Transformers & The Challenge of Electrical Noise from Electromagnetic interference
- Mai Tanjitpiyanond
- Feb 13
- 3 min read
Key Takeaways
EMI affects power systems – Electricity traveling through transmission lines is filled with Inter-System EMI (from lightning, radio signals) and Intra-System EMI (from electrical devices like EV chargers and switching power supplies).
Major EMI issues – Voltage instability (Voltage Fluctuation, Power Frequency Variation, Waveform Distortion) impacts the performance of electrical devices, especially audio systems and industrial equipment.
Common Mode Noise – Electrical noise that comes with power supply degrades sound and image quality. Even rewiring cannot completely eliminate the issue.
Ways to reduce EMI – Isolation Transformers, Harmonic Filters, and Ferroresonance Systems help minimize noise interference and enhance power stability.
STT Solutions – Pulito Powerline Conditioner and Ferroresonant Transformer are designed to reduce electrical noise and improve power quality for both industrial applications and high-end audio systems.
Linear Transformers
Linear transformers, including EI, Toroidal, Cut-Core, and R-Core, operate based on electromagnetic induction to transfer energy between circuits. Each type is designed for specific voltage levels (100V, 115V, 230V) and frequencies(50Hz, 60Hz, or 400Hz), ensuring stability, accuracy, and durability for different applications.
In controlled laboratory environments, transformers are tested under ideal conditions with regulated waveforms, frequencies, and temperatures. However, real-world electrical systems are far more unpredictable, facing voltage fluctuations and power disturbances.
The Impact of Inter-System Electromagnetic interference
As electricity travels long distances from power plants through transmission lines, it accumulates electromagnetic interference (EMI) from various external sources. This Inter-System EMI can lead to unstable voltage, reduced power quality, and electrical noise affecting all connected devices.
Common Sources of Inter-System EMI:
✔ Natural disturbances – Lightning strikes
✔ Electromagnetic signals – Radio waves, radar, microwaves, and data transmissions
Most of this interference appears as Common Mode Noise, where voltage, phase, and direction remain the same on both Line and Neutral conductors. By the time electricity reaches end-users, it is already contaminated with unwanted electrical noise.
Intra-System EMI: Noise Generated Within the Power Network
Unlike Inter-System EMI, Intra-System EMI originates within local electrical networks. Every device—such as industrial machinery, household electronics, and entertainment systems—contributes additional electrical noise.
High-powered appliances like switching power supplies, inverters, and EV chargers create distortions that degrade the performance of sensitive equipment, including audio systems, home theaters, and precision instruments. This makes electrical noise unavoidable, no matter how well a building’s electrical wiring is designed.
Key Types of Electrical Noise:
1️⃣ Voltage Fluctuation – Unstable voltage levels
2️⃣ Power Frequency Variation – Fluctuations in AC frequency
3️⃣ Waveform Distortion – Irregularities in electrical waveforms (harmonics)
Noise interference exists in two forms:
✔ Differential Mode Noise – Disturbance between two conductors
✔ Common Mode Noise – Interference affecting both Line and Neutral conductors in the same phase
How to Reduce EMI & Improve Power Quality
Since electrical noise, particularly Intra-System EMI, primarily originates from interconnected electrical devices, implementing preventive and corrective measures is crucial. Effective solutions include:
🔹 Optimizing circuit design to minimize EMI generation
🔹 Enhancing materials and equipment construction to reduce emitted interference
🔹 Installing noise filtering devices, such as:
✔ Regenerator – Rebuilds and purifies AC power supply
✔ Isolation Transformer – Electrically isolates power circuits, preventing EMI contamination
✔ Harmonic Filter – Suppresses harmonic noise in both passive and active forms
✔ Ferroresonance System – Regulates voltage stability and mitigates power fluctuations
STT: High-Quality Transformer Solutions for Reliable Power
At Saengthong Transformers (STT), we understand the challenges of electrical noise in real-world power systems. We design and manufacture transformers and power conditioning solutions to effectively combat these issues:
🔹 EI & Toroidal Transformers – Engineered to reduce EMI and improve power stability
🔹 Isolation Transformer – Eliminates common mode noise, ensuring clean power delivery
🔹 Pulito Powerline Conditioner – Filters electrical noise and enhances audio & home theater performance
🔹 Ferroresonant Transformer – Protects industrial systems from voltage surges and maintains power reliability
Contact Us Today! Get expert advice and find the right transformer for your project.
Email: info@sttransformers.com
Website: www.sttransformers.com
Line: @sttransformers
📌Next Article
In the upcoming article, we will discuss Waveform Distortion, a major issue affecting household power users. We will also explain how Isolation Transformers (Pulito) and Ferroresonance Transformers work to enhance power qualityand minimize electrical disturbances.
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