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ITGlossary · Power quality
Noise (Electrical)
Unwanted high-frequency disturbances on the supply voltage, e.g. from motors or power supplies, which UPS systems and line conditioners filter out.
Technical level:Intermediate
High-frequency fluctuations often ride on top of the mains sine wave; this is electrical noise. It comes from motors, switch-mode power supplies, inverters, lighting or even distant lightning discharges, and it travels along cables or is radiated through the air.
In practice, noise causes computer freezes, data errors, interference in audio and video, and premature wear of electronics. The EMI/RFI filters in UPS units and surge-protected power strips reduce it, while a double-conversion UPS isolates the load from it almost completely, because it generates its output voltage from scratch.
A common mistake is poor or missing earthing: without a proper earth connection, even the best filter cannot work as intended.
Questions that mention it
All frequently asked questionsHow much noise does a UPS make?
Tescom UPS units are designed for minimal noise (in decibels) in spaces where people are present.
UPS or surge protection strips (surge arresters): what is the difference?
Surge protection strips protect equipment from overvoltages and voltage spikes, and some also filter noise. They do not protect against undervoltage or power cuts, and they give no runtime. A UPS keeps equipment running during a cut and, depending on its type, also corrects the voltage. So they serve different needs and are often used together.
Related articles
Related terms
- Line ConditionerA device that improves power quality by regulating voltage and filtering noise.
- Power ConditioningTechniques such as EMI/RFI filtering, surge protection and AVR that correct voltage problems before they reach the load.
- RFI — Radio Frequency InterferenceA subset of EMI: high-frequency noise from electronic equipment that can disturb radio, Wi-Fi and other devices.
- Automatic Voltage Regulator (AVR)A device that automatically maintains a constant voltage level to protect electrical equipment from fluctuations.
- Electromagnetic Interference (EMI)Unwanted electrical noise or interference that can disrupt electronic equipment operation.
- Single-phase PowerAn electrical system with one alternating current (AC) voltage phase, commonly used in homes and offices.