Table of Contents

Power Controllers Reference Data Glossary
Celsius to Fahrenheit / Fahrenheit to Celsius. . . . . . . . . . . . 127Ratings of Listed Heater VoltagesOperated on Other Voltages. . . . . . . 129Conversion Factors. . . . . . . . . . . . . . 130Commonly Used Geometric Areas and Volume. . . . . . . . . . . . . . . 133Physical Properties of Solids, Liquids and Gases. . . . . . . . . . . . . . 134Properties of Non-Metallic Solids. . . . . . . . . . . . . . . . . . . . . . 134Properties of Metals. . . . . . . . . . 137Properties of Metals in Liquid State. . . . . . . . . . . . . . . . . 139Properties of Liquids. . . . . . . . . . 140Properties of Gases. . . . . . . . . . 143Properties of Air. . . . . . . . . . . . . 143Corrosion Guide. . . . . . . . . . . . . . . . 144Examples of Applications. . . . . . . . . 156Cabinet Freeze Protection. . . . . 156Heating a Steel Mold. . . . . . . . . . 158Melting of Aluminum. . . . . . . . . . 164Heating Liquid in a Tank. . . . . . . 174Heating a Flowing Liquid. . . . . . 178Air Duct Heater. . . . . . . . . . . . . . 182Drying a Moving Web of Cloth. . 186 Watlow Products andTechnical SupportDeliveredWorldwide
Product Overview. . . . . . . . . . . . . . .101Five Basic Types. . . . . . . . . . . . . . . . 102Theory of SCR Power Controllers. . 108Methods of Firing SCRs. . . . . . . . . . 109Enclosure Guidelines. . . . . . . . . . . . 112Heater Life and Selection of PowerHandling Device. . . . . . . . . . . . . . . . 113SCR Protective devices. . . . . . . . . . 114 Definitions of Commonly Used Terms Used in Heating, Sensing and Controlling. . . . . . . . . . . . . . . . . 188 Watlow’s worldwide sales and distributor network If you don’t find what you need in thisApplication Guide, call the Watlowoffice nearest you listed on thefollowing One phone call gives you instant access to experttechnical advice, applicationassistance and after-the-sale service.In addition, more than 150 authorized distributors are located in the U.S. and 42 other countries.For up-to-date information onWatlow’s new products or services,see Watlow’s home page on theInternet at http://www.watlow.com. Wiring Practices
Electrical Noise. . . . . . . . . ... . . . . . 116Helpful Wiring Guidelines. . . . . . . . . 118Input Power Wiring. . . . . . . . . . . . . . 120Output Wiring. . . . . . . . . . . . . . . . . . 122SCR Wiring – Tips and SpecialConsiderations. . . . . . . . . . . . . . . . . 124 2