Why Use IT Earthing System?
Introduction The standard IEC 60364 have used the following nomenclature to specify types of earthing: First letter – Relationship of the power system to earth: T = direct connection of …
Calculating Flash Protection Boundary Distances
In NFPA 70E, the short-circuit symmetrical ampacity from a bolted 3-phase fault at the transformer terminals is calculated with the following formula: where Isc = Amperes, V = Volts, %Z …
Arc-Flash Hazards
An arc-flash is a release of energy caused by a flow of fault current through an electrical arc plasma. Arc flashes can occur when racking a breaker in/out, removing a …
Safety Against Overvoltages
Overvoltages are unwanted potentials occurring in electrical systems between a phase conductor and the earth or ground, or between phase conductors having a peak value greater than the peak of …
Arc Flash Incident – 13.8 kV Indoor Switchgear Part II
Accumulation of moisture inside the 13.8 kV main bus and insulation tracking caused another arc-flash incident on the 13.8 kV Indoor Switchgear. An annual preventive maintenance was scheduled prior to …
Arc Flash Incident – 13.8 kV Indoor Switchgear
An indoor 13.8kV Vacuum Circuit Breaker switchgear has an arc flash incident this week. Investigation results showed that the wet weather increased the humidity inside the switchroom, incomplete covering of …