FCMOV Product Introduction
Current Challenges in Overvoltage Protection
Metal oxide varistors (MOVs) have long been a common, cost-effective solution for overvoltage circuit protection and are well suited to transient surge protection. However, prolonged or repeated overvoltage can cause excessive current and thermal runaway. Alternative thermal protection solutions on the market can be bulky and expensive.
MOVs may also be exposed to sustained abnormal mains voltages rather than brief transients. Under sustained abnormal overvoltage or overcurrent conditions, such as those addressed by UL 1449, a varistor may enter thermal runaway, resulting in overheating, smoke, and possibly fire. Beyond the risk to life, such failures may lead to substantial compensation claims and litigation. Products complying with UL 1449 safety requirements must provide protection against this failure mode.
MOVs may also be exposed to sustained abnormal mains voltages rather than brief transients. Under sustained abnormal overvoltage or overcurrent conditions, such as those addressed by UL 1449, a varistor may enter thermal runaway, resulting in overheating, smoke, and possibly fire. Beyond the risk to life, such failures may lead to substantial compensation claims and litigation. Products complying with UL 1449 safety requirements must provide protection against this failure mode.
Temporary Overvoltage Characteristics– This refers to the ability of a varistor to withstand power-frequency overvoltage. Whether an MOV can withstand such overvoltage in a low-voltage system affects electrical system safety, making temporary overvoltage characteristics an important safety consideration. If the varistor cannot withstand power-frequency overvoltage, short-circuit and breakdown failures can occur, causing overheating and ignition around the MOV and potentially a fire.