Machine Design

Bridge Cable Fails, TPE to the Rescue

After large rubberinsulated cables for a lift bridge connecting Minnesota and Wisconsin failed after less than two years, Northwire Inc., Osceola,Wis., replaced them with 40% smallerdiameter cables insulated with Hytrel thermoplastic elastomer (TPE) from DuPont, Wilmington, Del.

“TPE’s high dielectric strength and toughness let Northwire spec thinner cables that have longer flex life at a given bend radius,” says Northwire Director of Sales Ted Beach. The old cable used ethylene- propylene rubber for insulating its 50 conductors (16 awg) and measured 1.86 in. (47 mm) in diameter. The replacement cable is just 1.1 in. (28 mm) in diameter and its conductors are each insulated with 0.01 in. (0.25 mm) of Hytrel.

Make contact
, (800) 441-0575,
Northwire Inc.,
(800) 468-1516,

The thinner cable insulated with DuPont Hytrel (left) has a longer flex life than its ethylene-propylene rubber-insulated counterpart (right) whcih failed after less than two years of service on a lift bridge.

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