Introduction
When it comes to protecting our electrical systems, we often think of voltage stabilizers and relays (like the popular Zubr or similar devices). However, there’s an often overlooked yet crucial protector of our electrical appliances that we rarely see or think about: the varistor.
What is a Varistor?
A varistor is a component found in the power supply units of almost every electrical device in your home, except perhaps for simple appliances like boilers and kettles. Recently, the use of Surge Protective Devices (SPDs) has become popular, incorporating varistors to safeguard both solar panel systems and AC networks.
Why are Varistors and SPDs So Effective?
1. Lightning-Fast Response Time
Varistors operate incredibly quickly, reacting within 20-25 nanoseconds. This speed is thousands of times faster than traditional voltage relays, making them highly effective in preventing damage from sudden surges.
2. How Varistors Work
Normal Operation: Under normal voltage conditions, a varistor has an extremely high resistance, acting almost like air and allowing current to pass without interference.
Surge Conditions: When voltage exceeds a certain threshold (set by the manufacturer and indicated on the varistor), its resistance drops sharply. At this point, the varistor begins to conduct and protect your equipment.
3. Functions of a Varistor
Absorbing Impulse Surges: Varistors can absorb short-term voltage spikes, converting the excess energy into heat. This ability is useful for mitigating transient surges caused by the starting of large motors or industrial equipment.
Protecting Against Sustained Surges: In the case of prolonged or extremely powerful surges, the varistor can burn out, causing a short circuit that trips the circuit breaker. This action helps save your equipment by taking the brunt of the destructive energy.
Do You Need a Varistor or SPD for AC Systems?
1. Standard Use: Voltage Relays
For most households, voltage relays provide adequate protection. Most of your equipment already has built-in varistor-based protection.
2. When Additional Protection is Necessary
Sensitive Equipment: If you own sensitive equipment like MRI machines, high-end audio systems, military, or scientific apparatus, additional protection is necessary. This could be SPDs, varistors, or specialized filters using varistors, capacitors, and inductors.
Nearby Sources of Disturbance: If you have identified sources of interference or surge problems in your vicinity, extra protection is recommended.
In these cases, you might need SPDs, additional varistors, or specialized network filters.
Key Takeaway
There’s no such thing as too much money, too many batteries, too many solar panels, or too large a varistor. Always opt for the larger size—20 mm varistors offer robust protection and are crucial for safeguarding your equipment.
Conclusion
While often overlooked, varistors play a vital role in protecting your electrical appliances from surges. Understanding their function and knowing when additional protection is needed can help you maintain a safe and reliable electrical system in your home. Investing in the right protective measures, such as SPDs and larger varistors, can prevent costly damages and ensure the longevity of your equipment.
By recognizing the importance of varistors and implementing appropriate protection strategies, you can enhance the resilience of your home’s electrical systems and keep your valuable appliances safe from unexpected surges.
