What are the differences between gas discharge tubes (GDTs) and metal oxide varistors (MOVs)?

Power Circuit Protection
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Gas discharge tubes (GDTs) and metal oxide varistors (MOVs) are both commonly used circuit protection technologies. You might be wondering what the working differences are between them. How do these products work, and which is right for you?

littelfuse GDT part number SL1021A090R
littelfuse GDT part number SL1021A090R640×640 44.4 KB

Littelfuse MOV part number V300LA40AP
Littelfuse MOV part number V300LA40AP640×640 61.5 KB

In short: gas discharge tubes adopt the Crowbar technology (switching, with a low voltage after conduction), while varistors use the Clamping technology, with a high voltage after conduction.

Gas Discharge Tube Arresters (GDT)

Working principle: This is a voltage-driven component. The GDT remains in open circuit condition until the voltage in the circuit reaches a specific level. When the voltage reaches this level, the gas in the GDT ionizes and conducts electricity, thus grounding the high-voltage state. After the high voltage drops, the gas de-ionizes, and the GDT returns to the open circuit state until the next surge. Compared with other circuit protection components, GDTs can absorb a large amount of transient increased energy.

Varistors, MOVs

Working principle: The MOV is based on the Clamping technology. It is a non-linear resistive component, and its resistance value changes with the voltage across its two ends. Under normal operating voltage, the MOV exhibits a high-resistance state. When the voltage rises to a certain extent (referred to as the varistor voltage), the resistance value of the MOV drops sharply, and it starts to conduct, thereby limiting the overvoltage in the system within a certain range.

More Littelfuse circuit protection products

Littelfuse Circuit Protection products provide stable and reliable signal transmission guarantee for all kinds of precision electronic devices by virtue of their precise adjustment relationship with capacitance, dynamic resistance, etc. in terms of high-frequency characteristics, and their performance is excellent in the industry.

More Q&A on Littelfuse Circuit Protection Products Technology:

I. Questions Related to Component Characteristics

  1. What are the classifications of gas discharge tubes?

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  3. In Littelfuse circuit protection products, what kind of current is I in I²t?

  4. What are the differences between discharge tubes and metal oxide varistors?

II. Questions Related to Selection

  1. How to select metal oxide varistors for overvoltage protection?

  2. Do Littelfuse overcurrent protection fuses/circuit breakers have self-resetting function?

  3. The difference in the selection of overvoltage / overcurrent between AC and DC input terminals?

  4. When to Use PTC Resettable Fuses and Metal Fuses?

  5. What parameters differ between surface mount and through hole fuse selections?

  6. Under what general circumstances can AC components be directly used in DC circuits?

  7. Can the method of paralleling small-capacity fuses be used to achieve the purpose of fast fusing?

III. Questions Related to Applications

  1. What design requirements for overcurrent and overvoltage protection?

  2. In which fields are gas discharge tubes mainly applied? Do they have directionality?

  3. Are overcurrent and overvoltage protection for AC/DC power inputs used in charging piles?

  4. Can Littelfuse Circuit Protection Products Protect Against Overvoltage and Overcurrent?

  5. How to understand the fuse explosion-proof test?

  6. How to specifically know the time of time-delay fusing fuses?