Retract Coil Burn-Out

摘要

Workers at a private contractor that makes torpedoes for the U.S. Navy were having a problem with an assembly line directional valve coil that would burn out often, causing production issues. The valve, a D05, three-position, spring-centered, 115-volt AC explosion-proof design, continually lost the retract side "air gap" solenoid coil. The assembly line took six months to install and debug. Once it was turned over to production, this problem started showing up. The OEM sent a new valve, thinking there must be a problem with the original unit. It didn't help. The contractors' electrical engineer suggested they interchange the "A" and "B" ports to the cylinder and do the same with the two coils. The problem still persisted. Whichever coil controlled the retract function would eventually fail. The pump delivered 20 gpm, and the valve was rated for 26 gpm.