibrational energy
Avoiding flexible cables without anchoring points – their “waves” can resonate and transmit vibration to adjacent sections
The correct installation of cables and busbars ensures not just effective current flow but lasting silence – and that means fewer faults, smoother operation, and longer device lifespan.
5. Damping materials – a protective layer for ears and equipment
Finally, a critical component in acoustic control is the use of damping materials – both inside panel doors and between compartments.
The ICET N series uses:
Open-cell melamine foams, rated class A per EN ISO 11654
Perforated steel sheets with bitumen mats, reducing enclosure resonance
Multilayer gaskets at doors and covers, acting as both acoustic barriers and environmental seals
Composite “sandwich” panels to minimize sound transmission between sections
This approach enables not only full compliance with regulations but often outperforms them. In some installations, the noise level during normal operation of the ICET N series circuit breaker was measured at just 60 dB – quieter than an average conversation.
The art of conscious choices
Designing silent switchgear is not about compromises – it is the result of intentional engineering decisions. Silence is the outcome of synergy between materials, geometry, assembly, and anticipating fault scenarios. Investing in systems that not only meet standards but exceed them is an investment in long-term safety, stability, and performance.
Silent but powerful
In industrial energy environments, where every design decision affects people’s safety and operational budgets, silence is no longer a luxury. Silence has become a strategic value. It reflects technological maturity, precision in execution, and a deep understanding of hidden risks.
A well-designed MV switchgear does more than function – it stays quiet while working, and alerts clearly when something goes wrong. It doesn’t confuse. It provides peace of mind – to the operator, the investor, and the maintenance team. That’s what true quality is about.
If you’re considering a modernization project or planning a new infrastructure today – we’re here to help. Whether you need a ready-to-go solution or are still analyzing technical requirements, we are ready to advise, support, and share our expertise.
Visit our current product range, where you’ll find units engineered not only for electrical performance but for acoustic excellence.
Check the availability of oil transformers – many models with a 5-year warranty are ready for immediate deployment, with no lead time.
And if you’re looking for daily inspiration, expert insights, and a space to share practical challenges – join our Energeks community on LinkedIn. We don’t just talk about equipment. We talk about the future of energy.
Together – quieter, smarter, safer.
Sources:
Cover Photo: Muhammet Colak/pexels-7360328
IEEE Xplore – Acoustic Emissions in MV Switchgear
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