Troubleshooting Fuse Problems
Contents
1. Troubleshooting Fuse Problems mi WATLOW Nuisance fuse blowing can be hard to find although sometimes opening or x raying the blown fuse may lead to the answer Caution Wear Safety glasses when opening and inspecting fuses P ae ws ce g a Ps my Watlow Winona 1 LCr 03 08 05 1241 Bundy Blvd Winona MN 55987 Telephone 507 494 5656 2004 Watlow Electric Manufacturing Company Troubleshooting Fuse Problems mz WATLOW Semiconductor fuses are made with thin silver layers that have several areas necked down to allow opening in case of a severe overload These strips are packed in silica sand that will melt and form glass to quench the arc as the link blows open Watlow Winona 2 LCr 03 08 05 1241 Bundy Blvd Winona MN 55987 Telephone 507 494 5656 2004 Watlow Electric Manufacturing Company Troubleshooting Fuse Problems w WATLOW When examining the fuse look for the following 1 If only the center links are open the fuse probably failed from fatigue Either the fuse was too hot or was operated at a partial overload for a long time Check ambient temperature and fuse sizing 2 If only the links at one end are open the fuse probably failed due to a loose connection at that end and the fuse holder terminal got too hot Check for loose connections at fuse ends 3 If all links are blown there was a short circuit Things to look for if all links blew e One open f2. use is almost always a short to ground e Two open fuses is a short from phase to phase Intermittent opening of all links usually is a short to ground which does not weld the short in place Semiconductor fuses open fast enough that the short can go away after the heater cools To locate the defective heater requires a destructive test Using a hi pot tester may find the short but if voltage arcs across the insulator it will leave a carbon trail and the heater is no longer usable By removing the power control semiconductor fuses and running the heaters directly with slow blow fuses the element will weld itself to the sheath when the heater shorts and then can be located with an ohm meter once the heater cools Watlow Winona 3 LCr 03 08 05 1241 Bundy Blvd Winona MN 55987 Telephone 507 494 5656 2004 Watlow Electric Manufacturing Company
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