Metal Oxide Varistors (MOVs)are rated for specific AC line operating voltages, and exceeding these limits through the application of a sustained abnormal over-voltage condition could result in overheating and damage to the MOV. The Littelfuse TMOV25S™ (Thermal MOV) Series was designed to address this condition in a single integrated package. The Littelfuse TMOV25S™ Series incorporates a patented integrated thermally responsive element within the body of the device which will open-circuit the varistor in case of overheating due to abnormal over-voltage events. The TMOV25S™ Series is based on the Littelfuse UltraMOV™ 25S Series which meets the surge suppressor component recognition requirements of UL 1449 3rd edition for both cord connected and permanently connected TVSS end products. UL1449 3rd Edition approval of TMOV25S Series is currently pending related to the integrated thermal element of this series and product release is anticipated for summer or 2011. Please contact your Littelfuse product representative to discuss alternatives and for additional information.