What is a TMOV?
TMOV® Varistors in SPD and AC Line Applications. Introduction. Metal Oxide Varistors (MOVs) are commonly used to suppress transients in many applications such as: Surge Protection Devices (SPD), Uninterruptible Power Supplies (UPS), AC Power Taps, AC Power Meters or other products.
Do varistors go bad?
After prolonged use they can degrade and the material that makes up the disc can start a leakage current due to internal damage after a surge event, this will create a higher leakage current over time and before you know it we have a thermal runaway event.
How do you test a zinc oxide varistor?
Turn the multimeter on and set its function knob to read resistance. Touch the meter probe tips to the MOV’s leads and measure its resistance. If it has a resistance much under 100 ohms, it has blown.
How does thermofuse varistors protect power circuit?
ThermoFuse™ varistors are housed components, which consist of a disk varistor in series with a thermally coupled fuse. If the varistor overheats, the thermal fuse activates and disconnects it from the power circuit, thus preventing the occurrence of fires. This increases reliability and protects the equipment.
Why are the tmov and itomv varistors thermally protected?
The TMOV and iTOMV varistors offer quick thermal response due to the close proximity of the integrated thermal element to the MOV body. The integrated configuration also offers lower inductance than most discrete solutions resulting in improved clamping performance to fast over-voltage transients.
What are the features of a varistor switch?
They are thermally-protected and built with high-quality, dependable materials. Features manually-operated, foot-operated, and mechanically-operated switches; and switches operated by temperature or pressure. Reliable standard and thermal protected varistor, available in a variety of forms, surge current capability up to 70,000 Amp.