INTERNAL FAULT INDICATOR FOR POWER ELECTRICAL DEVICES

摘要

An internal fault indicator for an electrical device is triggered by a suddenincrease in pressure as occurs when an insulation failure creates an electricarc. The heat released in the arc is transferred onto the surrounding volumecausing localized overheating, vaporization and decomposition of theinsulating material. The resulting pressure surge moves a diaphragm. Themovement of the diaphragm releases a spring driven plunger from a barrel whichextends through the housing of the electrical device. Prior to activation theplunger is held in an "armed" position by a retaining pin. Upon triggering,the plunger is pushed by the spring until it protrudes from the housing toprovide a visual signal of the internal fault. A pressure relief valve may beintegrated with the internal fault indicator.