This part is a kind of semiconductor called TNR12G221K.
Function of this product has G Series / Metal Oxide Varistors.
Manufacturers : United Chemi-Con
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Some of the text within the PDF file :
G Series Ⅲ Metal Oxide Varistor Ⅲ General Purpose Ⅲ UL 1414 and 1449 Approved Ⅲ CSA 097864 Approved Ⅲ 85؇C Maximum Temperature Actual Size The G series is the standard metal oxide varistor series from UCC/NCC. These MOVs are available in a wide variety of voltages and sizes, which will make them ideal in most applications where a surge protector is needed. The G series is also ideal because of the variety of UL and CSA approvals. The varistors with a 5mm or 7.5mm lead spacing are available with ammo pack taping. Refer to the Mini -Glossary at the end of the metal oxide varistors section for additional technical information and specifications. Summary of Specifications Ⅲ Radial lead terminals. Ⅲ Operating temperature range: 40؇C to 85؇C. Ⅲ Maxi [ ... ]