30 Series
Axial Terminal / Surface Mount / Heat Sinkable Packaging
Wirewound Resistors employ special winding techniques to maximize the effective joule rating of each resistor. Most wirewound resistors are wound with the objective of meeting the stated power (wattage) rating and keeping cost low through the use of automatic winding equipment. Typically, manufacturers will allow substitution of resistance wire, depending on material availability. On tight tolerance wirewounds some type of abrasive adjustment to the resistance wire is often used to maximize production yields. Both of these procedures can adversely affect the joule rating and fusing current of a wirewound resistor, and this is often the reason that the manufacturer does not publish a fixed joule rating. Since no wire substitutions are allowed, and no abrasive adjusting is permitted in this family, Ohmite can publish a fixed joule rating and fusing current for each part number in the series. In order to provide the broadest selection of packaging, Ohmite has developed standard offerings in three different package types-axial, SMD, and heat sinkable.
