Aumov LV Ultramov Varistor Design Guide Page 17 Varistor Design Guide For DC & Automotive Applications

DC Application Varistor Design Guide 2015 Littelfuse DC Application Varistor Design Guide MOV General Applications Metal Oxide Varistors (MOVs) are commonly used to suppress transients in many applications, such as Surge Protection Devices (SPD), Uninterruptible Power Supplies (UPSs), AC Power Taps, AC Power Meters or other products. Lightning, inductive load switching, or capacitor bank switching are often the sources of these overvoltage transients. Under normal operating conditions, the AC line voltage applied to an MOV is not expected to exceed the MOV's Maximum AC RMS Voltage Rating or Maximum Continuous Operating Voltage (MCOV). Occasionally, overvoltage transients that exceed these limits may occur. These transients are clamped to a suitable voltage level by the MOV, provided that the transient energy does not exceed the MOV's maximum rating. Transient Suppression Techniques (continued) Technology Key Features and Protection Characteristics Surge Energy Rating Range Typical Voltage Clamping Speeds Typical Capacitance/ Insertion Loss Mounting Size/ Packaging Options Multi-Layer Varistors (MLVs) Compact and capable of handling significant surges for their size Low thru Medium Moderate High Miniature Surface Mount Metal-Oxide Varistors (MOVs) Capable of withstanding very high energy transients; wide range of options Medium thru Very High Moderate High Radial Leaded, Industrial Terminal Gas Discharge Tubes (GDTs) Switches that turn to on state and shunt overvoltage to ground using a contained inert gas as an insulator Medium thru High Fast Low Surface Mount, Axial Leaded, 2/3 Lead Radial Pulse-Guard ESD Suppressors Extremely low capacitance; fast response time; compact size Low Moderate Low Miniature Surface Mount PLED LED Protectors Shunt function bypasses open LEDs; ESD and reverse power protection Low Very Fast Medium Miniature Surface Mount TVS Diode Array SPA Diodes Low capacitance / low clamping voltage; compact size Low thru Medium Very Fast Low Extensive range of surface mount options TVS Diodes Fast response to fast transients; wide range of options Medium thru High Fast High Axial Leaded, Radial Leaded, Surface Mount SIDACtor Protection Thyristors Specifically designed to serve stringent telecom/ networking standards Medium thru High Very Fast Low Extensive range of surface mount and thru-hole options 16

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