16-07-2013, 02:19 PM
POLY FUSE
POLY FUSE[.docx (Size: 38.07 KB / Downloads: 24)
INTRODUCTION
Current flow in a conductor always generates heat. Excess heat is damaging to electrical components. Over current protection devices are used to protect conductors from excessive current flow. Thus protective devices are designed to keep the flow of current in a circuit at a safe level to prevent the circuit conductors from overheating. A fuse is a one-time over-current protection device employing a fusible link that melts (blows) after the current exceeds a certain level for a certain length of time. Typically, a wire or chemical compound breaks the circuit when the current exceeds the rated value. A fuse interrupts excessive current so that further damage by overheating or fire is prevented. Wiring regulations often define a maximum fuse current rating for particular circuits. Over current protection devices are essential in electrical systems to limit threats to human life and property damage. Fuses are selected to allow passage of normal current and of excessive current only for short periods.