Fused Varistors Ease Transition to UL1449 3rd Edition

By adding a thermal fuse within the industry-standard 34mm outline, Littelfuse TMOV34S varistors save board re-design to satisfy the latest UL1449 specification.

UL1449 3rd edition requires any over-current protection to be included in the surge path. This may require designers to move an existing fuse, but the TMOV34S with integrated fuse element delivers a faster and easier solution. The two-pin devices are direct replacements for standard 34mm varistors, and also save component and assembly costs compared to existing circuits featuring a separate fuse.

In addition to the direct-replacement devices, the TMOV34S family also includes three-pin versions that provide an extra pin to indicate when the element has opened. This can be connected to neutral via an LED and series-resistor network to produce a visual indication when the element has opened and the circuit is no longer protected by the MOV.

The family includes devices rated for voltages from 115 to 750V AC root mean square, delivering fast and reliable disconnect performance with surge-current protection up to 40kA.

 

FEATURES Outline and pad layout shared with standard 34mm MOV Meets ANSI/IEEE C 62.11 accelerated-ageing test requirements Recognised by UL under file no. E75901

APPLICATIONS Uninterruptible Power Supplies (UPS) AC power supplies Transient-Voltage Surge-Suppression (TVSS) modules AC-panel protection modules Electrical service panels Cellular base stations

 

 

Littelfuse / TMOV34S