Power Electronics

Varistor Recognized to UL1449 up to 750VAC Continuous Operating Voltage

Littelfuse, Inc. announced the addition of the TMOV34S® varistor series to its Thermally-Protected MOV (TMOV®) line of products with UL1449 recognition to the demanding higher range voltage values from 115VAC to 750VAC. TMOV34S Series devices are the industry's only varistors that carry UL1449 recognition to 750VAC to protect circuits from abnormal overvoltage conditions. TMOV34S varistor series' higher voltage range makes it an ideal solution for solar power inverter and high voltage power supply applications.

Due to the close proximity of their integrated thermal element to the MOV body, they can offer quick thermal response in a far smaller component, an important advantage over competitive solutions that rely on mechanical designs. The TMOV34S Series joins the TMOV25S varistor series already available from Littelfuse, which is finding wide acceptance in outdoor LED lighting applications.

Unlike other products on the market that employ mechanical means of thermal protection that add bulk, the TMOV25S Series varistor line has integrated thermal protection, allowing for a smaller package size that is more compatible with luminaire designs. The temperature-protected 25mm varistor disc not only ensures the TMOV25S Series passes the new DOE Surge Immunity standards for Outdoor LED Lighting, but provides integrated thermal protection to guard against end-of-life MOV failures and temporary overvoltage faults.

The TMOV25S Series includes an optional third leg, designed to allow the varistor to indicate that it has activated its self-protection function, thereby notifying the luminaire system that protection is no longer available, so the front end TMOV25 series varistor or the luminaire now requires replacement.

Devices in the TMOV34S varistor series combine a 34mm-square-format varistor element (MOV) with high surge capability (up to 40kA) with an integrated thermally activated element. This element will open in the event of overheating due to abnormal overvoltage, limited current conditions. TMOV34S Series devices can offer quick thermal response to overvoltages in high energy circuits 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 response to fast overvoltage transients. Some TMOV34S devices include a monitor lead, which may be connected to signaling circuitry to indicate if the MOV has been disconnected from the circuit.

Littelfuse Inc.
Part Number: TMOV34S

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