What is Undervoltage?
Definition: The average voltage of the power system is continuously lower than the nominal voltage (such as 230V/220V/110V), but the power is not completely cut off.
Key differences:
Undervoltage: The voltage is temporarily reduced, and the equipment can still operate but the efficiency is reduced.
Blackout: The power is completely cut off and the voltage drops to zero.
Note: Some materials mix “Undervoltage” and “voltage drop (Sag)”, but they actually refer to the low voltage state without a power outage.
Why is Undervoltage more worrying?
Hidden damage to equipment
Increased current: To maintain power (P=V×I), the equipment is forced to absorb more current, resulting in overheating and insulation aging.
Motor equipment (such as refrigerators and air conditioners): Coil and bearing wear accelerates, reducing life by 30% to 50%.
Electronic components: Capacitors, transistors, etc. are prone to breakdown due to overload and may be permanently damaged.
Economic and safety risks
Home scenarios: Frequent repair or replacement of electrical appliances increases long-term costs.
Industrial scenarios: Failures of transformers, compressors, etc. may trigger a chain reaction, causing production lines to shut down and affecting the power supply of the entire community.
Grid stability issues
Undervoltage is often a precursor to grid collapse. Although deliberate power restrictions can avoid power outages, long-term low voltage will increase the risk of collective equipment failure.
Common causes of undervoltage
| Cause type | Specific scenarios | Cases |
| Surge in electricity demand | Peak electricity demand periods (such as summer evenings) | A sudden drop in voltage caused by concentrated air conditioning startup |
| Insufficient grid capacity | Old or poorly planned infrastructure | Unstable voltage in remote areas |
| Extreme weather | Storms damage transmission lines | Local undervoltage caused by trees crushing power lines |
| Artificial power rationing | Power companies proactively reduce voltage to prevent network collapse | Rotating power cuts to cope with energy shortages |
How to deal with undervoltage?
Immediate measures
Disconnect high-power devices (such as ovens and motors) to reduce circuit load.
Use a multimeter to monitor the voltage and be alert if it is continuously below 85% of the nominal value.
Long-term protection
Install voltage protector:
Volt Guard: Automatically cuts off ultra-low voltage power to protect sensitive appliances.
Fridge Guard: Designed specifically for refrigerators to prevent compressors from running at low voltage.
Upgrade the power distribution system: Add a voltage regulator stabilizer or UPS to ensure stable voltage.
Industrial-grade solutions
Use a dynamic voltage restorer (DVR) to compensate voltage in real-time.
Standby generators to deal with sudden low-voltage events.
Common misunderstandings clarified
“Undervoltage is different from voltage drop”: both are voltage reduction phenomena, and the difference in terminology comes from industry habits (such as power engineering vs. daily language).
“Short-term undervoltage is harmless”: Even if it lasts for a few minutes, it may cause cumulative damage to motor equipment.
Summary
The hidden and cumulative destructive power of undervoltage makes it more of a concern than power outages. Risks can be effectively reduced by actively monitoring, installing protection devices, and upgrading grid facilities. For home users, investing in a reliable voltage protector (such as Sollatek products) is the most cost-effective choice.
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