Varistors are common electronic components that play a crucial role in circuits. They are capable of limiting overvoltage and protecting other components in the circuit from damage.
In practical applications, varistors can sometimes break down due to various reasons. So, how can you tell if a varistor has been damaged or broken down?
1. Causes of Varistor Breakdown
Varistors can break down due to factors such as overvoltage, excessive load, long-term aging, or manufacturing defects. When a varistor breaks down, its resistance value drops sharply, leakage current increases, and the appearance may crack or deform. Its overvoltage protection performance is significantly reduced, indicating that the varistor is damaged.
How to Determine If a Varistor Has Been Damaged
If you notice abnormal behavior in a circuit and suspect the varistor may be damaged, conduct a preliminary inspection immediately.
1. Visual Inspection
Check the varistor for any obvious signs of damage, such as burning, cracking, or deformation. These are usually clear indications that the varistor has suffered a severe overvoltage surge or overheating.
2. Measure the Resistance
Use a multimeter or similar tool to measure the varistor’s resistance. Under normal conditions (without overvoltage triggering), a varistor should have a high resistance value.
If the measured resistance is very low or close to zero, it is likely that the varistor has broken down.
3. Check Circuit Connections
In addition to inspecting the varistor itself, check its connections with other circuit components.
Loose connections or poor contact can also cause circuit issues, but these do not necessarily mean the varistor is damaged.
What to Do If a Varistor Is Damaged
If you confirm that the varistor has been damaged, take the following steps:
Replace the varistor promptly with the same model to ensure the circuit continues functioning properly.
Review the component selection and circuit layout. If the varistor’s rating is inappropriate or the layout is poorly designed, make necessary corrections.
Consider environmental factors, as these can also lead to varistor breakdown. Take proper environmental protection measures.
Perform regular circuit maintenance and monitoring. This is an important preventative measure to avoid varistor failure.
This article is provided by JYH HSU (JEC) Electronics. JEC is a research, development, production, and sales-oriented company specializing in manufacturing and selling various electronic components such as capacitors and resistors.
Post time: May-27-2025