TFMOV is a combination of varistors (MOV) and thermal protection component. Since varistor has the characteristics of aging or degrading; TFMOV can separate the varistor from the main circuitry by opening the thermal protection component when the varistor (MOV) degrades or fails. It is often used in which requires high reliability and weather withstanding, such as photovoltaic inverters, communication equipment, and power supplies in data centers, etc.
Nominal Varistor Voltage
Voltage, at specified d.c. current used as a reference point in the component characteristic ----IEC 61051-1
8/20 Current Impulse
Current impulse with a nominal virtual front time of 8 µs and a nominal time to half-value of 20 µs. ---- IEC 61643-11
1.2/50 Voltage Impulse
Voltage impulse with a nominal virtual front time of 1.2 µs and a nominal time to half-value of 50 µs. ---- IEC 61643-11
Maximum Continuous Operating Voltage
Maximum r.m.s. voltage, which may be continuously applied to the SPD's mode of protection. ---- IEC 61643-11
Nominal Discharge Current
Crest value of the current through the SPD having a current waveshape of 8/20. ---- IEC 61643-11
Impulse Discharge Current for Class I Test
Crest value of a discharge current through the SPD with specified charge transfer Q and specified energy W/R in the specified time.
---- IEC 61643-11
Peak voltage developed across the varistor terminations under standard atmospheric conditions, when passing an 8/20 class current pulse. ----IEC 61051-1
Maximum Discharge Current
Crest value of a current through the SPD having an 8/20 waveshape and magnitude according to the manufacturers specification. Imax is equal to or greater than In. ---- IEC 61643-11
Capacitance across the MOV measured at a specified frequency and voltage. ----IEC 61643-331
Voltage Protection Level
Maximum voltage to be expected at the SPD terminals due to an impulse stress with defined voltage steepness and an impulse stress with a discharge current with given amplitude and waveshape. ---- IEC 61643-11
Short Circuit Current Rating
The suitability of an SPD for use on an AC power circuit that is capable of delivering not more than a declared rms symmetrical current at a declared voltage during a short circuit condition. ----UL 1449
A non-resettable device incorporating a THERMAL ELEMENT which will open a circuit once only when exposed for a sufficient length of time to a temperature in excess of that for which it has been designed. ----IEC 60691
Alloy Type Thermal-Link, Alloy is the thermal element.
● Telecom Equipment
● String Inverter in Photovoltaic System
● AC / DC Power Supply
● Uninterruptable Power Supply (UPS)
● Surge Protective Device (SPD)
● Electric Meter
● Power Distribution Unit (PDU)
View Product Structure, Principle, Application Video
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Select critical raw materials: Must be from a manufacturer with quality management system (ISO9001, IATF16949) certification.
2. The voltage applied continuously to the TFMOV can not exceed its maximum continuous operating voltage Uc.
3. When atmosphere press is from 80 kPa to 106 kPa, the related altitude shall be from 2000 meters to - 500 meters.
4. Do not touch the product body or pins directly when power is on, to avoid electric shock.
5. Do not clean the TFMOV with strong polar solvent such as ketone, esters, benzene, halogenated hydrocarbon, to avoid damaging the enclosure.
6. It should have a reliable grounding when using these products.
TFMOV is a non-repairable product. For safety sake, please use equivalent TFMOV for replacement.
Do not store TFMOV at high temperature, high humidity or corrosive gas environment. To avoid reducing the solderability of the pins, please use them up within 1 year after receiving the goods.
Do not install the TFMOV on a place that may often suffer severe continuous vibration.
Do not take violent action such as knocking when assembling to avoid mechanical damage.
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Thermal Fuse & MOV (TFMOV) Catalog
According to the working principle and failure mode of varistor, this paper will explain the disadvantage of only overcurrent protection against MOV’s failure. At the same time, the best protection mode –Thermal protection is promoted.